📋

Description

Error 1138 indicates that a NULL value has been used in a context where it is not permitted or makes no logical sense. This typically occurs when violating a `NOT NULL` column constraint or when a function or operation expects a non-NULL argument.

💬

Error Message

Invalid use of NULL value

🔍

Known Causes

3 known causes

⚠️

NOT NULL Constraint Violation

Attempting to insert or update a column with a NULL value when the column is explicitly defined with a `NOT NULL` constraint.

⚠️

Incorrect Function Arguments

Passing a NULL value as an argument to a built-in function, stored procedure, or expression that requires a non-NULL input.

⚠️

Implicit NULL in Expressions

Using a NULL value within an arithmetic operation or comparison where the resulting NULL is then used in a context that disallows it.

🛠️

Solutions

3 solutions available

1. Identify and Correct the Offending Query medium

Pinpoint the SQL statement causing the issue and adjust it to handle NULLs appropriately.

1

Examine your application logs or MySQL error logs to find the specific SQL query that triggered the error.

grep "MySQL Error 1138" /path/to/your/mysql/error.log

2

Analyze the query. Look for operations that might be invalid with NULL values. Common culprits include arithmetic operations on NULLs (e.g., `NULL + 5`), string concatenations where NULL is not expected, or comparisons that implicitly try to treat NULL as a specific value.

SELECT column1, column2 FROM your_table WHERE some_column IS NULL AND another_column > 10;

3

Modify the query to explicitly handle NULL values using functions like `IFNULL()`, `COALESCE()`, or by adding `IS NULL` or `IS NOT NULL` checks.

SELECT IFNULL(column1, 0) AS column1, column2 FROM your_table WHERE some_column IS NULL AND another_column > 10;

4

If the issue is with data insertion or updates, ensure that the values being inserted or updated are compatible with the column's data type and constraints. If a column expects a non-NULL value, provide one.

INSERT INTO your_table (non_nullable_column, nullable_column) VALUES ('some_value', NULL);

2. Adjust Table Schema for Nullability medium

Modify the table definition to allow NULLs where appropriate or enforce non-NULL constraints.

1

Identify the table and column involved in the error. This can often be inferred from the problematic query.

DESCRIBE your_table;

2

If a column is currently defined as `NOT NULL` but your application legitimately needs to store NULLs there, alter the table to allow NULLs.

ALTER TABLE your_table MODIFY column_name data_type NULL;

3

Conversely, if a column is defined as `NULL` but the operation causing the error implicitly requires a non-NULL value, you might need to ensure data is provided or change the column to `NOT NULL` and handle the missing data in your application logic.

ALTER TABLE your_table MODIFY column_name data_type NOT NULL;

3. Use `IFNULL` or `COALESCE` for Default Values easy

Replace NULL values with a default in queries where NULL is not acceptable for an operation.

1

Identify the specific column or expression in your query that is returning NULL and causing the error.

SELECT column_that_might_be_null * 5 FROM your_table;

2

Wrap the problematic column or expression with `IFNULL()` or `COALESCE()` to provide a default value if it's NULL. `IFNULL(expression, default_value)` returns `default_value` if `expression` is NULL, otherwise it returns `expression`. `COALESCE(expression1, expression2, ...)` returns the first non-NULL expression.

SELECT IFNULL(column_that_might_be_null, 0) * 5 FROM your_table;

3

Ensure the default value you provide is of a compatible data type for the operation being performed.

SELECT COALESCE(string_column, '') || ' - additional text' FROM your_table;

🔗

Related Errors

5 related errors

MySQL Error 1138: Invalid NULL Value Usage