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Error Code : 1060 Duplicate column name 'xxx'有重复字段Error Code: 1248. Every derived table must have its own alias每个派生出来的表都必须有一个自己的别名select count(*) from (select * from list where name="xiao") as ...

查询的count()不计算重复条目SELECT count(distinct(t_feeling.id)) FROM t_feeling,t_friend where (feeling_user=t_friend.frnd_frnd or feeling_user=1) and t_friend.frnd_user=1查询结果不重复SELECT distinct *...

MyBatis往MySQL中插入一条记录后，需返回该条记录的自增主键值<insert id="addBlog" parameterType="Blog" keyProperty="id" useGeneratedKeys="true"> INSERT INTO t_blog VALUES(null,#{title},#{summary},now(),0,0,#{conten...

select Concat('&lt;a style=color:#4294E3; href=javascript:show(\'', id, '\') &gt;', id, '&lt;a &gt;') id1from t_hy