Write a query to modify the datatype of the column departmentId from VARCHAR(30) to INT in the table 'department'.Refer to the existing table DLL given below:

To modify the datatype of the column departmentId from VARCHAR(30) to INT in the table department, you would use an ALTER TABLE statement.

SQL Query

ALTER TABLE department
MODIFY COLUMN departmentId INT;

Explanation

1. ALTER TABLE department: This part of the query specifies that we are altering the structure of the table named 'department'.
2. MODIFY COLUMN departmentId INT: This indicates that we want to change the data type of the column departmentId to INT.

Important Consideration

Before executing this query, ensure that all existing values in the departmentId column can be converted to integers without any loss of data. If any values are not convertible, this operation will fail. It’s advisable to take a backup of the data or perform data validation prior to making this change.