When to use ExecuteScalar, ExecuteReader, and ExecuteNonQuery? [closed]

Answer 1

Use ExecuteScalar when your query returns a single value. If it returns more results, then the end result is the first column of the first row. An example might be SELECT Count(*) from MyTable

Use ExecuteReader for getting result set with multiple rows/columns (e.g., SELECT col1, col2 from MyTable.

Use ExecuteNonQuery for SQL statements which will not retrieve results from database but make updation in existing database (e.g., UPDATE, INSERT, etc.).