Question

在存储过程中，我想只在满足特定条件时才在查询中包含AND子句。

INSERT INTO #firstResults   
 SELECT x, y, z  FROM ep  
 WHERE ep.proposedBy = @Id  
 AND ep.pId IN ( SELECT DISTINCT pId FROM #tempProj)

只有当#tempProj不为空时，'AND'子句才会加入实现这一目标最优雅的方式是什么？

我在sql server 2008上由于这将在proc上重复多次，我希望避免分支IF语句。

Answer 1

试试这个......

AND (ep.pId IN (SELECT DISTINCT pId FROM #tempProj) 
                OR (SELECT COUNT(*) FROM #tempProj) = 0))

Answer 2

IF EXISTS (SELECT * FROM #tempProj)
 BEGIN
    INSERT INTO #firstResults   
    SELECT x, y, z  FROM ep  
    WHERE ep.proposedBy = @Id  
    AND ep.pId IN ( SELECT DISTINCT pId FROM #tempProj)
 END
ELSE
  BEGIN
    INSERT INTO #firstResults   
    SELECT x, y, z  FROM ep  
    WHERE ep.proposedBy = @Id 
  END

Answer 3

IF EXISTS (SELECT TOP 1 NULL FROM #tempProj)
BEGIN
INSERT INTO #firstResults   
 SELECT x, y, z  FROM ep  
 WHERE ep.proposedBy = @Id  
 AND ep.pId IN ( SELECT DISTINCT pId FROM #tempProj)
END
ELSE
BEGIN
 INSERT INTO #firstResults   
 SELECT x, y, z  FROM ep  
 WHERE ep.proposedBy = @Id  
END

动态AND子句

3 个答案: