SQL alter table
ALTER TABLE statement is used to add, delete, or modify columns in an existing table.To Add a column
ALTER TABLE table_name ADD column_name datatype ;
ALTER TABLE table-name add(column-name1 datatype1, column-name2 datatype2, column-name3 datatype3);
To delete a column
ALTER TABLE table_name DROP COLUMN column_name ;
Must Read:
some database systems don't allow deleting a column.
To change the data type of a column
SQL Server / MS Access:
ALTER TABLE table_name ALTER COLUMN column_name datatype;
My SQL / Oracle:
ALTER TABLE table_name MODIFY column_name datatype;
To Rename a column
Using alter command you can rename an existing column. Following is the Syntax,
alter table table-name rename old-column-name to column-name;
Here is an Example for this,
alter table Student rename address to Location;
The above command will rename address column to Location.