Write a query to change the datatype of the column starttime to datetime in the table 'bookings' and make it as Not null column

To change the datatype of a column in SQL, you can use the ALTER TABLE command. Here's how you can change the datatype of the column 'starttime' to datetime and make it a NOT NULL column in the 'bookings' table:

Step 1: First, you need to ensure that all existing data in the 'starttime' column can be converted to datetime. If there are any values that can't be converted, you'll need to update or delete these rows.

Step 2: Once you're sure all data can be converted, you can change the datatype of the column. Here's the SQL command to do this:

ALTER TABLE bookings
ALTER COLUMN starttime TYPE datetime;

Step 3: After changing the datatype, you can set the column to NOT NULL. Here's the SQL command to do this:

ALTER TABLE bookings
ALTER COLUMN starttime SET NOT NULL;

Please note that these commands are for PostgreSQL. The exact syntax might vary depending on the SQL dialect you're using. For example, in MySQL, the command to change the datatype would be:

ALTER TABLE bookings
MODIFY COLUMN starttime datetime NOT NULL;

In both cases, you should replace 'datetime' with the exact datetime type that's appropriate for your data.