core/java/android/database/sqlite/SQLiteQueryBuilder.java - platform/frameworks/base - Gitiles

 /*
  * Copyright (C) 2006 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package android.database.sqlite;

 import android.database.Cursor;
 import android.database.DatabaseUtils;
 import android.database.sqlite.SQLiteDatabase;
 import android.provider.BaseColumns;
 import android.text.TextUtils;
 import android.util.Config;
 import android.util.Log;

 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
 import java.util.Map.Entry;

 /**
  * This is a convience class that helps build SQL queries to be sent to
  * {@link SQLiteDatabase} objects.
  */
 public class SQLiteQueryBuilder
 {
     private static final String TAG = "SQLiteQueryBuilder";

     private Map<String, String> mProjectionMap = null;
     private String mTables = "";
     private StringBuilder mWhereClause = new StringBuilder(64);
     private boolean mDistinct;
     private SQLiteDatabase.CursorFactory mFactory;

     public SQLiteQueryBuilder() {
         mDistinct = false;
         mFactory = null;
     }

     /**
      * Mark the query as DISTINCT.
      *
      * @param distinct if true the query is DISTINCT, otherwise it isn't
      */
     public void setDistinct(boolean distinct) {
         mDistinct = distinct;
     }

     /**
      * Returns the list of tables being queried
      *
      * @return the list of tables being queried
      */
     public String getTables() {
         return mTables;
     }

     /**
      * Sets the list of tables to query. Multiple tables can be specified to perform a join.
      * For example:
      *   setTables("foo, bar")
      *   setTables("foo LEFT OUTER JOIN bar ON (foo.id = bar.foo_id)")
      *
      * @param inTables the list of tables to query on
      */
     public void setTables(String inTables) {
         mTables = inTables;
     }

     /**
      * Append a chunk to the WHERE clause of the query. All chunks appended are surrounded
      * by parenthesis and ANDed with the selection passed to {@link #query}. The final
      * WHERE clause looks like:
      *
      * WHERE (&lt;append chunk 1>&lt;append chunk2>) AND (&lt;query() selection parameter>)
      *
      * @param inWhere the chunk of text to append to the WHERE clause.
      */
     public void appendWhere(CharSequence inWhere) {
         if (mWhereClause.length() == 0) {
             mWhereClause.append('(');
         }
         mWhereClause.append(inWhere);
     }

     /**
      * Append a chunk to the WHERE clause of the query. All chunks appended are surrounded
      * by parenthesis and ANDed with the selection passed to {@link #query}. The final
      * WHERE clause looks like:
      *
      * WHERE (&lt;append chunk 1>&lt;append chunk2>) AND (&lt;query() selection parameter>)
      *
      * @param inWhere the chunk of text to append to the WHERE clause. it will be escaped
      * to avoid SQL injection attacks
      */
     public void appendWhereEscapeString(String inWhere) {
         if (mWhereClause.length() == 0) {
             mWhereClause.append('(');
         }
         DatabaseUtils.appendEscapedSQLString(mWhereClause, inWhere);
     }

     /**
      * Sets the projection map for the query.  The projection map maps
      * from column names that the caller passes into query to database
      * column names. This is useful for renaming columns as well as
      * disambiguating column names when doing joins. For example you
      * could map "name" to "people.name".  If a projection map is set
      * it must contain all column names the user may request, even if
      * the key and value are the same.
      *
      * @param columnMap maps from the user column names to the database column names
      */
     public void setProjectionMap(Map<String, String> columnMap) {
         mProjectionMap = columnMap;
     }

     /**
      * Sets the cursor factory to be used for the query.  You can use
      * one factory for all queries on a database but it is normally
      * easier to specify the factory when doing this query.  @param
      * factory the factor to use
      */
     public void setCursorFactory(SQLiteDatabase.CursorFactory factory) {
         mFactory = factory;
     }

