I'm working on some legacy code/database, and need to add a field to the database which will record a sequence number related to that column.
LIKE Example table data (current):
ID Q.No. Session File No
1 1010 6 1
2 556 6 2
3 598 7 1
4 789 7 2
5 756 8 1
I think you are asking how to add a column to a table that already exists. If this is correct, then you must use the ALTER TABLE command.
ALTER TABLE table ADD COLUMN column_name column_definition;
In your case, let us assume that your table is named table1 and your sequence numbers are basic integers that are small in size. One might use the following command:
ALTER TABLE table1
ADD COLUMN sequence INT;
Once you create your column, you can use an UPDATE query to add sequence numbers if the value is based in a simple function of other values, or you can use a series of UPDATES to handle records individually.
Because I am not an SQL expert, I tend to keep my SQL simple, and I do most of my processing in PHP. I would write a PHP script to assign sequence numbers to each table row, and then send an UPDATE query handling just that row and repeat until the table is filled.