初學mysql總結(2)

初學mysql總結(2)

今天繼續更新初學mysql，接下來下面都是關於必備的查找表的命令。使用表：student
1,查詢表全部字段數據：select * from student;

2,查詢某個字段的數據：select name from student ;

3,查詢多個字段的數據：select name ,kemu,score from student;

4,根據條件查詢（where）：select * from student where scZ喎?http://www.Bkjia.com/kf/ware/vc/" target="_blank" class="keylink">vcmUmZ3Q7ODA7PGJyIC8+DQo8aW1nIGFsdD0="這裡寫圖片描述" src="http://www.bkjia.com/uploads/allimg/160403/04123SO2-3.png" title="\" />
5,根據多個條件查詢（where …and ..):select * from student where kemu=’PE’ and score>80;

6,根據首字母為j的名字的學生查詢：select * from student where name like ‘j%’;

7,根據學生的分數進行排序(升序ASC,降序DESC)查詢(order by):select * from student order by score asc;

8,根據關鍵字（in）查詢：select * from student where id in (1,2,3);

9,查詢分數的區間(between and ):select * from student where score between 80 and 90;

10,查詢分數不重復的數據（distinct）：select distinct name ,score from student;

11,分組查詢（group by）: select * from student group by name;

12,限制查詢結果的數量（limit) :select * from student order by asc limit 5;

13,使用常用函數count（）查詢，好處：若查詢字段有null，不會查詢出來：
select count（*） from student；

14,使用常用函數sum()求總和 ：select sum(score) from student;

15,使用常用函數avg()求平均值：select avg(score) from student;

16,使用常用函數min()求最小值，max（）求最大值：
select max(score),min(score) from student;

今天暫時更新到這裡！