SQL Server Designer Implementation constraints

I. INTRODUCTION to CONSTRAINT Types

Second, create a data table

Iii. creating PRIMARY KEY constraints and non-null constraints

Iv. Creating a UNIQUE constraint

Select any column, right--index/Key

Click Add to generate Ix_employees*,

Type is set to "unique key",

Then select the columns you want to constrain,

Finally, the index name is modified.

Five, check the constraints

Case One

Case Two

Vi. Default Constraints

Seven, FOREIGN KEY constraints

Viii. Effects of restraint

Department table

Employee table

CHECK constraints

Non-null constraint

Unique constraint

FOREIGN KEY constraints

FOREIGN KEY constraints

Nine, Cascade Delete

When you delete the primary key table data, the foreign key table data associated with it is also deleted.

Delete data from department table Depid to 1

The Employee table foreign key Empdeptid 1 has also been deleted.

SQL Server Designer Implementation constraints