Self-Join?

[rpaulson9991]

I am having in a little difficulty understanding how to us a self-join. I was told that this would be the solution but having a problem grasping the concept or just seeing how it would work.

What I have is a inventory database about my inventory of computers monitor routers switches etc. The problem that I am having is how to handle a warranty replacement. I have tag numbers for the equipment that is linked to a PO. Example: Cisco Router dies and SmartNet replaces the router and the serial number changes, but the tag number would stay the same. I would like to keep the original serial number and the date installed in case I was asked what happened to the equipment and would like to beable to search by tag numbers.

What would be the best solution?

I have 4 tables

tblReq

autoindexReg

req

po

reqdate

podate

parts ordered

etc

tblItems

autoindexItems

po

tag

device

manuf

serialnumber

partnumber

etc

tblLocation

autoindexLocation

tag

building

room

fname

lname

depart

etc

tblbuilding

indexBuildingNumbers

building

[comment]

What exactly is a "tag number"?

[rpaulson9991]

What exactly is a "tag number"?

It is a 5 digit sequential number we give to the equipment when we put it into inventory. For easier management.

[comment]

I am not still not sure I follow this fully. In any case, a self-join is created by defining a relationship between two occurrences of the same table, e.g.:

Items::Tag = Items 2::Tag

This would allow you to place a portal on a layout of Items showing records from Items 2. These would be all "sibling" items sharing the same tag number.

Of course, you can skip the self-join and simply find all items that have the tag number of the current record.