What's the complete and proper syntax for that SQL Situation statement?

The complete syntax is dependent around the database engine you are dealing with:

For SQL Server:

  CASE case-expression
      WHEN when-expression-1 THEN value-1
    [ WHEN when-expression-n THEN value-n ... ]
[ ELSE else-value ]
  END

or:

  CASE
      WHEN boolean-when-expression-1 THEN value-1
    [ WHEN boolean-when-expression-n THEN value-n ... ]
[ ELSE else-value ]
  END

expressions, etc:

case-expression    - something that produces a value
when-expression-x  - something that is compared against the case-expression
value-1            - the result of the CASE statement if:
                         the when-expression == case-expression
                      OR the boolean-when-expression == TRUE
boolean-when-exp.. - something that produces a TRUE/FALSE answer

Link: http://msdn.microsoft.com/en-us/library/ms181765.aspx

Also observe that the ordering from the WHEN claims is essential. It is simple to write multiple WHEN clauses that overlap, and the first that suits can be used.

Note: If no ELSE clause is specified, with no matching WHEN-condition is located, the need for the Situation expression is going to be NULL.

Listed here are the good examples in the PostgreSQL paperwork (Postgres follows the conventional here):

SELECT a,
CASE WHEN a=1 THEN 'one'
WHEN a=2 THEN 'two'
ELSE 'other'
END
FROM test;

or

SELECT a,
CASE a WHEN 1 THEN 'one'
WHEN 2 THEN 'two'
ELSE 'other'
END
FROM test;

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