How to Properly Close a SqlDataReader in C#?
Closing a SqlDataReader correctly prevents memory leaks, connection issues, and unclosed resources. Here’s the best way to do it.
Use 'using' to Auto-Close
Using using statements ensures SqlDataReader and SqlConnection are closed even if an exception occurs.
Example
using (SqlConnection conn = new SqlConnection(connectionString))
{
conn.Open();
using (SqlCommand cmd = new SqlCommand("SELECT * FROM Users", conn))
using (SqlDataReader reader = cmd.ExecuteReader())
{
while (reader.Read())
{
Console.WriteLine(reader["Username"]);
}
} // ✅ Auto-closes reader here
} // ✅ Auto-closes connection here
This approach auto-closes resources when done and it is cleaner and less error-prone than manual closing.
⚡ Alternative: Manually Close in finally Block
If you need explicit control, you can manually close it inside a finally block.
SqlDataReader? reader = null;
try
{
using SqlConnection conn = new SqlConnection(connectionString);
conn.Open();
using SqlCommand cmd = new SqlCommand("SELECT * FROM Users", conn);
reader = cmd.ExecuteReader();
while (reader.Read())
{
Console.WriteLine(reader["Username"]);
}
}
finally
{
reader?.Close(); // ✅ Closes reader if it was opened
}
This is slightly more error prone if you forget to add a finally block. But might make sense when you need to handle the reader separately from the command or connection.