MySQL Database Management System > MySQL Constraints

MySQL Constraints

25.5k

Column limitations limit the types of data that can be entered into a column. Although the data in each individual column does not have to be unique, the combination of data in the PRIMARY KEY columns of a specific table must be unique.

In MySQL, the syntax for defining a unique constraint with an ALTER TABLE statement is: TABLE CHANGE constraint name UNIQUE (column1, column2,... column n); table name ADD CONSTRAINT constraint name UNIQUE (column1, column2,... column n); table name.

SQL constraints are rules that a table's data must follow. The type of data that can be entered into a table is limited by constraints. This ensures that the data in the table is accurate and reliable. The action is cancelled if there is a conflict between the constraint and the data action.

SQL constraints are guidelines for how data in a table should be handled. The type of data that can be put into a table is limited by constraints. This guarantees the table's data's accuracy and consistency. The data action is cancelled if there is a conflict between the constraint and the data action.

In SQL, the CHECK constraint is an example of an integrity constraint. The CHECK constraint sets a search criteria that will be used to verify the value entered into a row. If the result of a search condition is FALSE for any row of the table, the constraint is broken (but not if result is UNKNOWN or TRUE).

Learner's Ratings

4.3

Overall Rating

  • 60%
  • 28%
  • 2%
  • 0%
  • 10%

Reviews

V
vj tricks
5

This course is very good

S
Sanjeev Rana
5

Please provide course notes

A
Ankit Patel
5

Thank you learnvern and learnvern is best platfrom a lern a new skill. again thank you.

Y
Yadav Aakash
5

learnvern doing greate job...Thank you teacher's content team.

U
Utkarsh Chimote
5

Awesome really great teaching and this is good platform for we are poor peoples😍🤗

P
parth joshi
5

Awasome really great ......but kindly resolve your payment error as soon as possible pls

T
Tushar Gayakwad
5

Really great sir

K
Karan kadam
5

thank you sir!!!

S
savnesh daksh
5

Good

S
Sparsh Gaur
4

arey kiske barabar

Show More
Recommended Courses
Course Content
Enroll For Free