rspec/rules/S1862/tsql/rule.adoc

A ``++CASE++`` and a chain of ``++IF++``/``++ELSE IF++`` statements is evaluated from top to bottom. At most, only one branch will be executed: the first one with a condition that evaluates to ``++true++``.


Therefore, duplicating a condition automatically leads to dead code. Usually, this is due to a copy/paste error. At best, it's simply dead code and at worst, it's a bug that is likely to induce further bugs as the code is maintained, and obviously it could lead to unexpected behavior. 

== Noncompliant Code Example

----
IF @x = 1
  PRINT 'A'
ELSE IF @x = 2
  PRINT 'B'
ELSE IF @x = 1 -- Noncompliant
  PRINT 'C'

SELECT
  CASE col1
    WHEN 1 
      THEN 'A'
    WHEN 2 
      THEN 'B'
    WHEN 1  -- Noncompliant
      THEN 'C'
    ELSE 'D'
  END
FROM table1
----

== Compliant Solution

----
IF @x = 1
  PRINT 'A'
ELSE IF @x = 2
  PRINT 'B'
ELSE IF @x = 3
  PRINT 'C'

SELECT
  CASE col1
    WHEN 1 
      THEN 'A'
    WHEN 2 
      THEN 'B'
    WHEN 3 
      THEN 'C'
    ELSE 'D'
  END
FROM table1
----

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== Comments And Links
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