Question

I am using Sqlite database and storing empty values for rows.I am using this code for storing empty values in the database:

            ContentValues values = new ContentValues();
            values.put(KEY_NAME,"");
            values.put(KEY_PH_NO,"");           
            values.put(KEY_FOLDER_NAME, contact.getFolderName());
            values.put(KEY_FolderAddress, contact.getParentFolderAddress());
            values.put(KEY_TIME, contact.getTime());    
            values.put(KEY_DATE, contact.getDate());

And i am using following query to retrieve the database entry having empty values:

String selectQuery = "SELECT  * FROM " + TABLE_CONTACTS + " WHERE "+KEY_FolderAddress+" ='"
                     +FileAddress+"'"+" AND "+KEY_FOLDER_NAME+" ='"+FileName+"'"+" AND "+KEY_DATE+" ='"+"0"+"'"
                     +" AND "+KEY_PH_NO+" ='"+""+"'"+" AND "+KEY_NAME+" ='"+""+"'";

But i am getting this exception while retrieving empty values:

12-25 11:52:40.531: E/Exception:(1990): android.database.sqlite.SQLiteException: unknown error: , while compiling: SELECT  * FROM rules WHERE folderaddress ='/sdcard/Velosys/a' AND folder_name ='a' AND date ='0' AND phone_number ='' AND name ='' Exception occured in getTimeOfTheFolderFromContact() of DatabaseHandlerRule.java

I have searched a lot but did not get the solution.Please help me in finding the right way to retrieve empty values from sqlite database.Thanks in advance

Edit:

I am storing 2 entries with empty values i.e KEY_NAME and KEY_PH_NO

This is the table format:

String CREATE_CONTACTS_TABLE = "CREATE TABLE " + TABLE_CONTACTS + "("
            + KEY_ID + " INTEGER PRIMARY KEY, " +KEY_NAME+" TEXT, "+ KEY_PH_NO + " TEXT, "
            +KEY_FOLDER_NAME+" TEXT, "+ KEY_FolderAddress + " TEXT, "+KEY_TIME + " TEXT, "+KEY_DATE+" TEXT "+")";
            db.execSQL(CREATE_CONTACTS_TABLE);

Answer 1

You must use some common value to store in database:

ContentValues values = new ContentValues();
            values.put(KEY_NAME,"null");
            values.put(KEY_PH_NO,"null");  

Please use this code to retrieve null values:
Yes you are right because the “null” value will be stored as a string value in database.

int i = resultSet.getInt(resultSet.getColumnIndex(columnName));
        String str = resultSet.getString(resultSet.getColumnIndex(columnName));
        boolean bool = resultSet.isNull(resultSet.getColumnIndex(columnName));
        if( str == null )
        {
            return -1;
        }
        return i;