SQL Server 2008 - 根据行的相似分组的列更新列

Question

如果可能，我正在查找单个更新语句。

考虑：

rsvpgroup | personid | isVip | firstname | lastname | type 
------------------------------------------------------------------ 
1    100   1  bob   smith  leader 
1    101   0  john  doe  guest 
1    102   0  sara  jones  guest 
2    200   0  tom   ohara  leader 
2    201   0  jane  doe  guest 

我需要一个RSVP组中要更新isVIP为客人如果他们的“领头羊” isVip = 1

因此，在这种情况下排，2和3以上将被更新0到1行4个，5将保持不变

Answer 1

UPDATE a 
SET  a.isVip = 1 
FROM TableName a 
     INNER JOIN TableName b 
      ON a.rsvpgroup = b.rsvpgroup AND 
       b.[type] = 'leader' AND 
       b.isVip = 1 
WHERE a.[type] = 'guest' 

• SQLFiddle Demo
更新后声明

产量一直执行

╔═══════════╦══════════╦═══════╦═══════════╦══════════╦════════╗ 
║ RSVPGROUP ║ PERSONID ║ ISVIP ║ FIRSTNAME ║ LASTNAME ║ TYPE ║ 
╠═══════════╬══════════╬═══════╬═══════════╬══════════╬════════╣ 
║   1 ║  100 ║  1 ║ bob  ║ smith ║ leader ║ 
║   1 ║  101 ║  1 ║ john  ║ doe  ║ guest ║ 
║   1 ║  102 ║  1 ║ sara  ║ jones ║ guest ║ 
║   2 ║  200 ║  0 ║ tom  ║ ohara ║ leader ║ 
║   2 ║  201 ║  0 ║ jane  ║ doe  ║ guest ║ 
╚═══════════╩══════════╩═══════╩═══════════╩══════════╩════════╝ 

Answer 2

这里使用的窗口功能和CTE是一种方法：

with toupdate as (
     select t.*, 
      max(case when [type] = 'leader' then IsVIP end) over 
         (partition by RSVPgroup) as LeaderIsVIP 
     from t 
    ) 
update toupdate 
    set IsVIP = LeaderIsVIP 
    where IsVIP <> LeaderIsVIP;