Does SqlConnection Close in a 'Using' Block on Return or Exception?

using Closing behavior of SqlConnection in statement block: return values ​​and exceptions

using Will the statement block be closed SqlConnection on return or exception? Let’s explore this behavior:

First question:

In the following code block:

<code class="language-csharp">using (SqlConnection connection = new SqlConnection(connectionString))
{
    connection.Open();

    string storedProc = "GetData";
    SqlCommand command = new SqlCommand(storedProc, connection);
    command.CommandType = CommandType.StoredProcedure;
    command.Parameters.Add(new SqlParameter("@EmployeeID", employeeID));

    return (byte[])command.ExecuteScalar();
}</code>

Answer: Yes, the connection will be closed.

The

using statement block ensures that IDisposable resources (i.e. SqlConnection) are properly released even in the event of an early return. When the code exits the using block, the Dispose() method (which closes the connection) is automatically called.

Second question:

In this code block:

<code class="language-csharp">try
{
    using (SqlConnection connection = new SqlConnection(connectionString))
    {
        int employeeID = findEmployeeID();

        connection.Open();
        SqlCommand command = new SqlCommand("UpdateEmployeeTable", connection);
        command.CommandType = CommandType.StoredProcedure;
        command.Parameters.Add(new SqlParameter("@EmployeeID", employeeID));
        command.CommandTimeout = 5;

        command.ExecuteNonQuery();
    }
}
catch (Exception) { /*处理错误*/ }</code>

Answer: Yes, the connection will still be closed.

Even if an exception is thrown in the using statement block, the code will immediately jump to the catch block, and when exiting the using statement block, SqlConnection will still be released.

Summary:

Regardless of whether the using statement block exits via a return value or an exception, SqlConnection will always be closed to ensure resource cleanup.

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