2016-10-14 17:49发布
想查询table表中三个字段（field1,field2,field3）去重的记录个数?应该怎么写查询语句呢？
hash_field = HASH(field1,field2,field3)
最多设置5个标签!
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hash_field = HASH(field1,field2,field3)
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