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Description

MySQL Error 1048 indicates an attempt to store a NULL value in a table column that has been defined with a NOT NULL constraint. This commonly occurs during INSERT or UPDATE operations when a required field is omitted or explicitly set to NULL, violating the column's data integrity rules.

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Error Message

Column '%s' cannot be null

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Known Causes

3 known causes

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Missing Value in INSERT

An INSERT statement did not specify a value for a NOT NULL column, causing MySQL to implicitly attempt to insert NULL.

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Explicit NULL Assignment

An INSERT or UPDATE statement explicitly assigned NULL to a column that is defined with a NOT NULL constraint.

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Application Data Handling Error

The application code is sending NULL values to the database for columns that require non-null data, due to incorrect data processing or validation.

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Solutions

5 solutions available

1. Provide Value for NOT NULL Column easy

Include the required column in your INSERT

1

Check which columns are NOT NULL

DESCRIBE your_table;

2

Include all NOT NULL columns in INSERT

-- If 'email' is NOT NULL:
INSERT INTO users (name, email) VALUES ('John', 'john@example.com');

2. Set Default Value for Column medium

Add default value to avoid NULL issues

1

Add default value to existing column

ALTER TABLE your_table MODIFY COLUMN column_name VARCHAR(255) NOT NULL DEFAULT '';

2

Add default value for numeric column

ALTER TABLE your_table MODIFY COLUMN status INT NOT NULL DEFAULT 0;

3

Add default timestamp

ALTER TABLE your_table MODIFY COLUMN created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP;

3. Allow NULL Values medium

Change column to allow NULL

1

Remove NOT NULL constraint

ALTER TABLE your_table MODIFY COLUMN column_name VARCHAR(255) NULL;

2

Check current column definition first

SHOW CREATE TABLE your_table;

4. Fix Application Code medium

Ensure code sends values for required fields

1

Check for NULL/undefined values before insert

// JavaScript/Node.js example:
const email = userData.email || 'default@example.com';
const query = 'INSERT INTO users (name, email) VALUES (?, ?)';
connection.query(query, [name, email]);

2

PHP example with null coalescing

$email = $userData['email'] ?? 'default@example.com';
$stmt = $pdo->prepare('INSERT INTO users (name, email) VALUES (?, ?)');
$stmt->execute([$name, $email]);

5. Handle UPDATE Setting NULL easy

Fix UPDATE statements that try to set NULL

1

Use empty string instead of NULL for text columns

-- Wrong:
UPDATE users SET name = NULL WHERE id = 1;

-- Right (if column is NOT NULL):
UPDATE users SET name = '' WHERE id = 1;

2

Use COALESCE to handle potential NULLs

UPDATE users SET name = COALESCE(@newName, name) WHERE id = 1;

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Related Errors

5 related errors

MySQL Error 1048: Column Cannot Be Null