When to use ExecuteScalar, ExecuteReader, and ExecuteNonQuery?
c#, vb.net
Solution
- `ExecuteScalar()` only returns the value from the first column of the first row of your query.
- `ExecuteReader()` returns an object that can iterate over the entire result set while only keeping one record in memory at a time.
- `ExecuteNonQuery()` does not return data at all: only the number of rows affected by an insert, update, or delete.
Additionally, you can look at the `DbDataAdapter` type, which includes a `Fill()` method that allows you to download the entire result set into a `DataTable` or `DataSet` object, as well as a number of other abilities.
Finally, this seems like a good time for you to get familiar with Microsoft Docs. This is what documentation is made for: you have the method names; go look them up.
Problem
I am confused with the usage of - ExecuteScalar - ExecuteReader - ExecuteNonQuery when executing SQL queries in my code. When should I use each of these methods?