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select usercode from table1 where usercode not in (select Usercode from table2) 这样的sQL 语句执行起来的效率非常低 有没有好的实现方法
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hdkkk 2003-08-26
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select usercode from t1 where not exists (select 'X' from t2 where t1.usercode=t2.usercode)
hdkkk 2003-08-26
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select usercode from table1 minus (select Usercode from table2)
hh23_ 2003-08-26
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select t1.usercode from table1 t1,table2 t2 where t1.usercode<>t2.usercode
hdkkk 2003-08-26
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我的错了,请勿略
jiezhi 2003-08-26
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select a.usercode from table1 a,table2 b where
a.usercode<>b.usercode
a.usercode<>b.usercode
armu80830 2003-08-26
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select usercode from table1
minus
select Usercode from table2
minus
select Usercode from table2
hdkkk 2003-08-26
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select usercode from table1 where usercode not exists (select Usercode from table2)
select t1.usercode from table1 t1,table2 t2 where t1.usercode<>t2.usercode
select t1.usercode from table1 t1,table2 t2 where t1.usercode<>t2.usercode
enhydraboy 2003-08-26
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select table1.usercode from table1,table2 where
table1.usercode = table2.usercode(+) and table2.username is null
table1.usercode = table2.usercode(+) and table2.username is null
yaotiebing 2003-08-26
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minus 比 not in 的效率高吗？？
