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Description

This error occurs when an attempt is made to insert or update a NULL value into a column that has been explicitly defined with a NOT NULL constraint. MySQL prevents the operation to maintain data integrity, as the column is designed to always contain a value.

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Error Message

Column '%s' cannot be null

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Known Causes

4 known causes

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Missing Value in INSERT

An INSERT statement did not provide a value for a NOT NULL column, leading MySQL to implicitly try to assign NULL.

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Explicit NULL Assignment

An INSERT or UPDATE statement explicitly attempted to set a NOT NULL column's value to NULL.

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No Default Value Defined

A NOT NULL column without a specified default value was omitted in an INSERT, causing MySQL to attempt to assign NULL.

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Data Import Mismatch

During data import or migration, source data contained NULL values for columns that are defined as NOT NULL in the target table.

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Solutions

3 solutions available

1. Provide a Default Value for the Column easy

Alter the table to add a default value to the non-nullable column.

1

Identify the table and the specific column that is causing the error.

2

Connect to your MySQL server using a client like `mysql` command-line or a GUI tool.

3

Execute an `ALTER TABLE` statement to add a `DEFAULT` constraint to the column. Replace `your_table_name`, `your_column_name`, and `default_value` with your actual values. The `default_value` should be of the correct data type for the column.

ALTER TABLE your_table_name MODIFY COLUMN your_column_name datatype NOT NULL DEFAULT default_value;

4

If the column is a string type, enclose the default value in single quotes. For example, `DEFAULT 'N/A'`. If it's a numeric type, do not use quotes. For date/time types, use appropriate functions like `CURRENT_TIMESTAMP`.

2. Modify Application Logic to Always Provide a Value medium

Update your application code to ensure a non-null value is always supplied for the column.

1

Review your application's code that inserts or updates data into the affected table.

2

Locate all instances where data is being sent to the database for the table in question.

3

Ensure that when you are constructing your SQL `INSERT` or `UPDATE` statements, you are explicitly providing a value for the non-nullable column. Do not omit it or pass a `NULL` value.

Example (Conceptual SQL):
INSERT INTO your_table_name (column1, your_column_name, column3) VALUES ('value1', 'provided_value', 'value3');

UPDATE your_table_name SET your_column_name = 'updated_value' WHERE id = 1;

4

If the value is dynamic, implement logic in your application to determine and assign a suitable value before sending it to the database.

3. Temporarily Allow NULL Values (with Caution) medium

Alter the column to allow NULLs temporarily, then address the data and re-apply the NOT NULL constraint.

1

Identify the table and the non-nullable column.

2

Connect to your MySQL server.

3

Alter the column to allow NULL values. Replace `your_table_name`, `your_column_name`, and `datatype`.

ALTER TABLE your_table_name MODIFY COLUMN your_column_name datatype NULL;

4

Now, you can perform operations that might have previously failed due to the non-nullable constraint. It is crucial to address the data that is causing the issue.

5

Update the rows that have `NULL` in this column with appropriate values. This might involve a data migration script or manual updates.

UPDATE your_table_name SET your_column_name = 'some_default_or_derived_value' WHERE your_column_name IS NULL;

6

Once all `NULL` values are resolved, re-apply the `NOT NULL` constraint. Ensure you specify the correct `datatype`.

ALTER TABLE your_table_name MODIFY COLUMN your_column_name datatype NOT NULL;

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Related Errors

5 related errors

MySQL Error 3673: Non-Nullable Column Value