What are the Limitations of the SQL Server IN Clause?

Exploring the Limits of the IN Clause in SQL Server

The SQL Server IN clause allows you to test if a column value matches any of the values specified in a list of expressions. While this clause is versatile, it has certain limitations, one of which is the number of values it can accommodate.

Is There a Limit?

Yes, there is a limit to the number of values that can be included in the IN clause. However, Microsoft does not provide a specific number but rather states that it lies "in the thousands."

Resource Consumption and Error Codes

Including an excessive number of values within the IN clause can strain resources and trigger errors 8623 or 8632. These errors indicate that the query's complexity has exceeded the system's capacity.

Error Details

Error 8623 occurs when the system expends internal resources in an attempt to generate a query plan for a complex or resource-intensive query. Error 8632 arises when the query contains intricate expressions that exceed internal limits.

Workaround

To circumvent the limit, Microsoft recommends storing IN list items in a table and employing a SELECT subquery within the IN clause. This approach offloads the burden from the IN clause itself and reduces the likelihood of resource exhaustion or errors.

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