declare @tV varchar(10)
declare tCur cursur for select a from table
open tCur
fetch next from tCur into @tVs
while
begin
@res += @tV
fetch next from tCur into @tV
end
close tCur
insert into table set b=@res
如图所示为原表格结构。
使用: 1 as 'col_num','1' as 'col_char'
分别添加了1个数值列,一个字符列,即虚拟列。
selecttb_a.A1,
tb_a.A2,
tb_a.A3,
isnull(cnt,0) as tb_a.虚字段
from tb_a
left join (select A1, count(1) as cnt
from tb_b
group by A1
) as b on b.A1 = tb_a.A1
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