How to change column datatype in SQL database without losing data

Question

I have SQL Server database and I just realized that I can change the type of one of the columns from int to bool.

How can I do that withou

Answer 1

if you use T-SQL(MSSQL); you should try this script:

ALTER TABLE [Employee] ALTER COLUMN [Salary] NUMERIC(22,5)

if you use MySQL; you should try this script:

ALTER TABLE [Employee] MODIFY COLUMN [Salary] NUMERIC(22,5)

if you use Oracle; you should try this script:

ALTER TABLE [Employee] MODIFY [Salary] NUMERIC(22,5)