     /**
      * Build an SQL query string from the given clauses.
      *
      * @param distinct true if you want each row to be unique, false otherwise.
      * @param tables The table names to compile the query against.
      * @param columns A list of which columns to return. Passing null will
      *            return all columns, which is discouraged to prevent reading
      *            data from storage that isn't going to be used.
      * @param where A filter declaring which rows to return, formatted as an SQL
      *            WHERE clause (excluding the WHERE itself). Passing null will
      *            return all rows for the given URL.
      * @param groupBy A filter declaring how to group rows, formatted as an SQL
      *            GROUP BY clause (excluding the GROUP BY itself). Passing null
      *            will cause the rows to not be grouped.
      * @param having A filter declare which row groups to include in the cursor,
      *            if row grouping is being used, formatted as an SQL HAVING
      *            clause (excluding the HAVING itself). Passing null will cause
      *            all row groups to be included, and is required when row
      *            grouping is not being used.
      * @param orderBy How to order the rows, formatted as an SQL ORDER BY clause
      *            (excluding the ORDER BY itself). Passing null will use the
      *            default sort order, which may be unordered.
      * @param limit Limits the number of rows returned by the query,
      *            formatted as LIMIT clause. Passing null denotes no LIMIT clause.
      * @return the SQL query string
      */
     public static String buildQueryString(
             boolean distinct, String tables, String[] columns, String where,
             String groupBy, String having, String orderBy, String limit) {
         if (TextUtils.isEmpty(groupBy) && !TextUtils.isEmpty(having)) {
             throw new IllegalArgumentException(
                     "HAVING clauses are only permitted when using a groupBy clause");
         }

         StringBuilder query = new StringBuilder(120);

         query.append("SELECT ");
         if (distinct) {
             query.append("DISTINCT ");
         }
         if (columns != null && columns.length != 0) {
             appendColumns(query, columns);
         } else {
             query.append("* ");
         }
         query.append("FROM ");
         query.append(tables);
         appendClause(query, " WHERE ", where);
         appendClause(query, " GROUP BY ", groupBy);
         appendClause(query, " HAVING ", having);
         appendClause(query, " ORDER BY ", orderBy);
         appendClauseEscapeClause(query, " LIMIT ", limit);

         return query.toString();
     }

     private static void appendClause(StringBuilder s, String name, String clause) {
         if (!TextUtils.isEmpty(clause)) {
             s.append(name);
             s.append(clause);
         }
     }

     private static void appendClauseEscapeClause(StringBuilder s, String name, String clause) {
         if (!TextUtils.isEmpty(clause)) {
             s.append(name);
             DatabaseUtils.appendEscapedSQLString(s, clause);
         }
     }

     /**
      * Add the names that are non-null in columns to s, separating
      * them with commas.
      */
     public static void appendColumns(StringBuilder s, String[] columns) {
         int n = columns.length;

         for (int i = 0; i < n; i++) {
             String column = columns[i];

             if (column != null) {
                 if (i > 0) {
                     s.append(", ");
                 }
                 s.append(column);
             }
         }
         s.append(' ');
     }

     /**
      * Perform a query by combining all current settings and the
      * information passed into this method.
      *
      * @param db the database to query on
      * @param projectionIn A list of which columns to return. Passing
      *   null will return all columns, which is discouraged to prevent
      *   reading data from storage that isn't going to be used.
      * @param selection A filter declaring which rows to return,
      *   formatted as an SQL WHERE clause (excluding the WHERE
      *   itself). Passing null will return all rows for the given URL.
      * @param selectionArgs You may include ?s in selection, which
      *   will be replaced by the values from selectionArgs, in order
      *   that they appear in the selection. The values will be bound
      *   as Strings.
      * @param groupBy A filter declaring how to group rows, formatted
      *   as an SQL GROUP BY clause (excluding the GROUP BY
      *   itself). Passing null will cause the rows to not be grouped.
      * @param having A filter declare which row groups to include in
      *   the cursor, if row grouping is being used, formatted as an
      *   SQL HAVING clause (excluding the HAVING itself).  Passing
      *   null will cause all row groups to be included, and is
      *   required when row grouping is not being used.
      * @param sortOrder How to order the rows, formatted as an SQL
      *   ORDER BY clause (excluding the ORDER BY itself). Passing null
      *   will use the default sort order, which may be unordered.
      * @return a cursor over the result set
      * @see android.content.ContentResolver#query(android.net.Uri, String[],
      *      String, String[], String)
      */
     public Cursor query(SQLiteDatabase db, String[] projectionIn,
             String selection, String[] selectionArgs, String groupBy,
             String having, String sortOrder) {
         return query(db, projectionIn, selection, selectionArgs, groupBy, having, sortOrder,
                 null /* limit */);
     }

