Android SQLite update columns only if NULL or empty

Question

In android I am trying to update a table in SQLite database, but I want to achieve, that it will update only empty columns or columns with NULL value.

public void fillCal(String swin, String swout, String ripout, String kateg) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues contentValues = new ContentValues();

    contentValues.put(COL_10, swin);
    contentValues.put(COL_11, swout);
    contentValues.put(COL_12, ripout);

    db.update(TABLE_NAME, contentValues,COL_7 + " = '" + kateg + "'", null);db.close();
}

So if COL_10 is empty or has a NULL value, then I need to update it with a new value. Otherwise if there is already a value in COL_10, do nothing with that column. The same for COL11 and COL12.

I thought to add another conditions in this line, like:

db.update(TABLE_NAME, contentValues,COL_7 + " = '" + kateg + "' AND COL10!='' AND COL11!='' AND COL12!=''", null);db.close();

or even I wanted first to get the values from other query:

 String Query2 = "SELECT * FROM "+ TABLE_NAME ";

        Cursor cursor2 = db.rawQuery(Query2, null);
        while (cursor2.moveToNext()) {
        output_col10 = cursor2.getString(cursor2.getColumnIndexOrThrow(COL_10));

and then check if output_col10 is null or length>0, but this is an overkill I think.

Is there a possibility to do it simplier in my db.update function?

According to last answer I updated it :

public void fillCal(String swin, String swout, String ripout, String kateg) {

        SQLiteDatabase db = this.getWritableDatabase();
        String Query = "UPDATE " + TABLE_NAME + " SET " + COL_10 + " = CASE WHEN " + COL_10 + " IS NULL OR " + COL_10 + " = '' THEN '" + swin + "' ELSE " + COL_10 + " END" + " where " + COL_7 + " = '" + kateg + "'";
        Cursor cursor = db.rawQuery(Query, null);
        cursor.close();
   
        String Query1 = "UPDATE " + TABLE_NAME + " SET " + COL_11 + " = CASE WHEN " + COL_11 + " IS NULL OR " + COL_11 + " = '' THEN '" + swout + "' ELSE " + COL_11 + " END" + " where " + COL_7 + " = '" + kateg + "'";
        Cursor cursor1 = db.rawQuery(Query1, null);
        cursor1.close();

        String Query2 = "UPDATE " + TABLE_NAME + " SET " + COL_12 + " = CASE WHEN " + COL_12 + " IS NULL OR " + COL_12 + " = '' THEN '" + ripout + "' ELSE " + COL_12 + " END" + " where " + COL_7 + " = '" + kateg + "'";
        Cursor cursor2 = db.rawQuery(Query2, null);

        cursor2.close();
        db.close();
    }

but for some reason the columns are still empty and not updated with any value.

Answer 1

You can update all the columns with a single UPDATE statement and execSQL():

String query = "UPDATE " + TABLE_NAME + " SET " + 
               COL_10 + " = CASE WHEN " + COL_10 + " IS NULL OR " + COL_10 + " = '' THEN '" + swout + "' ELSE " + COL_10 + " END," + 
               COL_11 + " = CASE WHEN " + COL_11 + " IS NULL OR " + COL_11 + " = '' THEN '" + swout + "' ELSE " + COL_11 + " END," + 
               COL_12 + " = CASE WHEN " + COL_12 + " IS NULL OR " + COL_12 + " = '' THEN '" + swout + "' ELSE " + COL_12 + " END "  + 
               "WHERE " + COL_7 + " = '" + kateg + "'";
db.execSQL(query);