| item_id | name | quantity | price | sales_tax | The sales_tax column useS the default value specified in the DEFAULT constraint: SELECT * FROM cart_items Code language: SQL (Structured Query Language) ( sql ) In this example, the INSERT statement doesn’t provide a value for the sales_tax column. VALUES( 'Keyboard', 1, 50) Code language: SQL (Structured Query Language) ( sql ) The following INSERT statement adds a new item to the cart_items table: INSERT INTO cart_items( name, quantity, price) ![]() | sales_tax | decimal(5,2) | NO | | 0.10 | |ĥ rows in set (0.01 sec) Code language: plaintext ( plaintext ) | item_id | int | NO | PRI | NULL | auto_increment | | Field | Type | Null | Key | Default | Extra | The following statement shows the cart_items table: DESC cart_items Code language: SQL (Structured Query Language) ( sql ) The sales_tax column has a default value 0.1 (10%). ) Code language: SQL (Structured Query Language) ( sql ) Sales_tax DEC( 5, 2) NOT NULL DEFAULT 0.1, The following example creates a new table named cart_items with four columns item_id, name, quantity, and sales_tax: CREATE TABLE cart_items If you don’t want to use default values for columns, you can remove the default constraints. MySQL also allows you to add default constraints to the columns of existing tables. Typically, you set the DEFAULT constraints for columns when you create the table. If a column has a DEFAULT constraint and the INSERT or UPDATE statement doesn’t provide the value for that column, MySQL will use the default value specified in the DEFAULT constraint. When you define a column without the NOT NULL constraint, the column will implicitly take NULL as the default value. However, MySQL allows you to set the current date and time ( CURRENT_TIMESTAMP) to the TIMESTAMP and DATETIME columns. ![]() It cannot be a function or an expression. The default_value must be a literal constant, e.g., a number or a string. The type of the default value matches the data type of the column. In this syntax, you specify the DEFAULT keyword followed by the default value for the column. Here’s the syntax of the DEFAULT constraint: column_name data_type DEFAULT default_value Code language: SQL (Structured Query Language) ( sql ) MySQL DEFAULT constraint allows you to specify a default value for a column. Introduction to the MySQL DEFAULT constraint Summary: in this tutorial, you’ll learn about MySQL DEFAULT constraint and how to use it effectively.
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