Question

I need to alter the data type of a column in one table of mine, but this table contains data my problem is that I can’t empty the table to do my purpose so I need to Alter the column data type without emptying the table.

What can I do ?

Answer 1

Your best choice here is to create a new table new_table with the appropriate columns.

Once created, insert into this table the values of the existing table table as you want them. Only then reintroduce constraints etc (if you do this before insert, you’ll penalize insert performance).

Once done, rename table to old_table and new_table to table.

Of course, you need to do this with your application offline.