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Description

Error 1415 indicates that a stored function or trigger, and in some specific contexts a stored procedure, has attempted to execute a `SELECT` statement that would return a result set. MariaDB stored functions and triggers are designed to return a single scalar value or have side effects, and explicitly disallow returning tabular data.

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Error Message

Not allowed to return a result set from a %s

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Known Causes

3 known causes

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Stored Function Returns Result Set

A `CREATE FUNCTION` or `ALTER FUNCTION` definition includes a `SELECT` statement that produces a result set, which is not permitted for functions.

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Trigger Returns Result Set

A `CREATE TRIGGER` or `ALTER TRIGGER` definition contains a `SELECT` statement that attempts to return tabular data, which is disallowed within triggers.

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Debugging SELECT Statement Left In

A `SELECT` statement used for debugging purposes was not removed from a stored function or trigger before deployment, leading to an attempt to return a result set.

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Solutions

3 solutions available

1. Remove SELECT Statements from Stored Procedures easy

Eliminate any standalone SELECT statements that aren't part of an INSERT, UPDATE, or DELETE operation within the stored procedure.

1

Identify the stored procedure causing the error. You can often pinpoint this by looking at the call stack or the application code that invokes the procedure.

2

Edit the stored procedure's definition. Locate any `SELECT` statements that are not part of an `INSERT INTO ... SELECT`, `UPDATE ... SET ... WHERE EXISTS (SELECT ...)` or similar constructs. These are the statements that are returning result sets.

-- Example of a problematic SELECT statement within a procedure:
-- SELECT * FROM my_table WHERE some_condition;

3

Remove or comment out these standalone `SELECT` statements.

-- Example of a removed SELECT statement:
-- SELECT * FROM my_table WHERE some_condition; -- Removed due to Error 1415

4

If you need to retrieve data, consider using an `OUT` parameter or a temporary table to store the results and then select from that.

5

Recreate the stored procedure with the modified definition.

DELIMITER //
CREATE OR REPLACE PROCEDURE my_procedure (...) BEGIN
  -- ... other logic ...
  -- Removed SELECT statement
END //
DELIMITER ;

2. Return Results via OUT Parameters medium

Modify the stored procedure to return data using `OUT` parameters instead of direct `SELECT` statements.

1

Identify the stored procedure and the data you intend to return.

2

Alter the stored procedure to include `OUT` parameters for each piece of data you want to return. The data type of the `OUT` parameter should match the data you are retrieving.

-- Original procedure signature (example):
-- CREATE PROCEDURE my_procedure (...)

-- Modified procedure signature:
DELIMITER //
CREATE OR REPLACE PROCEDURE my_procedure (..., OUT param1 INT, OUT param2 VARCHAR(255)) BEGIN
  -- ... logic to populate param1 and param2 ...
END //
DELIMITER ;

3

Inside the procedure, use `SELECT ... INTO` statements to assign the retrieved data to the `OUT` parameters.

DELIMITER //
CREATE OR REPLACE PROCEDURE my_procedure (..., OUT param1 INT, OUT param2 VARCHAR(255)) BEGIN
  SELECT column1 INTO param1 FROM my_table WHERE id = 1;
  SELECT column2 INTO param2 FROM another_table WHERE related_id = param1;
END //
DELIMITER ;

4

When calling the procedure from your application or another SQL statement, you will need to declare session variables to capture the `OUT` parameter values.

CALL my_procedure(..., @result1, @result2);
SELECT @result1, @result2;

3. Use Temporary Tables to Store and Retrieve Results medium

Store the results of a `SELECT` statement in a temporary table within the procedure and then select from that temporary table.

1

Identify the stored procedure and the `SELECT` statement that needs to be executed.

2

Within the stored procedure, create a temporary table to hold the results. Use `CREATE TEMPORARY TABLE`.

DELIMITER //
CREATE OR REPLACE PROCEDURE my_procedure (...) BEGIN
  CREATE TEMPORARY TABLE temp_results (
    column_a INT,
    column_b VARCHAR(50)
  );
  -- ... other logic ...
END //
DELIMITER ;

3

Populate the temporary table with the results of your `SELECT` statement using `INSERT INTO ... SELECT`.

DELIMITER //
CREATE OR REPLACE PROCEDURE my_procedure (...) BEGIN
  CREATE TEMPORARY TABLE temp_results (
    column_a INT,
    column_b VARCHAR(50)
  );
  INSERT INTO temp_results (column_a, column_b)
  SELECT col1, col2 FROM my_table WHERE some_condition;
  -- ... other logic ...
END //
DELIMITER ;

4

If your application or calling code needs to see these results, you will need to call the procedure and then `SELECT` from the temporary table. Note that temporary tables are session-specific and are dropped when the session ends.

CALL my_procedure(...);
SELECT * FROM temp_results;

5

Ensure the temporary table is dropped or cleaned up if it's no longer needed within the procedure, though this is often handled automatically when the session ends.

DROP TEMPORARY TABLE IF EXISTS temp_results;

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Related Errors

5 related errors

MariaDB Error 1415: Stored Routine Result Set