Alter PostgreSQL column from integer to decimal

Thanks to a last minute client request a integer field in our database now needs to be a decimal, to two points.A value of 23 should become 23.00.

Is there a nice way I can convert the table and cast the data across?

I'll freely admit, I haven't done anything like this with PostgreSQL before so please be gentle with me.

Something like this should work:

alter table t alter column c type decimal(10,2);

Edit:

As @Oli stated in the comments; the first number is the entire length of the number (excluding the point) so the maxval for (10,2) would be 99999999.99

alter table table_name alter column columname type decimal(16,2);

for converting data type from int to decimal. with precession after decimal point 2 values it will come for example 10.285 then it will be 10.23.or in decimal place we can use numeric also it will work.