     /**
      * Perform a query by combining all current settings and the
      * information passed into this method.
      *
      * @param db the database to query on
      * @param projectionIn A list of which columns to return. Passing
      *   null will return all columns, which is discouraged to prevent
      *   reading data from storage that isn't going to be used.
      * @param selection A filter declaring which rows to return,
      *   formatted as an SQL WHERE clause (excluding the WHERE
      *   itself). Passing null will return all rows for the given URL.
      * @param selectionArgs You may include ?s in selection, which
      *   will be replaced by the values from selectionArgs, in order
      *   that they appear in the selection. The values will be bound
      *   as Strings.
      * @param groupBy A filter declaring how to group rows, formatted
      *   as an SQL GROUP BY clause (excluding the GROUP BY
      *   itself). Passing null will cause the rows to not be grouped.
      * @param having A filter declare which row groups to include in
      *   the cursor, if row grouping is being used, formatted as an
      *   SQL HAVING clause (excluding the HAVING itself).  Passing
      *   null will cause all row groups to be included, and is
      *   required when row grouping is not being used.
      * @param sortOrder How to order the rows, formatted as an SQL
      *   ORDER BY clause (excluding the ORDER BY itself). Passing null
      *   will use the default sort order, which may be unordered.
      * @param limit Limits the number of rows returned by the query,
      *   formatted as LIMIT clause. Passing null denotes no LIMIT clause.
      * @return a cursor over the result set
      * @see android.content.ContentResolver#query(android.net.Uri, String[],
      *      String, String[], String)
      */
     public Cursor query(SQLiteDatabase db, String[] projectionIn,
             String selection, String[] selectionArgs, String groupBy,
             String having, String sortOrder, String limit) {
         if (mTables == null) {
             return null;
         }

         String sql = buildQuery(
                 projectionIn, selection, selectionArgs, groupBy, having,
                 sortOrder, limit);

         if (Log.isLoggable(TAG, Log.DEBUG)) {
             Log.d(TAG, "Performing query: " + sql);
         }
         return db.rawQueryWithFactory(
                 mFactory, sql, selectionArgs,
                 SQLiteDatabase.findEditTable(mTables));
     }

     /**
      * Construct a SELECT statement suitable for use in a group of
      * SELECT statements that will be joined through UNION operators
      * in buildUnionQuery.
      *
      * @param projectionIn A list of which columns to return. Passing
      *    null will return all columns, which is discouraged to
      *    prevent reading data from storage that isn't going to be
      *    used.
      * @param selection A filter declaring which rows to return,
      *   formatted as an SQL WHERE clause (excluding the WHERE
      *   itself).  Passing null will return all rows for the given
      *   URL.
      * @param selectionArgs You may include ?s in selection, which
      *   will be replaced by the values from selectionArgs, in order
      *   that they appear in the selection.  The values will be bound
      *   as Strings.
      * @param groupBy A filter declaring how to group rows, formatted
      *   as an SQL GROUP BY clause (excluding the GROUP BY itself).
      *   Passing null will cause the rows to not be grouped.
      * @param having A filter declare which row groups to include in
      *   the cursor, if row grouping is being used, formatted as an
      *   SQL HAVING clause (excluding the HAVING itself).  Passing
      *   null will cause all row groups to be included, and is
      *   required when row grouping is not being used.
      * @param sortOrder How to order the rows, formatted as an SQL
      *   ORDER BY clause (excluding the ORDER BY itself). Passing null
      *   will use the default sort order, which may be unordered.
      * @param limit Limits the number of rows returned by the query,
      *   formatted as LIMIT clause. Passing null denotes no LIMIT clause.
      * @return the resulting SQL SELECT statement
      */
     public String buildQuery(
             String[] projectionIn, String selection, String[] selectionArgs,
             String groupBy, String having, String sortOrder, String limit) {
         String[] projection = computeProjection(projectionIn);

         if (mWhereClause.length() > 0) {
             mWhereClause.append(')');
         }

         // Tack on the user's selection, if present.
         if (selection != null && selection.length() > 0) {
             if (mWhereClause.length() > 0) {
                 mWhereClause.append(" AND ");
             }

             mWhereClause.append('(');
             mWhereClause.append(selection);
             mWhereClause.append(')');
         }

         return buildQueryString(
                 mDistinct, mTables, projection, mWhereClause.toString(),
                 groupBy, having, sortOrder, limit);
     }

     /**
      * Construct a SELECT statement suitable for use in a group of
      * SELECT statements that will be joined through UNION operators
      * in buildUnionQuery.
      *
      * @param typeDiscriminatorColumn the name of the result column
      *   whose cells will contain the name of the table from which
      *   each row was drawn.
      * @param unionColumns the names of the columns to appear in the
      *   result.  This may include columns that do not appear in the
      *   table this SELECT is querying (i.e. mTables), but that do
      *   appear in one of the other tables in the UNION query that we
      *   are constructing.
      * @param columnsPresentInTable a Set of the names of the columns
      *   that appear in this table (i.e. in the table whose name is
      *   mTables).  Since columns in unionColumns include columns that
      *   appear only in other tables, we use this array to distinguish
      *   which ones actually are present.  Other columns will have
      *   NULL values for results from this subquery.
      * @param computedColumnsOffset all columns in unionColumns before
      *   this index are included under the assumption that they're
      *   computed and therefore won't appear in columnsPresentInTable,
      *   e.g. "date * 1000 as normalized_date"
      * @param typeDiscriminatorValue the value used for the
      *   type-discriminator column in this subquery
      * @param selection A filter declaring which rows to return,
      *   formatted as an SQL WHERE clause (excluding the WHERE
      *   itself).  Passing null will return all rows for the given
      *   URL.
      * @param selectionArgs You may include ?s in selection, which
      *   will be replaced by the values from selectionArgs, in order
      *   that they appear in the selection.  The values will be bound
      *   as Strings.
      * @param groupBy A filter declaring how to group rows, formatted
      *   as an SQL GROUP BY clause (excluding the GROUP BY itself).
      *   Passing null will cause the rows to not be grouped.
      * @param having A filter declare which row groups to include in
      *   the cursor, if row grouping is being used, formatted as an
      *   SQL HAVING clause (excluding the HAVING itself).  Passing
      *   null will cause all row groups to be included, and is
      *   required when row grouping is not being used.
      * @return the resulting SQL SELECT statement
      */
     public String buildUnionSubQuery(
             String typeDiscriminatorColumn,
             String[] unionColumns,
             Set<String> columnsPresentInTable,
             int computedColumnsOffset,
             String typeDiscriminatorValue,
             String selection,
             String[] selectionArgs,
             String groupBy,
             String having) {
         int unionColumnsCount = unionColumns.length;
         String[] projectionIn = new String[unionColumnsCount];

         for (int i = 0; i < unionColumnsCount; i++) {
             String unionColumn = unionColumns[i];

             if (unionColumn.equals(typeDiscriminatorColumn)) {
                 projectionIn[i] = "'" + typeDiscriminatorValue + "' AS "
                         + typeDiscriminatorColumn;
             } else if (i <= computedColumnsOffset
                        || columnsPresentInTable.contains(unionColumn)) {
                 projectionIn[i] = unionColumn;
             } else {
                 projectionIn[i] = "NULL AS " + unionColumn;
             }
         }
         return buildQuery(
                 projectionIn, selection, selectionArgs, groupBy, having,
                 null /* sortOrder */,
                 null /* limit */);
     }

     /**
      * Given a set of subqueries, all of which are SELECT statements,
      * construct a query that returns the union of what those
      * subqueries return.
      * @param subQueries an array of SQL SELECT statements, all of
      *   which must have the same columns as the same positions in
      *   their results
      * @param sortOrder How to order the rows, formatted as an SQL
      *   ORDER BY clause (excluding the ORDER BY itself).  Passing
      *   null will use the default sort order, which may be unordered.
      * @param limit The limit clause, which applies to the entire union result set
      *
      * @return the resulting SQL SELECT statement
      */
     public String buildUnionQuery(String[] subQueries, String sortOrder, String limit) {
         StringBuilder query = new StringBuilder(128);
         int subQueryCount = subQueries.length;
         String unionOperator = mDistinct ? " UNION " : " UNION ALL ";

         for (int i = 0; i < subQueryCount; i++) {
             if (i > 0) {
                 query.append(unionOperator);
             }
             query.append(subQueries[i]);
         }
         appendClause(query, " ORDER BY ", sortOrder);
         appendClause(query, " LIMIT ", limit);
         return query.toString();
     }

     private String[] computeProjection(String[] projectionIn) {
         if (projectionIn != null && projectionIn.length > 0) {
             if (mProjectionMap != null) {
                 String[] projection = new String[projectionIn.length];
                 int length = projectionIn.length;

                 for (int i = 0; i < length; i++) {
                     String userColumn = projectionIn[i];
                     String column = mProjectionMap.get(userColumn);

                     if (column == null) {
                         throw new IllegalArgumentException(
                                     "Invalid column " + projectionIn[i]);
                     } else {
                         projection[i] = column;
                     }
                 }
                 return projection;
             } else {
                 return projectionIn;
             }
         } else if (mProjectionMap != null) {
             // Return all columns in projection map.
             Set<Entry<String, String>> entrySet = mProjectionMap.entrySet();
             String[] projection = new String[entrySet.size()];
             Iterator<Entry<String, String>> entryIter = entrySet.iterator();
             int i = 0;

             while (entryIter.hasNext()) {
                 Entry<String, String> entry = entryIter.next();

