SQL Beginner Tutorial Study (v)

The 1.DEFAULT constraint is used to insert a default value into a column.

CREATE TABLE Orders
(
Id_o int not NULL,
OrderNo int not NULL,
id_p int,
OrderDate date DEFAULT GETDATE ()
)

2. Create a DEFAULT constraint for the "City" column if the table already exists

ALTER TABLE Persons
ALTER COLUMN City SET DEFAULT ' Sandnes '

Revoke

ALTER TABLE Persons
ALTER COLUMN City DROP DEFAULT

3.CREATE INDEX Instance

This session creates a simple index, named "Personindex," in the LastName column of the person table:

If you want to index more than one column, you can list the names of these columns in parentheses, separated by commas:

CREATE INDEX personindexon person (LastName, FirstName)
4. Add a column

ALTER TABLE Personsalter COLUMN Birthday Year

Note that the data type of the "Birthday" column is year, which can hold 2-bit or 4-bit formats .

SQL Beginner Tutorial Study (v)