Query the database table to check whether a table is empty or not - Android Database

Android examples for Database:SQL Query

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Description

Query the database table to check whether a table is empty or not

Demo Code

/*//  w  w w  .j  a  va  2  s  . c  om
 * 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;

public class Main {
    /**
     * Query the table to check whether a table is empty or not
     * @param db the database the table is in
     * @param table the name of the table to query
     * @return True if the table is empty
     * @hide
     */
    public static boolean queryIsEmpty(SQLiteDatabase db, String table) {
        long isEmpty = longForQuery(db, "select exists(select 1 from "
                + table + ")", null);
        return isEmpty == 0;
    }

    /**
     * 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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