Changing a field's data

[kernal]

I'm using the Peoplesoft Query Manager.

When a meeting pattern (i.e. days, times, etc.) is entered on a class then it is assigned a pattern number (some classes could have more than 1 meeting pattern). Example:

Class Pat_Nbr Days, etc.

1-1 1 Mon

2-1 1 Tues
2-1 2 Thurs

If a class's meeting pattern is deleted and another one is entered then class 2-1 would look like the following:

Class Pat_Nbr Days, etc.

1-1 1 Mon

2-1 2 Thurs
2-1 3 Fri

Is there a way in an expression to change the Pat_Nbr so a class always has Pat_Nbr 1 and then following numbers also change so:

Class Pat_Nbr Days, etc.

1-1 1 Mon

2-1 1 Thurs
2-1 2 Fri

Help is appreciated. Thanks