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Description

This error indicates an attempt to assign a value of an incompatible data type to a variable within a MariaDB SQL statement. It commonly occurs when a string is assigned to a numeric variable, or vice versa, or when a variable expects a specific type (e.g., boolean, date) and receives another, preventing the statement from executing successfully.

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Error Message

Incorrect argument type to variable '%s'

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Known Causes

3 known causes

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Type Mismatch in Assignment

Attempting to assign a value with a data type that is incompatible with the expected type of the variable (e.g., assigning a string literal to an integer user-defined variable).

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Misconfigured System/Session Variable

Setting a system or session variable (e.g., `@@sql_mode`, `@@max_connections`) with a value of an incorrect data type, or a value that cannot be implicitly converted by MariaDB.

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Function Return Type Mismatch

Assigning the result of a function to a variable where the function's return type does not match the variable's expected data type, leading to an assignment error.

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Solutions

3 solutions available

1. Inspect and Correct Variable Usage in Stored Procedures/Functions medium

Identify and correct the data type mismatch between a variable and its assigned value within stored routines.

1

Locate the stored procedure or function that is causing the error. The error message '%s' will often provide a hint to the variable name.

2

Examine the `DECLARE` statements for variables within the routine. Ensure their declared data types are compatible with the values being assigned to them.

DECIMAL(10,2) -- Example of a declared variable type

3

Review the assignment statements (e.g., `SET @variable = value;` or `SELECT column INTO variable FROM ...;`). Pay close attention to the data type of the `value` or the `column` being selected.

SET my_decimal_var = '123.45'; -- Potentially problematic if declared as DECIMAL and assigned a string that cannot be implicitly converted.
SET my_decimal_var = CAST('123.45' AS DECIMAL(10,2)); -- Explicit casting for clarity and safety.

4

If a mismatch is found, either change the variable's declared data type to match the assigned value, or cast the assigned value to the variable's declared type.

IF your_variable_type = 'INT' AND assigned_value IS NOT NULL THEN
  SET your_variable = CAST(assigned_value AS SIGNED INTEGER);
END IF;

5

Recompile or re-execute the stored procedure/function after making the necessary corrections.

CALL your_stored_procedure();

2. Verify Data Types in Dynamic SQL Statements medium

Ensure that variables used within dynamically constructed SQL queries have compatible data types.

1

Identify the part of your application or script that generates and executes dynamic SQL. This is common in application code (PHP, Python, Java) or within MariaDB itself using `PREPARE` and `EXECUTE`.

2

Examine the variables being concatenated into the SQL string or passed as parameters. Check their data types in the application code or within MariaDB's variable context.

SET @sql = CONCAT('SELECT * FROM users WHERE id = ', user_id_variable); -- user_id_variable should be an integer.

3

Ensure that the data types of these variables align with the expected data types of the columns or values they are being compared against or used with in the SQL statement.

SET @sql = CONCAT('SELECT * FROM products WHERE price > ', price_variable); -- price_variable should be a numeric type.

4

If using prepared statements, ensure the data types of the bound parameters match the types expected by the query placeholders.

PREPARE stmt FROM 'SELECT * FROM orders WHERE order_date > ?';
SET @date_val = '2023-10-27';
EXECUTE stmt USING @date_val; -- @date_val should be a DATE or DATETIME type.

5

Perform explicit type casting in your application code or within the dynamic SQL statement if necessary before execution.

SET @sql = CONCAT('SELECT * FROM items WHERE quantity = ', CAST(item_quantity AS CHAR)); -- If item_quantity is numeric and needs to be in a string context.

3. Review User-Defined Functions (UDFs) and External Procedures advanced

Check for type mismatches when passing arguments to or returning values from UDFs or external procedures.

1

Identify any User-Defined Functions (UDFs) or external procedures that are being called and might be involved in the error. The error message might not directly point to the UDF, but the context of its usage will.

2

Examine the `CREATE FUNCTION` or `CREATE PROCEDURE` statements for the UDF/external procedure. Pay close attention to the declared data types of the input parameters and the return type.

CREATE FUNCTION calculate_discount (price DECIMAL(10,2), discount_rate DECIMAL(5,2)) RETURNS DECIMAL(10,2) ...

3

Inspect the code that calls the UDF/external procedure. Verify that the data types of the arguments being passed match the declared parameter types of the function/procedure.

SELECT calculate_discount(product_price, '0.10'); -- product_price and '0.10' should be compatible with DECIMAL.

4

If the UDF is written in a language like C/C++, ensure that the data types expected by the UDF's internal logic align with the data types that MariaDB is providing.

5

Adjust the data types of the arguments when calling the UDF/procedure, or modify the UDF/procedure definition to accommodate the passed data types. Explicit casting is often a good practice.

SELECT calculate_discount(CAST(product_price AS DECIMAL(10,2)), CAST('0.10' AS DECIMAL(5,2)));

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Related Errors

5 related errors

MariaDB Error 1232: Incorrect Variable Type