How to Query Dynamically Referenced Tables in Stored Procedure Functions?

Dynamically Referencing Tables in Stored Procedure Functions

When creating stored procedure functions, you may encounter the need to dynamically specify the name of the table to query. This challenge arises because variables cannot be used directly in the FROM clause of an SQL statement within a function due to restrictions on dynamic SQL.

Prepared Statements as a Workaround

One workaround involves utilizing prepared statements. In stored procedures, prepared statements can be used to construct dynamic SQL queries. However, this approach is not suitable for functions since they prohibit the use of prepared statements.

Stored Procedures with OUT Parameters

To address this limitation, an alternative method involves creating a stored procedure with an OUT parameter that returns the desired value. Here's an example of such a stored procedure:

CREATE PROCEDURE getName
 (IN tableName VARCHAR(50), IN myId INT(11), OUT myName VARCHAR(50))
BEGIN
  SET @GetName = CONCAT('SELECT name INTO @var1 FROM ', tableName, ' WHERE>

Example Usage

To use this stored procedure, you would specify the variable values as follows:

SET @tableName = 'tbl';
SET @myId = 1005;
SET @name = NULL;
CALL getName(@tableName, @myId, @name);
SELECT @name;

This technique effectively allows you to query dynamic table names within stored procedure functions by leveraging stored procedures with OUT parameters.

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