举例
a(id,col),
1,a
2,a
b(id,col1)
1,a
select a.id,a.col from a,b where a.id = b.id
结果
1 a
select a.id,a.col from a,b where a.id = b.id(+)
结果
1 a
2 a
a(id,col),
1,a
2,a
b(id,col1)
1,a
select a.id,a.col from a,b where a.id = b.id
结果
1 a
select a.id,a.col from a,b where a.id = b.id(+)
结果
1 a
2 a
SELECT c.cust_id, c.company, s.amount
FROM customers c, sales s
WHERE c.cust_id = s.cust_id (+);
可写成92标准:
SELECT c.cust_id, c.company, s.amount
FROM customers c LEFT OUTER JOIN sales s
ON c.cust_id = s.cust_id (+);