The better question is why do you have 4 copies of the same field in various tables?
Maybe i didnt organize my database the right way. I need to store information about around 300 building. I have plan to make tables.
1-buildding Info 2-Bulding Systems 3- Network 4- Services Calls
-# Building - # building -#Device -# building
-Name of the building - System Name -#Port -Date
- maintenance - cooling/heating -IP -description
- Remote access -# Building - Work done by
the only relation between each table is the # building. Should i do only 2 table ; Building Info and services calls?
More likely, you'll want to change the # Building fields, and call them Building ID instead. Add a new 'Building Num' field to the Building Info table, relate all the tables by Building ID, then on whatever layouts you have # Building now, change it to 'Building Info::Building Num'
One of the basics behind a relational db is to try and store information only once. If you have a meaningful field such as building number, you will run into issue like your current one where you have to change it everywhere. Instead, if you use a meaningless ID field, then all you have to do is change information once and through relationships, you can refer to that meaningful field from other tables.