                 // Don't include the _count column when people ask for no projection.
                 if (entry.getKey().equals(BaseColumns._COUNT)) {
                     continue;
                 }
                 projection[i++] = entry.getValue();
             }
             return projection;
         }
         return null;
     }
 }
	/*
	* Copyright (C) 2006 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package android.database.sqlite;

	import android.database.Cursor;
	import android.database.DatabaseUtils;
	import android.database.sqlite.SQLiteDatabase;
	import android.provider.BaseColumns;
	import android.text.TextUtils;
	import android.util.Config;
	import android.util.Log;

	import java.util.Iterator;
	import java.util.Map;
	import java.util.Set;
	import java.util.Map.Entry;

	/**
	* This is a convience class that helps build SQL queries to be sent to
	* {@link SQLiteDatabase} objects.
	*/
	public class SQLiteQueryBuilder
	{
	private static final String TAG = "SQLiteQueryBuilder";

	private Map<String, String> mProjectionMap = null;
	private String mTables = "";
	private StringBuilder mWhereClause = new StringBuilder(64);
	private boolean mDistinct;
	private SQLiteDatabase.CursorFactory mFactory;

	public SQLiteQueryBuilder() {
	mDistinct = false;
	mFactory = null;
	}

	/**
	* Mark the query as DISTINCT.
	*
	* @param distinct if true the query is DISTINCT, otherwise it isn't
	*/
	public void setDistinct(boolean distinct) {
	mDistinct = distinct;
	}

	/**
	* Returns the list of tables being queried
	*
	* @return the list of tables being queried
	*/
	public String getTables() {
	return mTables;
	}

	/**
	* Sets the list of tables to query. Multiple tables can be specified to perform a join.
	* For example:
	* setTables("foo, bar")
	* setTables("foo LEFT OUTER JOIN bar ON (foo.id = bar.foo_id)")
	*
	* @param inTables the list of tables to query on
	*/
	public void setTables(String inTables) {
	mTables = inTables;
	}

	/**
	* Append a chunk to the WHERE clause of the query. All chunks appended are surrounded
	* by parenthesis and ANDed with the selection passed to {@link #query}. The final
	* WHERE clause looks like:
	*
	* WHERE (<append chunk 1><append chunk2>) AND (<query() selection parameter>)
	*
	* @param inWhere the chunk of text to append to the WHERE clause.
	*/
	public void appendWhere(CharSequence inWhere) {
	if (mWhereClause.length() == 0) {
	mWhereClause.append('(');
	}
	mWhereClause.append(inWhere);
	}

	/**
	* Append a chunk to the WHERE clause of the query. All chunks appended are surrounded
	* by parenthesis and ANDed with the selection passed to {@link #query}. The final
	* WHERE clause looks like:
	*
	* WHERE (<append chunk 1><append chunk2>) AND (<query() selection parameter>)
	*
	* @param inWhere the chunk of text to append to the WHERE clause. it will be escaped
	* to avoid SQL injection attacks
	*/
	public void appendWhereEscapeString(String inWhere) {
	if (mWhereClause.length() == 0) {
	mWhereClause.append('(');
	}
	DatabaseUtils.appendEscapedSQLString(mWhereClause, inWhere);
	}

	/**
	* Sets the projection map for the query. The projection map maps
	* from column names that the caller passes into query to database
	* column names. This is useful for renaming columns as well as
	* disambiguating column names when doing joins. For example you
	* could map "name" to "people.name". If a projection map is set
	* it must contain all column names the user may request, even if
	* the key and value are the same.
	*
	* @param columnMap maps from the user column names to the database column names
	*/
	public void setProjectionMap(Map<String, String> columnMap) {
	mProjectionMap = columnMap;
	}

	/**
	* Sets the cursor factory to be used for the query. You can use
	* one factory for all queries on a database but it is normally
	* easier to specify the factory when doing this query. @param
	* factory the factor to use
	*/
	public void setCursorFactory(SQLiteDatabase.CursorFactory factory) {
	mFactory = factory;
	}

