Query the table for the number of rows in the database table. - Android Database

Android examples for Database:SQL Query

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Description

Query the table for the number of rows in the database table.

Demo Code

/*//from   w  w  w  .ja v a2  s.  c o  m
 * 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 com.book2s;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteStatement;

import android.text.TextUtils;

public class Main {
    /**
     * Query the table for the number of rows in the table.
     * @param db the database the table is in
     * @param table the name of the table to query
     * @return the number of rows in the table
     */
    public static long queryNumEntries(SQLiteDatabase db, String table) {
        return queryNumEntries(db, table, null, null);
    }

    /**
     * Query the table for the number of rows in the table.
     * @param db the database the table is in
     * @param table the name of the table to query
     * @param selection A filter declaring which rows to return,
     *              formatted as an SQL WHERE clause (excluding the WHERE itself).
     *              Passing null will count all rows for the given table
     * @return the number of rows in the table filtered by the selection
     */
    public static long queryNumEntries(SQLiteDatabase db, String table,
            String selection) {
        return queryNumEntries(db, table, selection, null);
    }

    /**
     * Query the table for the number of rows in the table.
     * @param db the database the table is in
     * @param table the name of the table to query
     * @param selection A filter declaring which rows to return,
     *              formatted as an SQL WHERE clause (excluding the WHERE itself).
     *              Passing null will count 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.
     * @return the number of rows in the table filtered by the selection
     */
    public static long queryNumEntries(SQLiteDatabase db, String table,
            String selection, String[] selectionArgs) {
        String s = (!TextUtils.isEmpty(selection)) ? " where " + selection
                : "";
        return longForQuery(db, "select count(*) from " + table + s,
                selectionArgs);
    }

    /**
     * Utility method to run the query on the db and return the value in the
     * first column of the first row.
     */
    public static long longForQuery(SQLiteDatabase db, String query,
            String[] selectionArgs) {
        SQLiteStatement prog = db.compileStatement(query);
        try {
            return longForQuery(prog, selectionArgs);
        } finally {
            prog.close();
        }
    }

    /**
     * Utility method to run the pre-compiled query and return the value in the
     * first column of the first row.
     */
    public static long longForQuery(SQLiteStatement prog,
            String[] selectionArgs) {
        prog.bindAllArgsAsStrings(selectionArgs);
        return prog.simpleQueryForLong();
    }
}

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