Question

i have three table

table t1;
Sid sValue
1   abc
2   bcd

table t2
Sid  Pid  Mid
1    a    9
2    a    10
3    b    9

table t3
Mid  MValue
9    ZZZZ
10   yyyy

i want to update table t1 and set t1.sVal="" where t2.Pid= a and t3.MValue= zzzz

how can i do this pls help me thanks in advance

i have tried it like

update t1 set sVal="" where Sid=(select Sid from t2 where Pid= a  and Mid=(select Mid from t3 where MVale= ZZZZ ))

but it doesnt work and thorw error like

An object or column name is missing or empty. For SELECT INTO statements, verify each column has a name. For other statements, look for empty alias names. Aliases defined as "" or [] are not allowed. Add a name or single space as the alias name.

Answer 1

The problem is that you are using double quotes instead of single quotes in your set statement.

定点数

不包括Val=”

但是,如果你想作更清洁的更新说明,则该守则应当这样做。

update t1 定点数
from t1
inner join t2 on t1.sid=t2.sid
inner join t3 on t2.Mid=t3.Mid
where t2.Pid= a  and t3.MVale= ZZZZ

Answer 2

为此:

update t1 SET t1.sVal =   
INNER JOIN t2
ON t1.sid = t2.sid
INNER JOIN t3
ON t2.mid = t3.mid
WHERE t2.Pid= a  and t3.MValue= zzzz

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