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  • What is the mysql Constraints?

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    Welcome to FindNerd,
    Today we are going to discuss about MySQL Constraints.
    Firstly let know what is Constraints in MySQL ?

    Constraints:- Constraints are the utilities that restrict ingression of data into the table if the designated condition is not consummated.

    Constraints have many type in MySQL

    There are given bellow:

    1- Primary Key
    2- Unique Key
    3- Foreign Key
    4- Not null

    1-Primary Key:- Primary key averts duplicate ingress.
    Primary key can never be null value.
    Primary key signifies inside a table there is only one field can be declared primary.

    2-Unique Key:- Unique Key will not enter a duplicate value in the field.
    Unique key can be null value in the field.
    Unique key also called column based constraint.

    3-Foreign Key:- Foreign key is also column based constraint.
    Foreign key depends on primary key.
    A column is called Foreign key when Foreign key refers to the primary key column of another table.

    4-Not null :- Not null will not allow entering null Value in the field.
    Not null allow entering duplicate in the field.

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