	/**
	* Build an SQL query string from the given clauses.
	*
	* @param distinct true if you want each row to be unique, false otherwise.
	* @param tables The table names to compile the query against.
	* @param columns A list of which columns to return. Passing null will
	* return all columns, which is discouraged to prevent reading
	* data from storage that isn't going to be used.
	* @param where A filter declaring which rows to return, formatted as an SQL
	* WHERE clause (excluding the WHERE itself). Passing null will
	* return all rows for the given URL.
	* @param groupBy A filter declaring how to group rows, formatted as an SQL
	* GROUP BY clause (excluding the GROUP BY itself). Passing null
	* will cause the rows to not be grouped.
	* @param having A filter declare which row groups to include in the cursor,
	* if row grouping is being used, formatted as an SQL HAVING
	* clause (excluding the HAVING itself). Passing null will cause
	* all row groups to be included, and is required when row
	* grouping is not being used.
	* @param orderBy How to order the rows, formatted as an SQL ORDER BY clause
	* (excluding the ORDER BY itself). Passing null will use the
	* default sort order, which may be unordered.
	* @param limit Limits the number of rows returned by the query,
	* formatted as LIMIT clause. Passing null denotes no LIMIT clause.
	* @return the SQL query string
	*/
	public static String buildQueryString(
	boolean distinct, String tables, String[] columns, String where,
	String groupBy, String having, String orderBy, String limit) {
	if (TextUtils.isEmpty(groupBy) && !TextUtils.isEmpty(having)) {
	throw new IllegalArgumentException(
	"HAVING clauses are only permitted when using a groupBy clause");
	}

	StringBuilder query = new StringBuilder(120);

	query.append("SELECT ");
	if (distinct) {
	query.append("DISTINCT ");
	}
	if (columns != null && columns.length != 0) {
	appendColumns(query, columns);
	} else {
	query.append("* ");
	}
	query.append("FROM ");
	query.append(tables);
	appendClause(query, " WHERE ", where);
	appendClause(query, " GROUP BY ", groupBy);
	appendClause(query, " HAVING ", having);
	appendClause(query, " ORDER BY ", orderBy);
	appendClauseEscapeClause(query, " LIMIT ", limit);

	return query.toString();
	}

	private static void appendClause(StringBuilder s, String name, String clause) {
	if (!TextUtils.isEmpty(clause)) {
	s.append(name);
	s.append(clause);
	}
	}

	private static void appendClauseEscapeClause(StringBuilder s, String name, String clause) {
	if (!TextUtils.isEmpty(clause)) {
	s.append(name);
	DatabaseUtils.appendEscapedSQLString(s, clause);
	}
	}

	/**
	* Add the names that are non-null in columns to s, separating
	* them with commas.
	*/
	public static void appendColumns(StringBuilder s, String[] columns) {
	int n = columns.length;

	for (int i = 0; i < n; i++) {
	String column = columns[i];

	if (column != null) {
	if (i > 0) {
	s.append(", ");
	}
	s.append(column);
	}
	}
	s.append(' ');
	}

	/**
	* Perform a query by combining all current settings and the
	* information passed into this method.
	*
	* @param db the database to query on
	* @param projectionIn A list of which columns to return. Passing
	* null will return all columns, which is discouraged to prevent
	* reading data from storage that isn't going to be used.
	* @param selection A filter declaring which rows to return,
	* formatted as an SQL WHERE clause (excluding the WHERE
	* itself). Passing null will return all rows for the given URL.
	* @param selectionArgs You may include ?s in selection, which
	* will be replaced by the values from selectionArgs, in order
	* that they appear in the selection. The values will be bound
	* as Strings.
	* @param groupBy A filter declaring how to group rows, formatted
	* as an SQL GROUP BY clause (excluding the GROUP BY
	* itself). Passing null will cause the rows to not be grouped.
	* @param having A filter declare which row groups to include in
	* the cursor, if row grouping is being used, formatted as an
	* SQL HAVING clause (excluding the HAVING itself). Passing
	* null will cause all row groups to be included, and is
	* required when row grouping is not being used.
	* @param sortOrder How to order the rows, formatted as an SQL
	* ORDER BY clause (excluding the ORDER BY itself). Passing null
	* will use the default sort order, which may be unordered.
	* @return a cursor over the result set
	* @see android.content.ContentResolver#query(android.net.Uri, String[],
	* String, String[], String)
	*/
	public Cursor query(SQLiteDatabase db, String[] projectionIn,
	String selection, String[] selectionArgs, String groupBy,
	String having, String sortOrder) {
	return query(db, projectionIn, selection, selectionArgs, groupBy, having, sortOrder,
	null /* limit */);
	}

