[英]Mysql using temporary
我的查询使用一个临时表,但我做错了,有人可以告诉我吗?
EXPLAIN SELECT DISTINCT t.city_id FROM (SELECT city_id FROM `geo__base` Where country = 'DE')as t
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE geo__base ref country country 8 const 43460 Using index condition; Using where; Using temporar...
谢谢大家
尝试这样的事情:
SELECT DISTINCT city_id FROM (SELECT city_id FROM geo_base WHERE country = 'DE') tmp;
或如上面的fancyPants所述,只需使用以下命令:
SELECT DISTINCT city_id FROM geo_base;
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