mysql數據庫—表的查詢排序操作大全

表的查詢操作

　　select * from 表  *效率低 　　select * from 表 where id > 1
　　select nid,name,gender as gg from 表 where id > 1　　　　as相當於取別名，別名為gg 　　select count(id) from userinfo5; 查詢表內有多少條數據 　　select * from tb12; select id,name from tb12; select id,name from tb12 where id > 10 or name ='xxx'; select id,name as cname from tb12 where id > 10 or name ='xxx'; select name,age,11 from tb12; 多加了一列11 其他： select * from tb12 where id != 1
    select * from tb12 where id in (1,5,12); select * from tb12 where id not in (1,5,12); select * from tb12 where id in (select id from tb11) select * from tb12 where id between 5 and 12; 閉區間 通配符： select * from tb12 where name like "a%" 以a開頭的所有（多個字符） select * from tb12 where name like "a_" 以a開頭的所有（一個字符） 分頁： select * from tb12 limit 10; select * from tb12 limit 0,10; 0開始位置行，10查看的行數 select * from tb12 limit 10,10; select * from tb12 limit 20,10; select * from tb12 limit 10 offset 20; 20開始位置行，10查看的行數 排序： select * from tb12 order by id desc; 大到小 select * from tb12 order by id asc; 小到大 select * from tb12 order by age desc,id desc; 按優先級安序排列 取后10條數據 select * from tb12 order by id desc limit 10; 分組： select count(id),part_id from userinfo5 group by part_id; 統計數量 select max(id),part_id from userinfo5 group by part_id; part_id重合時，id取max select nin(id),part_id from userinfo5 group by part_id; 聚合函數（去除重復） count
     max
     min
     sum
     avg 平均值 **** 如果對於聚合函數結果進行二次篩選時？必須使用having ****
     select count(id),part_id from userinfo5 group by part_id having count(id) > 1; select count(id),part_id from userinfo5 where id > 0 group by part_id having count(id) > 1; 連表操作： select * from userinfo5,department5 where userinfo5.part_id = department5.id select * from userinfo5 left join department5 on userinfo5.part_id = department5.id # 左連接：userinfo5右邊允許有空 select * from userinfo5 right join department5 on userinfo5.part_id = department5.id # 右連接：department5左邊允許有空 select * from userinfo5 inner join department5 on userinfo5.part_id = department5.id # 內連接：不會出現null select * from userinfo5 full join department5 on userinfo5.part_id = department5.id # 完全連接：左右都可能出現null g、組合（上下連表） 組合，自動處理重合 select nickname from A union select name from B 組合，不處理重合 select nickname from A union all select name from B