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Databases Querying Relational Databases Database Keys Foreign Keys

Noah Fields
Noah Fields
13,985 Points
Posted by Noah Fields
Noah Fields
13,985 Points

What happens when you do a Transaction with an error in it?

Let's say that I created a Transaction on a database with primary and foreign keys, and the Transaction inserted many rows - five, ten, or hundreds - of which some, but not all, had errors. For instance, some of the additions had primary key values that were already taken, or a foreign key referencing a primary key that didn't exist. When uploading all the changes specified in the Transaction, would it add the values that were correct and send errors for the incorrect ones? Would none of the changes take place until the errors were corrected? Or would something else occur?

2 Answers

Ari Misha
Ari Misha
19,323 Points
Ari Misha
Ari Misha
19,323 Points

Hiya Noah! Query wont happen at all. And If a TRANSACTION is successful, all of the data modifications made during the TRANSACTION are committed and become a permanent part of the database. If a TRANSACTION encounters errors and must be canceled or rolled back, then all of the data modifications are erased.

In your script file, you've to put "BEGIN", short for Begin Transaction, to let SQL server know that the following query needs to be executed in TRANSACTION mode. And followed by "COMMIT", to commit and finalize all your changes if everything happens successfully.

I hope it helped. (:

Teacher Russell
Teacher Russell
16,873 Points
Teacher Russell
Teacher Russell
16,873 Points

I just wanted to add that this topic is covered in the previous course, for anyone else who comes along and reads this. https://teamtreehouse.com/library/modifying-data-with-sql