mysql數據庫CURD

時間 2019-11-13

標籤 mysql 數據庫 curd 欄目 MySQL 简体版

原文原文鏈接

mysql> create database if not exists mydb2 character set utf8;java

mysql> create table employee(mysql

-> id int,sql

-> name varchar(20),數據庫

-> sex varchar(20),express

-> birthday date,c#

-> entry_date date,oracle

-> job varchar(20),函數

-> salsay float(5,1),sqlserver

-> resume text);spa

Query OK, 0 rows affected (1.05 sec)

Insert

語法L

INSERT INTO table[(column[, column...])]

VALUES (value[,value...]);

l 插入的數據應與字段的數據類型相同。

l 數據的大小應在列的規定範圍內，例如：不能將一個長度爲80的字符串加入到長度爲40的列中。

l 在values中列出的數據位置必須與被加入的列的排列位置相對應。

l 字符和日期型數據應包含在單引號中。

l 插入空值，不指定或insert into table value(null)

l 注意：字符和日期要包含在單引號中。

mysql> insert into employee values(1,'java','male','1990-04-23','1990-05-08','pm

',5000.1,'hello');

Query OK, 1 row affected (0.11 sec)

mysql> insert into employee values(2,'mysql','male','1990-04-23','1990-05-08','pm',5000.1,'hello');

Query OK, 1 row affected(0.07 sec)

mysql> select *from employee;

+------+-------+------+------------+------------+------+--------+--------+

+------+-------+------+------------+------------+------+--------+--------+

| 1 | java | male | 1990-04-23| 1990-05-08 | pm | 5000.1 | hello |

| 2 | mysql | male | 1990-04-23 | 1990-05-08| pm | 5000.1 | hello |

+------+-------+------+------------+------------+------+--------+--------+

2 rows in set (0.00 sec)

--刪除

語法:

delete from tbl_name

[WHEREwhere_definition]

l 若是不使用where子句，將刪除表中全部數據。

l delete語句不能刪除某一列的值（可以使用update）

l 使用delete語句僅刪除記錄，不刪除表自己。如要刪除表，使用drop table語句。用於刪除數據量不大的數據

l 同insert和update同樣，從一個表中刪除記錄將引發其它表的參照完整性問題，在修改數據庫數據時，

l 刪除表中數據也可以使用TRUNCATE TABLE語句，它和delete有所不一樣。TRUNCATE(複製表結構->一次性刪除整表->自動恢復表結構，適合刪除數據量較大的數據，不能按條件進行刪除

l DELETE(逐行刪除記錄),按行刪除表的記錄，但會保留表，適合刪除數據量不大的數據，可按條件刪除

drop table:刪除表的自己

刪除記錄時，必定要留意表間的關聯關係

mysql> deletefrom employee where id=1;

Query OK, 1 row affected (0.10 sec)

mysql> select * from employee;

+------+-------+------+------------+------------+------+--------+--------+

+------+-------+------+------------+------------+------+--------+--------+

| 2 | mysql | male | 1990-04-23 | 1990-05-08| pm | 5000.1 | hello |

+------+-------+------+------------+------------+------+--------+--------+

1 row in set (0.00 sec)

--更新

l 使用 update語句修改表中數據。

語法:

UPDATE tbl_name

SETcol_name1=expr1[, col_name2=expr2 ...]

[WHEREwhere_definition]

l UPDATE語法能夠用新值更新原有錶行中的各列。

l SET子句指示要修改哪些列和要給予哪些值。

l WHERE子句指定應更新哪些行。如沒有WHERE子句，則更新全部的行

--先再插入幾條數據

mysql> insert into employee values(3,'c#','female','1991-04-23','1995-05-08','pm',6000.1,'how');

Query OK, 1 row affected (0.09 sec)

mysql> insert into employee values(4,'oracle','male','1950-04-23','1980-05-08','pm',1000.1,'are');

Query OK, 1 row affected (0.13 sec)

mysql> insert into employee values(5,'sqlserver','female','1970-04-23','1980-05-08','crm',4000.1,'you');

Query OK, 1 row affected (0.19 sec)

--將所人員的工資修改成5000

mysql> select * from employee;

