1.inner join ,left join 与 right join (from 百度知道) 例表aaid adate1 a12 a23 a3表bbid bdate1 b12 b24 b4 (1)两个表a,b相连接,要取出id相同的字段 select * from a inner join b on a.aid = b.bid 此时的取出的是:1 a1 b12 a2 b2 (2)left join 指:select * from a left jo
convert(varchar(10),字段名,转换格式)sybase下convert函数第三个参数(时间格式)比如:1.select user_id,convert(varchar(10),dayts,11) as dates from tb_user (sybase下及sql server下语句) 2.select to_char(sysdate,'yy/mm/dd') as d from dual (oracle下语句) 转换格式:0或100 month dd yyyy hh: