如何使用where子句从另一个表修改sql表？

Question

我想更新test1表格的一些行.ColumnCtest1中为零.

例如:

ColumnA是父节点.ColumnA + ColumnB是主键.

create table test(ColumnA int,  ColumnB int,  ColumnC int);
Insert Into test Values(1, 10,0);
Insert Into test Values(2, 11,0);
Insert Into test Values(3, 14,0);

create table test1(ColumnA int,  ColumnB int,  ColumnC int);
Insert Into test1 Values(1, 9,123);
Insert Into test1 Values(1, 10,0);
Insert Into test1 Values(2, 10,128);
Insert Into test1 Values(2, 11,0);
Insert Into test1 Values(3, 13,145);
Insert Into test1 Values(3, 14,0);

我想要的结果:

我不工作的代码:

update test1 a 
set a.ColumnC = b.ColumnC
from test1 as b where convert(nvarchar,b.ColumnA)+
convert (nvarchar,b.ColumnB)in(select
convert(nvarchar,c.ColumnA)+
convert (nvarchar,c.ColumnB)  ColumnC  
from test as c);
select * from test1

我怎样才能做到这一点？

Answer 1

试试这个 :

update a set a.ColumnC=b.ColumnC


from test1 a 
inner join test1 b
on b.ColumnA=a.ColumnA and b.ColumnC!=0
and a.ColumnC=0;


select * from test1;

SQL小提琴