带条件语句的SQL INSERT IF then then

Question

我想将一个表中的值合并到另一个表中。其中一个值是一个条件值，但它看起来像我没有正确得到语法。最初，我使用了IF-THEN-ELSE语句，但建议使用CASE语句。

这里的要点是失败的语法：如果我不落实的情况

CREATE PROCEDURE EmployeeMerge 
AS 
BEGIN 
    SET NOCOUNT ON; 
    MERGE INTO Employee AS t1 
    USING 
     (SELECT 
       EmployeeName, 
       Zip, 
       UpdateDate 
     FROM table2) AS t2 
     ON (t1.EmployeeID = t2.EmployeeID) 
    WHEN MATCHED AND t2.UpdatedDate > t1.UpdatedDate THEN 
     UPDATE 
     SET 
      t1.EmployeeName = s.EmployeeName, 
      t1.Zip = 
       (CASE 
        WHEN t2.ZipExt IS NULL OR t2.ZipExt = '' THEN t2.Zip 
        ELSE (t2.Zip + '-' + t2.ZipExt) 
       END), 
      t1.UpdatedDate = t2.UpdateDate 
    WHEN NOT MATCHED THEN 
     INSERT (EmployeeName, 
      Zip, 
      ModDate) 
     VALUES 
      (t2.Name, 
      (CASE 
       WHEN t2.ZipExt IS NULL OR t2.ZipExt = '' THEN t2.Zip 
       ELSE (t2.Zip + '-' + t2.Zip_Ext) 
      END), 
      t2.UpdatedDate) 
    OUTPUT 
     deleted.*, 
     $action, 
     inserted.* 
END; **-- A MERGE statement must be terminated by a semi-colon (;)** 
GO 

这MERGE语句工作得很好，即简单地设置t1.Zip = t2.Zip，但当然，这是避免t2.ZipExt字段。

Answer 1

MERGE语句必须用分号（;）结束

您还没有用分号结束的MERGE。您已终止BEGIN-END。移动分号。

Answer 2

我从来没有真正关心合并命令。有时候我可以看到使用它，但大多数情况下，它比我喜欢我的SQL更复杂。

UPDATE e 
SET  e.EmployeeName=t1.EmployeeName 
    , e.Zip=CASE 
       WHEN t1.ZipExt IS NULL OR t1.ZipExt = '' THEN t1.Zip 
       ELSE (t1.Zip + '-' + t1.ZipExt) 
      END 
    , e.UpdatedDate=t1.UpdatedDate 
FROM Employee e 
INNER JOIN Table t1 ON e.EmployeeID = t1.EmployeeID 
WHERE t1.UpdatedDate > e.UpdatedDate 

INSERT INTO Employee (EmployeeName,Zip,UpdatedDate) 
    SELECT 
      t1.EmployeeName 
     , t1.Zip=CASE 
       WHEN t1.ZipExt IS NULL OR t1.ZipExt = '' THEN t1.Zip 
       ELSE (t1.Zip + '-' + t1.ZipExt) 
      END 
     , t1.UpdatedDate 
    FROM Table t1 
    LEFT JOIN Employee e ON e.EmployeeID = t1.EmployeeID 
    WHERE e.EmployeeID IS NULL