SQL | Archived exercise | Set importance column according to no of places

This exercise is provided to allow potential course delegates to choose the correct Wise Owl Microsoft training course, and may not be reproduced in whole or in part in any format without the prior written consent of Wise Owl.

Software ==> SQL  (198 exercises)
Version ==> Any version of SQL Server
Topic ==> Archived  (70 exercises)
Level ==> Harder than average
Subject ==> SQL training
Before you can do this exercise, you'll need to download and unzip this file (if you have any problems doing this, click here for help).

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If you haven't already done so, run the stored procedure in the above folder to generate a database of training courses and delegates.

Add a new integer column called Importance to the tblPerson table:

SQL exercise - Transactions (image 1)

The new column

Write a query which begins a transaction, and then updates the value of the Importance column for each person to:

  • 10 if this person has attended 1 or less courses (ie if the number of rows in the tblDelegate table for this PersonId is less than or equal to 1)
  • 20 if this person has attended 2 to 4 courses; or
  • 30 otherwise

Extend this query so that it deletes all "unimportant" people (ie those whose importance is 10), and prints out a message saying how many rows have been deleted:

SQL exercise - Transactions (image 2)

You should see 274 people have been zapped

Finally, add a condition which:

  • commits the transaction if there are still at least 500 people left in the table; or
  • rolls it back otherwise

Optionally, save this query as How not to run a training company.sql, then close it down.

You can unzip this file to see the answers to this exercise, although please remember this is for your personal use only.
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