Change database column name and its type without losing data

Question

I want to change name and type of column from BIT(1) to INT(1) .

I am using MySQL Workbench.

I tried this:

ALTER TABLE table_name ADD new_column_name INT(1)

update table_name
set new_column_name = convert(INT(1), old_column_name)

ALTER TABLE table_name DROP COLUMN old_column_name

But I am getting this error

You have an error in your SQL syntax; check the manual that corresponds to your
MySQL server version for the right syntax to use near 'INT(1), old_column_name)'

Answer 1

ALTER TABLE table_name ADD new_column INT(1);

update table_name
  set new_column = case when old_column then 1 else 0 end;

ALTER TABLE table_name DROP COLUMN old_column;

or simply use:

ALTER TABLE table_name MODIFY COLUMN old_column int;

Answer 2

ALTER TABLE table_name CHANGE old_column_name new_col_name varchar(20) not null; 

I put varchar as an examaple. you can change to any data type you like. You can also add constraints after that.

Answer 3

Try something Like this.

ALTER TABLE table_name ADD new_column_name INT

update table_name
set new_column_name = convert(int,convert(varchar(1), old_column_name))

Answer 4

INT(1) doesn't seem to be a valid type for conversion.

Furthermore, the right syntax is CONVERT(<element>, <type>) .

You can find more in detail here .

Answer 5

ALTER TABLE table_name ALTER COLUMN creation_date TYPE timestamp USING creation_date::timestamp;

尝试这个