SQL Alter Column Not Null
The Column Not Null in SQL is used when you want the column should not
be null in your table.
Understand with Example
The Tutorial express you a elaborative example on SQL Alter Column Not
Null. The example create a Table Stu_Table is created using a create
table. The insert into statement add records or rows to
the table 'Stu_Table'. The Describe Table show you the table
attribute like field name, data type, null etc. The created table have
null values in field name. The 'Yes' null specify the field value can be
empty or Optional.
Now You want the specific data field value not to be empty. Once
you define your field name not to be null, It is mandatory to insert the
value into specific field name. The Alter Table modify and change
the table 'Stu_Table'. Modify keyword in SQL Query modify the
null value for the column 'Stu_Id' to not null. It is advisable for you to
insert value into specified field.
The Describe Table show you a modified field null value in table
'Stu_Table'.
Create Table Stu_Table
create table Stu_Table(Stu_Id varchar(2), Stu_Name varchar(10),
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(2) | YES | | | |
| Stu_Name | varchar(10) | YES | | | |
| Stu_Class | varchar(10) | YES | | | |
+-----------+-------------+------+-----+---------+-------+
|
Alter column Not Null Query
ALTER TABLE Stu_Table MODIFY Stu_Id int(3)not null
|
Describe Stu_Table
+-----------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| Stu_Id | int(3) | No | | | |
| Stu_Name | varchar(10) | YES | | | |
| Stu_Class | varchar(10) | YES | | | |
+-----------+--------------+------+-----+---------+-------+
|
|
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