Question

我有以下代码：

-- First Table:  
UPDATE     [H$Agency Header]
SET        [Booking Rating] = '1' --!!!!! CONDTION HERE !!!!!
FROM       [H$Agency Header] AH
INNER JOIN #RatingLines   RL1
ON         RL1.[B_KEY] = AH.[Reservation No_]
WHERE      RL1.[RTD_COMMENT] <> ''-- If the Booking have a comment inDB2
AND        [Booking Rating] = '0'    -- Get only Booking without Comments

如您所见，我将预订评级设置为1如果内部联接在两个表[H $ Agency Header]和#RatingLines中找到了公共行。现在我想说如果你没有找到它将它设置为＆＃39; 0＆＃39;。我可以在SET命令旁边放一个条件吗？如何？

Answer 1

假设上述查询已解析，那么您可以使用LEFT JOIN和CASE执行所需操作。这需要将注释的条件从where移动到on子句：

UPDATE AH
    SET [Booking Rating] = (CASE WHEN RLI.B_KEY IS NULL THEN '0' ELSE '1' END)
    FROM [H$Agency Header] AH LEFT JOIN
         #RatingLines RL1
         ON RL1.[B_KEY] = AH.[Reservation No_] AND
            RL1.[RTD_COMMENT] <> ''-- If the Booking have a comment inDB2
    WHERE AH.[Booking Rating] = '0'    -- Get only Booking without Comments

注意：如果[Booking Rating]是整数，则不应将0和1放在单引号中。尽管它有效，但将数字列设置为字符串值会产生误导。

Answer 2

你可以写成：

-- First Table:  
UPDATE     [H$Agency Header]
SET        [Booking Rating] = 
(case when RL1.[B_KEY] is null then '0' -- no match found
else '1'
end )
FROM       [H$Agency Header] AH
left  JOIN RatingLines   RL1 -- change join to Left
ON         RL1.[B_KEY] = AH.[Reservation No_] and  RL1.[RTD_COMMENT] <> ''
--WHERE      RL1.[RTD_COMMENT] <> ''-- If the Booking have a comment inDB2
--AND        [Booking Rating] = '0'

DEMO

根据条件Sql server更新了表？

2 个答案: