Sometimes we need to change the data type of a column. To do this, we use the ALTER TABLE Modify Column command. For Oracle and MySQL, the SQL syntax for ALTER TABLE Modify Column is,
ALTER TABLE "table_name"
MODIFY "column 1" "New Data Type"
For SQL Server, the syntax is,
ALTER TABLE "table_name"
ALTER COLUMN "column 1" "New Data Type"
Let's look at the example. Assuming our starting point is the "customer" table created in the CREATE TABLEsection:
Table customer
| Column Name | Data Type |
| First_Name | char(50) |
| Last_Name | char(50) |
| Address | char(50) |
| City | char(50) |
| Country | char(25) |
| Birth_Date | date |
Our goal is to alter the data type of the "Address" column to char(100). To do this, we key in:
MySQL:
ALTER TABLE customer MODIFY Address char(100);
Oracle:
ALTER TABLE customer MODIFY Address char(100);
SQL Server:
ALTER TABLE customer ALTER COLUMN Address char(100);
Resulting table structure:
Table customer
| Column Name | Data Type |
| First_Name | char(50) |
| Last_Name | char(50) |
| Address | char(100) |
| City | char(50) |
| Country | char(25) |


7:08 AM
Deep Dey
0 comments:
Post a Comment