Update Queries are useful when you need to add, change or delete data in one or more records across one or more tables. In other words, an Update Query searches your table for one piece of data then adds to it, changes it or deletes it based on your criteria specifications.
Essentially, you can use an update query to change all the data in a set of records.
Because there is no Undo when working with any Action Query, including an Update Query, it’s always a good idea to first create a Select Query to be sure the query is pulling the appropriate records before you make any permanent updates because any Select Query can be converted to an Action Query.
Create a Select Query that contains the criteria for the records you want to update
Run the Query to be sure you’re pulling the correct records
Switch to Design view
Click the Update command in the Query Type group on the Design tab
Figure 51. Update To Row
5. Enter text or an expression in the update row of the field you want to update
6. Click the Run command in the Results group on the Design tab
7. Click Yes