left join 或者用 (+) 运算符。select a....,b.... from ylbj_jkwd_tw a,ylbj_jkwd_hd b where a.id = b.id(+) 表示选择a表中的id等于b表中的id记录,不论b表中是否存在相应的id。 还可以写成 select a....,b.... from ylbj_jkwd_tw a,ylbj_jkwd_hd b where a.id(+) = b.id 则表示选择a表中的id等于b表中的id记录,不论a表中是否存在相应的id。
select * from ylbj_jkwd_tw t1,ylbj_jkwd_hd t2 where t1.CONN_ID(+)=t2.CONN_ID 以上为右连接 select * from ylbj_jkwd_tw t1,ylbj_jkwd_hd t2 where t1.CONN_ID=t2.CONN_ID(+) 以上为左连接
左连接 select t1.id,t1.WENTI,t1.IN_DATE from ylbj_jkwd_tw t1,ylbj_jkwd_hd t2 where t1.id(+)=t2.CONN_ID 右连接 select t1.id,t1.WENTI,t1.IN_DATE from ylbj_jkwd_tw t1,ylbj_jkwd_hd t2 where t1.id=t2.CONN_ID(+)
from ylbj_jkwd_tw a,ylbj_jkwd_hd b
where a.id = b.id(+)
表示选择a表中的id等于b表中的id记录,不论b表中是否存在相应的id。
还可以写成
select a....,b....
from ylbj_jkwd_tw a,ylbj_jkwd_hd b
where a.id(+) = b.id
则表示选择a表中的id等于b表中的id记录,不论a表中是否存在相应的id。
以上为右连接
select * from ylbj_jkwd_tw t1,ylbj_jkwd_hd t2 where t1.CONN_ID=t2.CONN_ID(+)
以上为左连接
select t1.id,t1.WENTI,t1.IN_DATE from ylbj_jkwd_tw t1,ylbj_jkwd_hd t2 where t1.id(+)=t2.CONN_ID
右连接
select t1.id,t1.WENTI,t1.IN_DATE from ylbj_jkwd_tw t1,ylbj_jkwd_hd t2 where t1.id=t2.CONN_ID(+)