他们返回的行相同的计数,但我不知道,如果一个是事故等待发生,或一个是简单地“的首选方法”:这两个SQL语句是否相同?
SELECT duckbill.id, duckbill.pack_size, duckbill.description, duckbill.platypus_id, duckbill.department, duckbill.subdepartment, duckbill.unit_cost, duckbill.unit_list, duckbill.open_qty, duckbill.UPC_code, duckbill.UPC_pack_size, duckbill.crv_id, duckbill_platypuss.platypus_item
FROM duckbill
INNER JOIN duckbill_platypuss ON duckbill.platypus_id = duckbill_platypuss.platypus_id
SELECT duckbill.id, duckbill.pack_size, duckbill.description, duckbill.platypus_id, duckbill.department, duckbill.subdepartment, duckbill.unit_cost, duckbill.unit_list, duckbill.open_qty, duckbill.UPC_code, duckbill.UPC_pack_size, duckbill.crv_id, duckbill_platypuss.platypus_item
FROM duckbill, duckbill_platypuss
WHERE (duckbill.platypus_id = duckbill_platypuss.platypus_id)
他们应该是等价的,但我会建议使用ANSI语法('INNER JOIN')以提高可读性。 – NullUserException 2013-03-08 16:35:49
mysql解析器优化查询;所以从实际的角度来看也是一样的。 – palerdot 2013-03-08 16:37:00
我没有使用MySQL,我正在使用祖父的SQL – 2013-03-08 16:38:27