Triggers may be used to prevent changes to rows that have already been reconciled or should not be changed for other reasons.
- Triggers may also be used to prevent changes … to rows that have already been reconciled or … should not be changed for other reasons. … Here again I'm using the test database … and I've pasted some statements in from the … chapter 10 exercise files. … First thing I'm going to do is, … I'm going to drop this table widget sale … which we created in the last lesson … and you'll notice that it has a trigger in it … and when I drop that table, … the table is gone and the trigger is gone. … We're going to create the table again … and in this case, … I'm adding a reconciled flag … so it's got basically the same columns as the table … had before with the addition of this new column reconcile. … So I'm going to create that. … And you'll notice that our trigger is gone … and that's okay, … we're not going to need it, … I just wanted to point out that … at least in this implementation, … triggers are stored with the table. … That may not be true in every database system. … So I'm going to insert these three rows, …
This course was created by Bill Weinman. We are pleased to offer this training in our library.
- How databases are organized
- Selecting rows and columns
- Creating new tables
- Inserting and updating data
- Sorting and filtering
- Accessing related tables with JOIN
- Working with strings
- Understanding numeric types
- Using aggregate functions and transactions
- Automating data with triggers
- Creating views
- Using CRUD functions
Skill Level Beginner
2. SQL Overview
3. Fundamental Concepts
7. Dates and Times
Dates and times2m 6s
11. Views and Subselects
12. A Simple CRUD Application
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