SQL Alter Column Default
Value
Alter Column Default Value in SQL Server is used with Create
Table Statement. The default value will be set as per specified column. The
use of default value is specified when insert is performed, but value in
the column is not set.
Understand with Example
In this Tutorial, the query create a table 'Stu_Table' using a create
statement. The insert into in SQL Query add the records to
table. The Describe table show you the Table attribute like field,
data type etc.
Create Table Stu_Table
create table Stu_Table( Stu_Id integer(2), Stu_Name varchar(15),
Stu_Class varchar(10))
|
Insert data into Stu_Table
insert into Stu_Table (Stu_Id, Stu_Name) values(1,'Komal');
insert into Stu_Table (Stu_Id, Stu_Name) values(2,'Ajay');
insert into Stu_Table (Stu_Id, Stu_Name) values(3,'Rakesh');
insert into Stu_Table (Stu_Id, Stu_Name) values(4,'Bhanu');
insert into Stu_Table (Stu_Id, Stu_Name) values(5,'Santosh');
|
Stu_Table
+--------+----------+-----------+
| Stu_Id | Stu_Name | Stu_Class |
+--------+----------+-----------+
| 1 | Komal | 10 |
| 2 | Ajay | 10 |
| 3 | Rakesh | 10 |
| 4 | Bhanu | 10 |
| 5 | Santosh | 10 |
+--------+----------+-----------+
|
Describe Stu_Table
+-----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+-------------+------+-----+---------+-------+
| Stu_Id | varchar(10) | YES | | | |
| Stu_Name | varchar(10) | YES | | NULL | |
| Stu_Class | varchar(5) | YES | | NULL | |
+-----------+-------------+------+-----+---------+-------+
|
Alter column Column
Default Query
The Alter Table Keywords modify
table'Stu_Table' and MODIFY keyword modify the data type of field
Stu_Id (varchar(10)) to Stu_Id(int(3)) and set the default value for this
field is set '10'.Whenever you leave a blank value in Stu_Id, This field
would take default value of '10'.
ALTER TABLE Stu_Table MODIFY Stu_Id int(3) Default '10'
|
Describe Stu_Table
+-----------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| Stu_Id | int(3) | No | | 10 | |
| Stu_Name | varchar(10) | YES | | NULL | |
| Stu_Class | varchar(5) | YES | | NULL | |
+-----------+--------------+------+-----+---------+-------+
|
|
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