Exercise: Delete adult and betting sites, then roll back

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The answer to the exercise will be included and explained if you attend the Wise Owl course listed below!

Category ==> SQL  (115 exercises)
Topic ==> Transactions  (4 exercises)
Level ==> Average difficulty
Course ==> Advanced SQL
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 the world's leading websites.

This database contains a table called Data_at_14_Jan_2010, which contains the source data for the other tables:

SQL exercise - Transactions (image 1)

We're going to remove all BETTING and ADULT sites, such as the one shown selected

Write a query which:

  • Begins a transaction
  • Within this transaction, deletes all rows from the above table where the Category column is Betting or Adult
  • Stores how many rows are left in the table in an integer variable
  • Rolls back the transaction
  • Stores how many rows are in the table after this roll back (in a second integer variable)
  • Displays the final figures

Your query should display output similar to this, when run:

SQL exercise - Transactions (image 2)

The transaction (if not rolled back) would have deleted 9 sites

Optionally, save this code as Delete sites then roll back.sql, then close it down.

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