	/**
	* Perform a query by combining all current settings and the
	* information passed into this method.
	*
	* @param db the database to query on
	* @param projectionIn A list of which columns to return. Passing
	* null will return all columns, which is discouraged to prevent
	* reading data from storage that isn't going to be used.
	* @param selection A filter declaring which rows to return,
	* formatted as an SQL WHERE clause (excluding the WHERE
	* itself). Passing null will return all rows for the given URL.
	* @param selectionArgs You may include ?s in selection, which
	* will be replaced by the values from selectionArgs, in order
	* that they appear in the selection. The values will be bound
	* as Strings.
	* @param groupBy A filter declaring how to group rows, formatted
	* as an SQL GROUP BY clause (excluding the GROUP BY
	* itself). Passing null will cause the rows to not be grouped.
	* @param having A filter declare which row groups to include in
	* the cursor, if row grouping is being used, formatted as an
	* SQL HAVING clause (excluding the HAVING itself). Passing
	* null will cause all row groups to be included, and is
	* required when row grouping is not being used.
	* @param sortOrder How to order the rows, formatted as an SQL
	* ORDER BY clause (excluding the ORDER BY itself). Passing null
	* will use the default sort order, which may be unordered.
	* @param limit Limits the number of rows returned by the query,
	* formatted as LIMIT clause. Passing null denotes no LIMIT clause.
	* @return a cursor over the result set
	* @see android.content.ContentResolver#query(android.net.Uri, String[],
	* String, String[], String)
	*/
	public Cursor query(SQLiteDatabase db, String[] projectionIn,
	String selection, String[] selectionArgs, String groupBy,
	String having, String sortOrder, String limit) {
	if (mTables == null) {
	return null;
	}

	String sql = buildQuery(
	projectionIn, selection, selectionArgs, groupBy, having,
	sortOrder, limit);

	if (Log.isLoggable(TAG, Log.DEBUG)) {
	Log.d(TAG, "Performing query: " + sql);
	}
	return db.rawQueryWithFactory(
	mFactory, sql, selectionArgs,
	SQLiteDatabase.findEditTable(mTables));
	}

	/**
	* Construct a SELECT statement suitable for use in a group of
	* SELECT statements that will be joined through UNION operators
	* in buildUnionQuery.
	*
	* @param projectionIn A list of which columns to return. Passing
	* null will return all columns, which is discouraged to
	* prevent reading data from storage that isn't going to be
	* used.
	* @param selection A filter declaring which rows to return,
	* formatted as an SQL WHERE clause (excluding the WHERE
	* itself). Passing null will return all rows for the given
	* URL.
	* @param selectionArgs You may include ?s in selection, which
	* will be replaced by the values from selectionArgs, in order
	* that they appear in the selection. The values will be bound
	* as Strings.
	* @param groupBy A filter declaring how to group rows, formatted
	* as an SQL GROUP BY clause (excluding the GROUP BY itself).
	* Passing null will cause the rows to not be grouped.
	* @param having A filter declare which row groups to include in
	* the cursor, if row grouping is being used, formatted as an
	* SQL HAVING clause (excluding the HAVING itself). Passing
	* null will cause all row groups to be included, and is
	* required when row grouping is not being used.
	* @param sortOrder How to order the rows, formatted as an SQL
	* ORDER BY clause (excluding the ORDER BY itself). Passing null
	* will use the default sort order, which may be unordered.
	* @param limit Limits the number of rows returned by the query,
	* formatted as LIMIT clause. Passing null denotes no LIMIT clause.
	* @return the resulting SQL SELECT statement
	*/
	public String buildQuery(
	String[] projectionIn, String selection, String[] selectionArgs,
	String groupBy, String having, String sortOrder, String limit) {
	String[] projection = computeProjection(projectionIn);

	if (mWhereClause.length() > 0) {
	mWhereClause.append(')');
	}

	// Tack on the user's selection, if present.
	if (selection != null && selection.length() > 0) {
	if (mWhereClause.length() > 0) {
	mWhereClause.append(" AND ");
	}

	mWhereClause.append('(');
	mWhereClause.append(selection);
	mWhereClause.append(')');
	}

	return buildQueryString(
	mDistinct, mTables, projection, mWhereClause.toString(),
	groupBy, having, sortOrder, limit);
	}