+------+-----------+--------+------------+------------+------+--------+--------+

+------+-----------+--------+------------+------------+------+--------+--------+

| 2 | mysql | male | 1990-04-23| 1990-05-08 | pm | 5000.1 | hello |

| 3 | c# | female | 1991-04-23| 1995-05-08 | pm | 6000.1 | how |

| 4 | oracle | male | 1950-04-23| 1980-05-08 | pm | 1000.1 | are |

| 5 | sqlserver | female | 1970-04-23| 1980-05-08 | crm | 4000.1 | you |

+------+-----------+--------+------------+------------+------+--------+--------+

4 rows in set (0.00 sec)

mysql> update employee set salsay=5000;

Query OK, 4 rows affected (0.05 sec)

Rows matched: 4 Changed: 4 Warnings: 0

mysql> select * from employee;

+------+-----------+--------+------------+------------+------+--------+--------+

+------+-----------+--------+------------+------------+------+--------+--------+

| 2 | mysql | male | 1990-04-23| 1990-05-08 | pm | 5000.0 | hello |

| 3 | c# | female | 1991-04-23| 1995-05-08 | pm | 5000.0 | how |

| 4| oracle | male | 1950-04-23| 1980-05-08 | pm | 5000.0 | are |

| 5 | sqlserver | female | 1970-04-23| 1980-05-08 | crm | 5000.0 | you |

+------+-----------+--------+------------+------------+------+--------+--------+

4 rows in set (0.00 sec)

--修改id爲2的員工的工資爲8000

mysql> update employee set salsay=8000 where id=2;

Query OK, 1 row affected (0.05 sec)

Rows matched: 1 Changed: 1 Warnings: 0

mysql> select * from employee where id=2;

+------+-------+------+------------+------------+------+--------+--------+

+------+-------+------+------------+------------+------+--------+--------+

| 2 | mysql | male | 1990-04-23 | 1990-05-08| pm | 8000.0 | hello |

+------+-------+------+------------+------------+------+--------+--------+

1 row in set (0.00 sec)

=========================select=======================

mysql> create table student(

-> id int,

-> name varchar(20),

-> chinese float,

-> english float,

-> math float

-> );

Query OK, 0 rows affected (1.37 sec)

mysql>

mysql> insert into student(id,name,chinese,english,math) values(1,'張小明',89,78,90);

Query OK, 1 row affected (0.12 sec)

mysql> insert into student(id,name,chinese,english,math) values(2,'李進',67,98,56);

Query OK, 1 row affected (0.06 sec)

mysql> insert into student(id,name,chinese,english,math) values(3,'王五',87,78,77);

Query OK, 1 row affected (0.37 sec)

mysql> insert into student(id,name,chinese,english,math) values(4,'李一',88,98,90);

Query OK, 1 row affected (0.06 sec)

mysql> insert into student(id,name,chinese,english,math) values(5,'李來財',82,84,67);

Query OK, 1 row affected (0.04 sec)

mysql> insert into student(id,name,chinese,english,math) values(6,'張進寶',55,85,45);

Query OK, 1 row affected (0.09 sec)

mysql> insert into student(id,name,chinese,english,math) values(7,'黃蓉',75,65,30);

Query OK, 1 row affected (0.05 sec)

mysql> insert into student(id,name,chinese,english,math) values(8,'張一李',75,65,30);

Query OK, 1 row affected (0.25 sec)

mysql> insert into student(id,name,chinese,english,math) values(9,'何李',75,65,30);

Query OK, 1 row affected (0.06 sec)

mysql> insert into student(id,name,chinese,english,math) values(10,'單',75,65,30);

Query OK, 1 row affected (0.14 sec)

mysql> insert into student(id,name,chinese,english,math) values(11,'李',75,65,NULL);

Query OK, 1 row affected (0.11 sec)

mysql> insert into student(id,name,chinese,english,math) values(12,'jack',75,65,40);

Query OK, 1 row affected (0.08 sec)

mysql> insert into student(id,name,chinese,english,math)values(13,'marry',75,65,60);

Query OK, 1 row affected (0.12 sec)

mysql>

mysql> select * from student;

