Adding a column after another column within SQL
Assuming MySQL (EDIT: posted before the SQL variant was supplied):
ALTER TABLE myTable ADD myNewColumn VARCHAR(255) AFTER myOtherColumn
The AFTER keyword tells MySQL where to place the new column. You can also use FIRST to flag the new column as the first column in the table.
It depends on what database you are using. In MySQL, you would use the "ALTER TABLE" syntax. I don't remember exactly how, but it would go something like this if you wanted to add a column called 'newcol' that was a 200 character varchar:
ALTER TABLE example ADD newCol VARCHAR(200) AFTER otherCol;