mysql 操作记录

一些重要操作记录。

避免重复插入
INSERT INTO lhlh_emotion (word, freq, tag) 
SELECT ‘{emotion}‘, 100, ‘a‘ 
from DUAL 
where not exists(select word from lhlh_emotion where word=‘{emotion}‘);

原文：https://www.cnblogs.com/bingwork/p/9183268.html