Android SQLiteDatabase: Reading one column

I have a one row database just for saving app data. My goal is to read one column (one value) from it.

This query returns all the columns in a Cursor:

public Cursor readAll() {
       return getReadableDatabase().query(tableName, null, null, null, null, null, null);
    }

It returns a Cursor with one row in it, just perfect. However, I don't want to read all columns at once, because it's slow as I have blob's in db too. Instead, I'd like to read just one column at a time, separately. For example, for a column called "TEXT" it would be this:

public Cursor readText() {
      String[] projection = new String[]{"TEXT"};
      return getReadableDatabase().query(tableName,开发者_如何学Go projection, null, null, null, null, null);
    }

However, this won't work, as I get back a Cursor with zero rows.

So, how to read a specific column from SQLiteBatabase in Android?

public Cursor readText() {
      return getReadableDatabase().rawQuery("SELECT colName FROM myTable", new String[] {});
    }

Syntax seems to be correct. Check please that you use right name of the column. Showing the table generation code and actual query code could help.

You can use this one also

public Cursor readText() {
  return getReadableDatabase().rawQuery("SELECT column_name FROM table_name", null);
}