ALTER TABLE by default adds new columns at the end of the table. Use the
AFTER directive to place it in a certain position within the table:
ALTER table table_name
Add column column_name57 integer AFTER column_name56
From mysql doc
To add a column at a specific position within a table row, use
col_name. The default is to add the column last. You can also use
MODIFYoperations to reorder columns within a table.
I googled for this for PostgreSQL but it seems to be impossible.