sql语句中的（＋）＝问题

[会子]

SELECT DWGDZCQKB.ND,DQB.DQMC,GDZCLBB_1.ZCLBMC_1,'-' AS ZCLBMC_2,'-' AS ZCLBMC_3,SUM (DWGDZCQKB.SL) AS SSL,SUM (DWGDZCQKB.JE) AS SJE FROM DWGDZCQKB,DQB,GDZCLBB_1 WHERE GDZCLBB_1.ZCLBBM_1 (+) = DWGDZCQKB.ZCLBBM_1
中的(+)=是什么意思？

[yeahnope]

不清楚,没有看到过这个东西.

[bzszp]

外连接
例子：
SQL> select * from a1;

BBB
----------
101
102
103
104
105

SQL> select * from a2;

BBB CCC
---------- --------------------
101
102
105

SQL> select * from a1,a2 where a1.bbb(+)=a2.bbb;

BBB BBB CCC
---------- ---------- --------------------
101 101
102 102
105 105

SQL> select * from a1,a2 where a1.bbb=a2.bbb(+);

BBB BBB CCC
---------- ---------- --------------------
101 101
102 102
103
104
105 105

SQL>

[bzszp]

外连接
例子：
SQL> select * from a1;

BBB
----------
101
102
103
104
105

SQL> select * from a2;

BBB CCC
---------- --------------------
101
102
105

SQL> select * from a1,a2 where a1.bbb(+)=a2.bbb;

BBB BBB CCC
---------- ---------- --------------------
101 101
102 102
105 105

SQL> select * from a1,a2 where a1.bbb=a2.bbb(+);

BBB BBB CCC
---------- ---------- --------------------
101 101
102 102
103
104
105 105

SQL>

[beckhambobo]

select * from a,b where a.id=b.id(+) --相当于 select * from a left join b on a.id=b.id;

select * from a,b where a.id(+)=b.id --相当于 select * from a right join b on a.id=b.id;