Approaches to using Literal Values(UPDATE DELETE statements)

Lesson 6	Approaches to using literal values
Objective	Describe approaches using literal values in your UPDATE and DELETE statements.

Approaches to using Literal Values(UPDATE DELETE statements)

When issuing UPDATE and DELETE statements, you will want to use varying degrees of caution, depending on each individual circumstance.

A cautious approach

If you are not sure how many rows your UPDATE or DELETE statement will impact, you can issue a SELECT statement first, using the same criteria. This will show you how many rows will be affected when you run your query. Your select statement would look like this:

SELECT COUNT(*)
FROM Employees
WHERE EmployeeID = 101

An aggressive approach

A more aggressive approach would be to first issue the UPDATE or DELETE statement, then check the value of the SQL Server global variable,

 @@ROWCOUNT.

This is aggressive because the rows will already have been updated by the time the @@ROWCOUNT variable is updated. If more records were impacted than you expected, you have to figure out how to revise them back to their original values.

A medium approach

An approach between these two would be to wrap your statement within a transaction and roll it back if @@ROWCOUNT is something other than what you expect.
In the next lesson, you will learn about using punctuation with your statements.