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Description

MySQL Error 1313 indicates that a `RETURN` statement has been used in an invalid context, specifically within a `STORED PROCEDURE`. The `RETURN` keyword is exclusively reserved for `FUNCTIONS` in MySQL, which are designed to return a single scalar value.

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Error Message

RETURN is only allowed in a FUNCTION

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Known Causes

3 known causes

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Using RETURN in a Stored Procedure

This error occurs when a `RETURN` statement is explicitly included within the body of a `CREATE PROCEDURE` definition instead of a `CREATE FUNCTION`.

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Misunderstanding Routine Types

Developers might confuse the distinct purposes and syntax of MySQL `FUNCTIONS` (which return a value) and `PROCEDURES` (which perform actions and do not return a value via `RETURN`).

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Copying Function Logic to a Procedure

Reusing or adapting code snippets that contain `RETURN` from an existing `FUNCTION` into a `PROCEDURE` definition without modification will trigger this error.

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Solutions

3 solutions available

1. Remove RETURN from Stored Procedure easy

The RETURN statement is not permitted in Stored Procedures; it's exclusively for Functions.

1

Identify the stored procedure causing the error. This is usually evident from the error message or logs.

2

Open the stored procedure definition in your MySQL client or editor.

3

Locate and remove any `RETURN` statements within the stored procedure. If you intended to return a value, consider using an `OUT` parameter instead.

DELETE FROM your_stored_procedure WHERE statement = 'RETURN value;'; -- Conceptual example, you'll edit the procedure definition directly

4

Save the modified stored procedure.

5

Re-execute the operation that triggered the error. The error should now be resolved.

2. Convert Stored Procedure to a Function (if value return is intended) medium

If the intention was to return a value, convert the stored procedure into a SQL Function.

1

Examine the stored procedure to understand what value it was intended to return and how it was being used.

2

Create a new SQL Function with a `RETURNS` clause specifying the data type of the value to be returned.

CREATE FUNCTION your_function_name (param1 INT, param2 VARCHAR(255)) RETURNS INT
BEGIN
    -- Your logic here
    DECLARE result INT;
    -- ... calculate result ...
    RETURN result;
END;

3

Migrate the logic from the stored procedure into the body of the new function. Ensure any `RETURN` statements are correctly placed and return the declared data type.

4

If the original stored procedure was called directly, you will now call the function like a built-in function (e.g., `SELECT your_function_name(1, 'test');`).

5

Drop the original stored procedure once you have confirmed the function works as expected.

DROP PROCEDURE your_stored_procedure_name;

3. Utilize OUT Parameters for Value Passing medium

For Stored Procedures that need to communicate a value back, use OUT parameters.

1

Identify the stored procedure and the `RETURN` statement that is causing the error.

2

Alter the stored procedure definition to include an `OUT` parameter. This parameter will hold the value you intend to 'return'.

ALTER PROCEDURE your_stored_procedure_name (IN param1 INT, IN param2 VARCHAR(255), OUT output_value INT)
BEGIN
    -- Your logic here
    -- ... calculate value ...
    SET output_value = calculated_value;
END;

3

Replace the `RETURN` statement with a `SET` statement that assigns the desired value to the `OUT` parameter.

SET output_value = some_result;

4

When calling the stored procedure, you will need to provide a session variable (or a variable in your application code) to receive the value from the `OUT` parameter.

CALL your_stored_procedure_name(1, 'test', @result_variable);
SELECT @result_variable;

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Related Errors

5 related errors

MySQL Error 1313: RETURN in Stored Procedure