How to use DEFAULT Constraint on CREATE TABLE In MySQL

We can add a DEFAULT constraint while creating a table in MySQL.

Syntax

CREATE TABLE table_name (
   column1 data_type DEFAULT default_value,
   column2 data_type DEFAULT default_value,   ... );

Example

CREATE TABLE customers (
  id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
  name VARCHAR(255) NOT NULL,
  email VARCHAR(255) DEFAULT 'example@domain.com',
  city VARCHAR(50) DEFAULT 'Unknown'
);

MySQL DEFAULT Constraint

The MySQL DEFAULT constraint returns the default value for a table column. The DEFAULT value of a column is a value used in the case, when there is no value specified by the user.

To use this function there should be a DEFAULT value assigned to the column. Otherwise, it will generate an error.

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Syntax

DEFAULT (column_name)...

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Key TakeAways:

Compatibility with Data Types: The default value must be compatible with the column’s data type. Expression Defaults (MySQL 8.0.13+): Starting from MySQL 8.0.13, you can use expressions as default values. Limitations on BLOB and TEXT Columns: Prior to MySQL 8.0.13, BLOB and TEXT columns cannot have a DEFAULT value due to their nature of storing large amounts of data. However, from MySQL 8.0.13 and onward, this restriction has been lifted for certain expressions like CURRENT_TIMESTAMP. NOT NULL Columns: If a column is set to NOT NULL without a DEFAULT value explicitly defined, and you try to insert a row without specifying a value for this column, MySQL will throw an error. Defining a DEFAULT value can prevent such errors....