Why Does 'ExecuteReader Requires an Open and Available Connection' Occur, and How Can I Fix It?

In -depth analysis of "ExecuteReader needs to be opened and available" error

"ExecuteReader Requires An Open and Available Connection" error prompt indicates that the database connection has not been established or in a non -activated state when trying to execute database query or retrieval data.

The connection string used in the code uses static variables, which may be the root cause of concurrent connection problem. Static variables keep their value between multiple connections. If multiple users try to connect at the same time, they may cause errors.

The root cause of the error is that the database connection is managed by the connection pool. The connection pool is allocated and released as needed to ensure efficient use of resources. However, when the connection is reused or shared between instances (such as using static variables), the connection pool may be overwhelmed, resulting in errors related to connection.

In order to solve this error, be sure to follow the best practice of ado.net usage:

Avoid using static or shared connections:

Create and release connections within its use range to prevent locking and depletion of resources.
• Using USING statement: Use the USING statement to manage the survival period of the disposable object, including database connection, so as to ensure that they are dealt with correctly after use.
• Use the connection pool: Use the default connection pool provided by Ado.net to efficiently manage the connection without manual management resources.
Avoid database encapsulation:
• Packing the ADO.NET function in a custom class may cause accidental behavior and performance problems.
Through the implementation of these best practices, developers can avoid connecting related errors and ensure strong database interaction.
• The improved RetrievePromotion method

The following is the improved version of the RetrievePromotion method using the connection pool and the correct resource disposal:

In this improved method, it is connected to the range of the RetrievePromotion method to create and release to prevent any concurrent problems or connecting management problems. Note that explicitly open the connection to ensure that the connection has been opened before use.

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