	/**
	* Construct a SELECT statement suitable for use in a group of
	* SELECT statements that will be joined through UNION operators
	* in buildUnionQuery.
	*
	* @param typeDiscriminatorColumn the name of the result column
	* whose cells will contain the name of the table from which
	* each row was drawn.
	* @param unionColumns the names of the columns to appear in the
	* result. This may include columns that do not appear in the
	* table this SELECT is querying (i.e. mTables), but that do
	* appear in one of the other tables in the UNION query that we
	* are constructing.
	* @param columnsPresentInTable a Set of the names of the columns
	* that appear in this table (i.e. in the table whose name is
	* mTables). Since columns in unionColumns include columns that
	* appear only in other tables, we use this array to distinguish
	* which ones actually are present. Other columns will have
	* NULL values for results from this subquery.
	* @param computedColumnsOffset all columns in unionColumns before
	* this index are included under the assumption that they're
	* computed and therefore won't appear in columnsPresentInTable,
	* e.g. "date * 1000 as normalized_date"
	* @param typeDiscriminatorValue the value used for the
	* type-discriminator column in this subquery
	* @param selection A filter declaring which rows to return,
	* formatted as an SQL WHERE clause (excluding the WHERE
	* itself). Passing null will return all rows for the given
	* URL.
	* @param selectionArgs You may include ?s in selection, which
	* will be replaced by the values from selectionArgs, in order
	* that they appear in the selection. The values will be bound
	* as Strings.
	* @param groupBy A filter declaring how to group rows, formatted
	* as an SQL GROUP BY clause (excluding the GROUP BY itself).
	* Passing null will cause the rows to not be grouped.
	* @param having A filter declare which row groups to include in
	* the cursor, if row grouping is being used, formatted as an
	* SQL HAVING clause (excluding the HAVING itself). Passing
	* null will cause all row groups to be included, and is
	* required when row grouping is not being used.
	* @return the resulting SQL SELECT statement
	*/
	public String buildUnionSubQuery(
	String typeDiscriminatorColumn,
	String[] unionColumns,
	Set<String> columnsPresentInTable,
	int computedColumnsOffset,
	String typeDiscriminatorValue,
	String selection,
	String[] selectionArgs,
	String groupBy,
	String having) {
	int unionColumnsCount = unionColumns.length;
	String[] projectionIn = new String[unionColumnsCount];

	for (int i = 0; i < unionColumnsCount; i++) {
	String unionColumn = unionColumns[i];

	if (unionColumn.equals(typeDiscriminatorColumn)) {
	projectionIn[i] = "'" + typeDiscriminatorValue + "' AS "
	+ typeDiscriminatorColumn;
	} else if (i <= computedColumnsOffset
	\|\| columnsPresentInTable.contains(unionColumn)) {
	projectionIn[i] = unionColumn;
	} else {
	projectionIn[i] = "NULL AS " + unionColumn;
	}
	}
	return buildQuery(
	projectionIn, selection, selectionArgs, groupBy, having,
	null /* sortOrder */,
	null /* limit */);
	}

	/**
	* Given a set of subqueries, all of which are SELECT statements,
	* construct a query that returns the union of what those
	* subqueries return.
	* @param subQueries an array of SQL SELECT statements, all of
	* which must have the same columns as the same positions in
	* their results
	* @param sortOrder How to order the rows, formatted as an SQL
	* ORDER BY clause (excluding the ORDER BY itself). Passing
	* null will use the default sort order, which may be unordered.
	* @param limit The limit clause, which applies to the entire union result set
	*
	* @return the resulting SQL SELECT statement
	*/
	public String buildUnionQuery(String[] subQueries, String sortOrder, String limit) {
	StringBuilder query = new StringBuilder(128);
	int subQueryCount = subQueries.length;
	String unionOperator = mDistinct ? " UNION " : " UNION ALL ";

	for (int i = 0; i < subQueryCount; i++) {
	if (i > 0) {
	query.append(unionOperator);
	}
	query.append(subQueries[i]);
	}
	appendClause(query, " ORDER BY ", sortOrder);
	appendClause(query, " LIMIT ", limit);
	return query.toString();
	}

	private String[] computeProjection(String[] projectionIn) {
	if (projectionIn != null && projectionIn.length > 0) {
	if (mProjectionMap != null) {
	String[] projection = new String[projectionIn.length];
	int length = projectionIn.length;

	for (int i = 0; i < length; i++) {
	String userColumn = projectionIn[i];
	String column = mProjectionMap.get(userColumn);

	if (column == null) {
	throw new IllegalArgumentException(
	"Invalid column " + projectionIn[i]);
	} else {
	projection[i] = column;
	}
	}
	return projection;
	} else {
	return projectionIn;
	}
	} else if (mProjectionMap != null) {
	// Return all columns in projection map.
	Set<Entry<String, String>> entrySet = mProjectionMap.entrySet();
	String[] projection = new String[entrySet.size()];
	Iterator<Entry<String, String>> entryIter = entrySet.iterator();
	int i = 0;

	while (entryIter.hasNext()) {
	Entry<String, String> entry = entryIter.next();

	// Don't include the _count column when people ask for no projection.
	if (entry.getKey().equals(BaseColumns._COUNT)) {
	continue;
	}
	projection[i++] = entry.getValue();
	}
	return projection;
	}
	return null;
	}
	}