CHECK Constraint in MySQL
The CHECK constraint in MySQL allows you to define a condition that data must satisfy before it can be inserted into or updated in a table. For example, suppose you have a student’s age field defined in a CREATE TABLE…
Category MySQL
FOREIGN KEY in MySQL
A FOREIGN KEY in MySQL is a constraint that establishes a link between two tables. It simply connects a column in one table to the PRIMARY KEY or UNIQUE KEY in another table. A FOREIGN KEY is a column or…
PRIMARY KEY in MySQL
A PRIMARY KEY in MySQL is a constraint that uniquely identifies each row in a database table. It ensures that the values in a specified column or combination of columns are unique and not NULL. A table can contain only…
MySQL UNIQUE Constraint
A UNIQUE constraint in MySQL ensures that all values in a column or a group of columns are distinct across every row in a table. In simple words, the UNIQUE constraint prevents duplicate data from being inserted into a column…
NOT NULL Constraint in MySQL
The NOT NULL constraint is one of the most commonly used constraints in MySQL that prevents NULL values from being stored in a column. This constraint ensures that every row in the table must contain a value for that column.…