Does a `Using` Block Automatically Close an Open SQL Connection?

Does the End of Using Close an Open SQL Connection?

When utilizing a SQLConnection object within a Using block, it is common practice to explicitly call the Close() method before exiting the block. However, this raises the question: Is this step necessary? Does the conclusion of the Using block automatically handle connection closure?

The Behavior of Using Blocks

When an object is wrapped in a Using block, the Dispose() method is invoked on the object upon exiting the block. In the case of a SqlConnection, the Dispose() method performs the following actions:

• Closes the connection, if open
• Releases all associated resources

Why Explicitly Calling Close May Be Unnecessary

Given the behavior of Using blocks, it becomes evident that explicitly calling Close() is redundant. The Using block will automatically invoke Dispose(), which will handle connection closure as part of its routine.

Code Sample

The following code sample illustrates the behavior:

using (var cn = new System.Data.SqlClient.SqlConnection())
{
    cn.Open();
    // Do operations with commands and datareaders

    // Explicitly calling Close() is unnecessary
    // cn.Close();
}

By not explicitly calling Close() within the Using block, we ensure that resources are managed and the connection is closed automatically upon exiting the block.

Conclusion

In summary, the end of a Using block handles the closure of an open SQLConnection. Explicitly calling Close() is therefore unnecessary and may introduce redundancy in the code.

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