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Commit ac4daee2 authored by Hyoseong Kim's avatar Hyoseong Kim Committed by git-lg-database.lge.com
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Add additional Method that check whether a table is empty or not 

Application Devleopers are using queryNumEntries API
implemented by "COUNT(*)" to check whether a table is empty or not.
COUNT(*)  has to process the entire table to compute the result.
But, "EXISTS" can stop after a single matching row has been found.
So, Using "EXISTS" is more faster than "COUNT(*)"
I added new API using "EXISTS" to check whether a table is empty or not

Change-Id: Idcc2633d0a5349c59f41e125cf34c9dc6622cdbe
parent f5276c16

core/java/android/database/DatabaseUtils.java

+12 −0
Original line number Diff line number Diff line
@@ -791,6 +791,18 @@ public class DatabaseUtils { 
                    selectionArgs);

    }



    /**

     * 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.