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Description

This error occurs when attempting to create or alter a stored procedure, function, or trigger that contains two or more variables or parameters with the identical name within the same scope. It indicates a naming conflict that prevents the routine definition from being accepted by MariaDB.

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Error Message

Duplicate variable: %s

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Known Causes

3 known causes

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Duplicate Local Variable Declaration

You have declared two or more local variables with the same name within the `DECLARE` section of a `BEGIN...END` block in your stored routine.

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Conflicting Routine Parameters

A parameter name specified for a stored procedure or function is identical to another parameter or a local variable declared within the same routine.

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Accidental Redeclaration

A variable was unintentionally declared more than once due to a copy-paste error, typo, or oversight in a complex or lengthy routine definition.

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Solutions

3 solutions available

1. Rename Duplicate Variable easy

Identify and rename the conflicting variable within the stored routine.

1

Examine the stored routine (stored procedure or function) where the error is occurring. The error message 'Duplicate variable: %s' will typically include the name of the duplicate variable.

2

Locate the declaration of the variable that is causing the duplication. This is usually at the beginning of the routine within a `DECLARE` statement.

3

Rename one of the instances of the duplicate variable to a unique name. For example, if you have two variables named `my_var`, rename one to `my_var_1` or `temp_var`.

DECLARE my_var INT;
-- ... later in the routine ...
DECLARE my_var_1 INT; -- Renamed from my_var

4

Ensure that all references to the renamed variable within the stored routine are updated accordingly.

5

Recreate or alter the stored routine with the corrected variable names.

ALTER PROCEDURE your_procedure_name ...;
-- or
CREATE OR REPLACE PROCEDURE your_procedure_name ...;

2. Review Variable Scope and Declaration medium

Ensure variables are declared correctly within their intended scope.

1

Carefully review the `DECLARE` statements within your stored routine. MariaDB allows local variables within `BEGIN...END` blocks.

2

Check if a variable with the same name is declared in an outer scope and then redeclared in an inner scope without proper handling, or if it's declared multiple times within the same scope.

DELIMITER //
CREATE PROCEDURE example_proc() BEGIN
  DECLARE counter INT DEFAULT 0;
  -- Some logic here
  BEGIN
    DECLARE counter INT DEFAULT 10; -- This will cause the error if not handled
    -- ...
  END;
END //
DELIMITER ;

3

If a variable is intended to be accessible across different `BEGIN...END` blocks, declare it in the outermost scope. If it's specific to an inner block, ensure it has a unique name or is managed by the outer scope's variable.

DELIMITER //
CREATE PROCEDURE example_proc() BEGIN
  DECLARE counter INT DEFAULT 0;
  -- Some logic here
  BEGIN
    SET counter = counter + 5; -- Using the outer scope variable
    -- ...
  END;
END //
DELIMITER ;

4

Recreate or alter the stored routine after correcting the variable declarations and scoping.

ALTER PROCEDURE your_procedure_name ...;
-- or
CREATE OR REPLACE PROCEDURE your_procedure_name ...;

3. Use Temporary Table Columns as Variables (Advanced) advanced

Leverage temporary table columns if variables are being used in a way that mimics temporary storage.

1

Analyze if the duplicate variables are being used to store intermediate results or data that could be more effectively managed using a temporary table.

2

Instead of declaring multiple variables, create a temporary table with appropriate columns to hold the data.

CREATE TEMPORARY TABLE temp_data (
  id INT AUTO_INCREMENT PRIMARY KEY,
  value1 VARCHAR(255),
  value2 INT
);

3

Insert data into the temporary table and then query from it as needed within your stored routine. This avoids the need for numerous local variables.

INSERT INTO temp_data (value1, value2) VALUES ('some_value', 123);

4

Ensure the temporary table is dropped when no longer needed, typically at the end of the stored routine or session.

DROP TEMPORARY TABLE IF EXISTS temp_data;

5

This approach can simplify complex routines and reduce the likelihood of variable naming conflicts.

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Related Errors

5 related errors

MariaDB Error 1331: Duplicate Stored Routine Variable