Write a delete trigger

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Write a delete trigger
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Thursdays work

• If you have not already done so
• In your own schema, run the SetupTable.sql query
  from the student distrib directory.
• Write a trigger to prevent the user from deleting
  students from stages 1 to 3 of DT228.
• Write a trigger to warn the user of what they are
  doing if they delete students from ANY stage.
• Test your trigger