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 it is a valid change.

you can change the property.

Tools --> Options --> Designers --> Table and Database designers --> Uncheck --> Prevent saving changes that required table re-creation.

Now you can easily change the column name without recreating the table or losing u r records.

Answer 2

ALTER TABLE tablename
ALTER COLUMN columnname columndatatype(size)

Note: if there is a size of columns, just write the size also.

Answer 3

Go to Tool-Option-designers-Table and Database designers and Uncheck Prevent saving option

Answer 4

I can modify the table field's datatype, with these following query: and also in the Oracle DB,

ALTER TABLE table_name
MODIFY column_name datatype;

Answer 5

Replace datatype without losing data

alter table tablename modify columnn  newdatatype(size);