问题如下:
SELECT *
FROM table1 a, table2 b,
WHERE a.1 = b.1
AND a.2 = b.2
AND a.3 = b.3
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初始 a表里有数据 b表里是空的 想用a的那三个字段联合起来 join b 的那三个字段
方法1:
select * from
table1 left outer join table2
on a.1=b.1 and a.2=b.2 and a.3=b.3
方法2:
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SELECT a.*
FROM table1 a, table2 b,
WHERE a.1 = b.1(+)
AND a.2 = b.2(+)
AND a.3 = b.3(+)
FROM table1 a, table2 b,
WHERE a.1 = b.1(+)
AND a.2 = b.2(+)
AND a.3 = b.3(+)
方法3:
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a.1||a.2||a.3做主键
b也同样处理,然后再外连接
b也同样处理,然后再外连接
SELECT a.*
FROM (select a.1||a.2||a.3 al from table1) a, (select b.1||b.2||b.3 bl from table2) b,
WHERE a.al = b.bl(+)
FROM (select a.1||a.2||a.3 al from table1) a, (select b.1||b.2||b.3 bl from table2) b,
WHERE a.al = b.bl(+)