Android数据库查询语句

/**
* Query the given table, returning a {@link Cursor} over the result set.
*
* @param table The table name 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 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 table.
* @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 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.
* @return A {@link Cursor} object, which is positioned before the first entry. Note that
* {@link Cursor}s are not synchronized, see the documentation for more details.
* @see Cursor
*/
public Cursor query(String table, String[] columns, String selection,
String[] selectionArgs, String groupBy, String having,
String orderBy) {

return query(false, table, columns, selection, selectionArgs, groupBy,
having, orderBy, null /* limit */);
}