+------+-----------+---------+---------+------+

+------+-----------+---------+---------+------+

| 1 | 張小明 | 89 | 78 | 90 |

| 2 | 李進 | 67 | 98 | 56 |

| 3 | 王五 | 87 | 78 | 77 |

| 4 | 李一 | 88 | 98 | 90 |

| 5 | 李來財 | 82 | 84 | 67 |

| 6 | 張進寶 | 55 | 85 | 45 |

| 7 | 黃蓉 | 75 | 65 | 30 |

| 8 | 張一李 | 75 | 65 | 30 |

| 9 | 何李 | 75 | 65 | 30 |

| 10 | 單 | 75 | 65 | 30 |

| 11 | 李 | 75 | 65 | NULL |

| 12 | jack | 75 | 65 | 40 |

| 13 | marry | 75 | 65 | 60 |

+------+-----------+---------+---------+------+

13 rows in set (0.00 sec)

l 基本select語句

語法:

SELECT [DISTINCT] *|{column1,column2. column3..}

FROM table;

l Select指定查詢哪些列的數據。

l column指定列名。

l *號表明查詢全部列。

l From指定查詢哪張表。

l DISTINCT可選，指顯示結果時，是否剔除重複數據

查詢表中全部學生的信息

select * from student;

select id,name,match,chinese,english from student;

select name,id,match,english,chinese from student;

--查詢表中全部學生的姓名和英語成績

mysql> select name,english from student;

+-----------+---------+

| name | english |

+-----------+---------+

| 張小明 | 78 |

| 李進 | 98 |

| 王五 | 78 |

| 李一 | 98 |

| 李來財 | 84 |

| 張進寶 | 85 |

| 黃蓉 | 65 |

| 張一李 | 65 |

| 何李 | 65 |

| 單 | 65 |

| 李 | 65 |

| jack | 65 |

| marry | 65 |

+-----------+---------+

13 rows in set(0.00 sec)

--select distinct/*/列名 from表名

--使用distinct過濾重複數據

mysql> select distinct english from student;

+---------+

| english |

+---------+

| 78 |

| 98 |

| 84 |

| 85 |

| 65 |

+---------+

5 rows in set(0.00 sec)

-- select 表達式/對列名加別名 from 表名 NULL+X=NULL

語法:

SELECT *|{column1｜expression,column2｜expression，..}

FROM table;

--在全部學生數學分數上加10分的特長分

--SELECT column as別名 from 表名;使用as別名

mysql> select name,math+10 as 數學 from student;

+-----------+--------+

| name | 數學 |

+-----------+--------+

| 張小明 | 100 |

| 李進 | 66 |

| 王五 | 87 |

| 李一 | 100 |

| 李來財 | 77 |

| 張進寶 | 55 |

| 黃蓉 | 40 |

| 張一李 | 40 |

| 何李 | 40 |

| 單 | 40 |

| 李 | NULL |

| jack | 50 |

| marry | 70 |

+-----------+--------+

13 rows in set(0.00 sec)| marry | 75 |

+-----------+------------+

13 rows in set(0.00 sec)

--統計每一個學生的總分:

mysql> select name,math+english+chinese as 總分 from student;

+-----------+--------+

| name | 總分 |

+-----------+--------+

| 張小明 | 257 |

| 李進 | 221 |

| 王五 | 242 |

| 李一 | 276 |

| 李來財 | 233 |

| 張進寶 | 185 |

| 黃蓉 | 170 |

| 張一李 | 170 |

| 何李 | 170 |

| 單 | 170 |

| 李 | NULL |

| jack | 180 |

| marry | 200 |

+-----------+--------+

13 rows in set(0.00 sec)

--where子句，出如今from後面，where是按行篩選

比較運算符	> < <= >= = <>	大於、小於、大於(小於)等於、不等於
BETWEEN ...AND...	顯示在某一區間的值
IN(set)	顯示在in列表中的值，例：in(100,200)
LIKE ‘張pattern’	模糊查詢(重點)
IS NULL/IS NOT NULL	判斷是否爲空
邏輯運算符	and &&	多個條件同時成立
or \|\|	多個條件任一成立
not !	不成立，例：where not(salary>100);

Like語句中，%表明零個或多個任意字符，_表明一個字符，例first_name like ‘_a%’;

