Question

I’m using Oracle 10g. I want to append # to all values in ‘sal’ column. To acomplish this first I’m trying to change data type of ‘sal’ column from numeric to varchar but getting following error

What am I doing wrong ?

Answer 1

You should use modify keyword instead of your second alter .

alter table
   emp
modify
(
   sal    varchar2(10)
);

When modifying a tables column datatype , you need to use modify keyword.

Of course, you must deal with existing column data. When modifying a tables column datatype you may want to export the rows, redefine the table and then re-import you data.

In this you would need to follow these steps to alter a column data type:

1. Create the new column at the end of the table.
2. Run an update to populate the new table column
3. Drop the old table column
4. Re-name the new column to the original column name