Can we add constraint on variable table?

Can we add constraint on variable table?

The fact #1: Table Variables can have constraints. You can name constraints in Temporary tables, but can’t do it in Table Variables. 2. You can create indexes in Temporary tables, but for Table Variables you can create ONLY Primary Key Constraint (clustered if necessary) and Unique Constraint.

How do you create a variable name in a table in SQL?

To declare a table variable, start the DECLARE statement. The name of table variable must start with at(@) sign. The TABLE keyword defines that used variable is a table variable. After the TABLE keyword, define column names and datatypes of the table variable in SQL Server.

How do you create a variable in a table?

Some useful tips for the table variables

1. DECLARE @TestTable TABLE.
2. (ID INT PRIMARY KEY,
3. Col1 VARCHAR(40) UNIQUE,
4. Col2 VARCHAR(40) NOT NULL,
5. Col3 int CHECK (Col3>=18))
6. INSERT INTO @TestTable.
7. VALUES(1,’Value1′,12 , 20)
8. TRUNCATE TABLE @TestTable.

Can you have more than one unique constraint in SQL?

However, you can have many UNIQUE constraints per table, but only one PRIMARY KEY constraint per table. The following SQL creates a UNIQUE constraint on the “ID” column when the “Persons” table is created:

How to create unique constraint on persons table?

The following SQL creates a UNIQUE constraint on the “ID” column when the “Persons” table is created: To name a UNIQUE constraint, and to define a UNIQUE constraint on multiple columns, use the following SQL syntax: To create a UNIQUE constraint on the “ID” column when the table is already created, use the following SQL:

How to create constraints in a table variable?

Table Variables’ Constraints 1 You can name constraints in Temporary tables, but can’t do it in Table Variables. 2 You can create indexes in Temporary tables, but for Table Variables you can create ONLY Primary Key Constraint… More

Can a unique constraint contain a null value?

None of the fields that are part of the primary key can contain a null value. Some of the fields that are part of the unique constraint can contain null values as long as the combination of values is unique. The syntax for creating a unique constraint using a CREATE TABLE statement in MariaDB is: