I'm wishing I could do something like the following in SQl Server 2005 (which I know isnt valid) for my where clause. Sometimes @teamID (passed into a stored procedure) will be the value of an existing teamID, otherwise it will always be zero and I want all rows from the Team table.
I researched using Case and the operator needs to come before or after the entire statement which prevents me from having a different operator based on the value of @teamid. Any suggestions other than duplicating my select statements.
declare @teamid int
set @teamid = 0
Select Team.teamID From Team
case @teamid
when 0 then
WHERE Team.teamID > 0
else
WHERE Team.teamID = @teamid
end
The SQL IN OperatorThe IN operator allows you to specify multiple values in a WHERE clause. The IN operator is a shorthand for multiple OR conditions.
In a SQL statement, the WHERE clause specifies criteria that field values must meet for the records that contain the values to be included in the query results.
Ternary Operator in SQL also be termed as Conditional Operator can be defined as a unique decision-making operator found in many programming languages. Case Expression can be expanded as a generalization of Ternary Operator.
You should use the WHERE clause to filter the records and fetching only the necessary records. The WHERE clause is not only used in the SELECT statement, but it is also used in the UPDATE, DELETE statement, etc., which we would examine in the subsequent chapters.
You can do that without a case:
SELECT Team.teamID
FROM Team
WHERE (@teamid = 0 AND Team.teamID > 0)
OR (@teamid <> 0 AND Team.teamID = @teamid)
Without using dynamic SQL, the most performant option is:
IF @teamid = 0
BEGIN
SELECT t.teamid
FROM TEAM t
WHERE t.teamid > 0
END
ELSE
BEGIN
SELECT t.teamid
FROM TEAM t
WHERE t.teamid = @teamid
END
Using Dynamic SQL:
DECLARE @SQL NVARCHAR(4000)
SET @SQL = 'SELECT t.teamid
FROM TEAM t
WHERE 1 = 1 '
SET @SQL = @SQL + CASE @teamid
WHEN 0 THEN ' AND t.teamid > 0 '
ELSE ' AND t.teamid = @teamid '
END
BEGIN
EXEC sp_EXECUTESQL @SQL N'@teamid INT', @teamid
END
Beware that sp_EXECUTESQL
caches the query plan, while EXEC will not. Read this: http://www.sommarskog.se/dynamic_sql.html
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