--查詢姓名爲張小明的記錄

mysql> select * from student where name='張小明';

+------+-----------+---------+---------+------+

+------+-----------+---------+---------+------+

| 1 | 張小明 | 89 | 78 | 90 |

+------+-----------+---------+---------+------+

1 row in set(0.00 sec)

--查詢英語大於90的學生

mysql> select * from student where english>90;

+------+--------+---------+---------+------+

+------+--------+---------+---------+------+

| 2 | 李進 | 67 | 98 | 56 |

| 4 | 李一 | 88 | 98 | 90 |

+------+--------+---------+---------+------+

2 rows in set(0.00 sec)

--查詢總分大於200的

mysql> select name, (chinese+english+math) as總分from student where (chinese+english+math)>200;

+-----------+--------+

| name | 總分 |

+-----------+--------+

| 張小明 | 257 |

| 李進 | 221 |

| 王五 | 242 |

| 李一 | 276 |

| 李來財 | 233 |

+-----------+--------+

5 rows in set(0.00 sec)

--查詢英語分數在80－90之間的同窗。

mysql> select *

-> from student

-> where english>=80 and english<=90;

+------+-----------+---------+---------+------+

+------+-----------+---------+---------+------+

| 5 | 李來財 | 82 | 84 | 67 |

| 6 | 張進寶 | 55 | 85 | 45 |

+------+-----------+---------+---------+------+

2 rows in set(0.00 sec)

或 (推薦下面的方式)

mysql> select *

-> from student

-> where english between 80 and 90;

+------+-----------+---------+---------+------+

+------+-----------+---------+---------+------+

| 5 | 李來財 | 82 | 84 | 67 |

| 6 | 張進寶 | 55 | 85 | 45 |

+------+-----------+---------+---------+------+

2 rows in set (0.00 sec)

--查詢數學分數爲89,90,91的同窗。

--方式一

mysql> select *

-> from student

-> where math=89 or math= 90 or math=91;

+------+-----------+---------+---------+------+

+------+-----------+---------+---------+------+

| 1 | 張小明 | 89 | 78 | 90 |

| 4 | 李一 | 88 | 98 | 90 |

+------+-----------+---------+---------+------+

2 rows in set(0.00 sec)

--方式二

mysql> select * from student where math in(89,90,91);

+------+-----------+---------+---------+------+

+------+-----------+---------+---------+------+

| 1 | 張小明 | 89 | 78 | 90 |

| 4 | 李一 | 88 | 98 | 90 |

+------+-----------+---------+---------+------+

2 rows in set(0.00 sec)

--查詢數學分數不爲89,90,91的同窗。

mysql> select * from student where math not in(89,90,91);

+------+-----------+---------+---------+------+

+------+-----------+---------+---------+------+

| 2 | 李進 | 67 | 98 | 56 |

| 3 | 王五 | 87 | 78 | 77 |

| 5 | 李來財 | 82 | 84 | 67 |

| 6 | 張進寶 | 55| 85 | 45 |

| 7 | 黃蓉 | 75 | 65 | 30 |

| 8 | 張一李 | 75 | 65 | 30 |

| 9 | 何李 | 75 | 65 | 30 |

| 10 | 單 | 75 | 65 | 30 |

| 12 | jack | 75 | 65 | 40 |

| 13 | marry | 75 | 65 | 60 |

+------+-----------+---------+---------+------+

10 rows in set(0.00 sec)

--查詢全部姓'李'的學生

mysql> select * from student where name like '李%';

+------+-----------+---------+---------+------+

+------+-----------+---------+---------+------+

| 2 | 李進 | 67 | 98 | 56 |

| 4 | 李一 | 88 | 98 | 90 |

| 5 | 李來財 | 82 | 84 | 67 |

| 11 | 李 | 75 | 65 | NULL |

+------+-----------+---------+---------+------+

4 rows in set(0.00 sec)

--查詢李_(_表明一個字符，%表明多個字符)

mysql> select * from student where name like '李_';

+------+--------+---------+---------+------+

+------+--------+---------+---------+------+

| 2 | 李進 | 67 | 98 | 56 |

| 4 | 李一 | 88 | 98 | 90 |

+------+--------+---------+---------+------+

2 rows in set(0.00 sec)

