OR OR IN V2K

Do you ever get tired of trying to evaluate an expression for multiple
values? Minimize your workload by taking advantage of the IN clause 
within
SQL statements. Assume that you are writing a simple 
statement/procedure
to determine whether you do business in a particular state. Follow the
simple scenario below to see how the IN clause can ease your pain.

Given a scenario in which you do business only in the states of 
Georgia,
Kentucky, Tennessee, Florida, and Virginia, evaluate the following.

DECLARE @State CHAR(2)
SET @State = 'CO'
IF @State = 'GA' OR @State = 'KY' OR @State = 'TN'
OR @State = 'FL' OR @State = 'VA'
  PRINT 'We do business in the state of ' + @State
ELSE
  PRINT 'We do NOT do business in the state
of ' + @State

The long evaluation of the @State variable can prove cumbersome to type
and to read. Consider using the IN clause in place of multiple ORs.

SET @State = 'KY'
IF @State IN ('GA','KY','TN','FL','VA')
  PRINT 'We do business in the state of ' + @State
ELSE
  PRINT 'We do NOT do business in the state of ' + @State

Another option is to create a ValidState table and select the valid
state values via a query to avoid hard coding within your application.

SET @State = 'FL'
IF @State IN (SELECT State FROM ValidState)
  PRINT 'We do business in the state of ' + @State
ELSE
  PRINT 'We do NOT do business in the state of ' + @State

In the preceding example, the IN clause behaves like multiple ORs. The
IN clause is much easier to type and read, however, and is useful 
within
queries.

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