--模糊查詢，查詢有姓名中有'李'的字

mysql> select * from student where name like '%李%';

+------+-----------+---------+---------+------+

+------+-----------+---------+---------+------+

| 2 | 李進 | 67 | 98 | 56 |

| 4 | 李一 | 88 | 98 | 90 |

| 5 | 李來財 | 82| 84 | 67 |

| 8 | 張一李 | 75 | 65 | 30 |

| 9 | 何李 | 75 | 65 | 30 |

| 11 | 李 | 75 | 65 | NULL |

+------+-----------+---------+---------+------+

6 rows in set(0.00 sec)

--查詢數學成績爲空的記錄

mysql> select * from student where math is null;

+------+------+---------+---------+------+

+------+------+---------+---------+------+

| 11 | 李 | 75 | 65 | NULL |

+------+------+---------+---------+------+

1 row in set(0.00 sec)

--查詢數學成績不爲空的記錄

mysql> select * from student where math is not null;

+------+-----------+---------+---------+------+

+------+-----------+---------+---------+------+

| 1 | 張小明 | 89 | 78 | 90 |

| 2 | 李進 | 67 | 98 | 56 |

| 3 | 王五 | 87 | 78 | 77 |

| 4 | 李一 | 88 | 98 | 90 |

| 5 | 李來財 | 82 | 84 | 67 |

| 6 | 張進寶 | 55 | 85 | 45 |

| 7 | 黃蓉 | 75 | 65 | 30 |

| 8 | 張一李 | 75 | 65 | 30 |

| 9 | 何李 | 75 | 65 | 30 |

| 10 | 單 | 75 | 65 | 30 |

| 12 | jack | 75 | 65 | 40 |

| 13 | marry | 75 | 65 | 60 |

+------+-----------+---------+---------+------+

12 rows in set(0.00 sec)

--查詢數學和語法大於80的記錄

mysql> select * from student where math>80 &&chinese>80;

+------+-----------+---------+---------+------+

+------+-----------+---------+---------+------+

| 1 | 張小明 | 89 | 78 | 90 |

| 4 | 李一 | 88 | 98 | 90 |

+------+-----------+---------+---------+------+

2 rows in set(0.00 sec)

mysql> select * from student where math>80 and chinese>80;

+------+-----------+---------+---------+------+

+------+-----------+---------+---------+------+

| 1 | 張小明 | 89 | 78 | 90 |

| 4 | 李一 | 88 | 98 | 90 |

+------+-----------+---------+---------+------+

2 rows in set(0.00 sec)

l 使用order by 子句排序查詢結果。

語法:

SELECT column1,column2. column3..

FROM table;

order by columnasc|desc

l Order by指定排序的列，排序的列便可是表中的列名，也能夠是select語句後指定的列名。

l Asc升序、Desc 降序

l ORDER BY子句應位於SELECT語句的結尾。

--按數學成績排序輸出desc降序

asc(默認升序)

mysql> select name,math from student order by math desc;

+-----------+------+

| name | math |

+-----------+------+

| 張小明 | 90 |

| 李一 | 90 |

| 王五 | 77 |

| 李來財 | 67 |

| marry | 60 |

| 李進 | 56 |

| 張進寶 | 45 |

| jack | 40 |

| 張一李 | 30 |

| 何李 | 30 |

| 單 | 30 |

| 黃蓉 | 30 |

| 李 | NULL |

+-----------+------+

13 rows in set(0.00 sec)

mysql> select name,math from student order by math;

+-----------+------+

| name | math |

+-----------+------+

| 李 | NULL |

| 黃蓉 | 30 |

| 單 | 30 |

| 何李 | 30 |

| 張一李 | 30 |

| jack | 40 |

| 張進寶 | 45 |

| 李進 | 56 |

| marry | 60 |

| 李來財 | 67|

| 王五 | 77 |

| 李一 | 90 |

| 張小明 | 90 |

+-----------+------+

13 rows in set(0.00 sec)

mysql> select name,math from student order by math asc;

+-----------+------+

| name | math |

+-----------+------+

| 李 | NULL |

| 黃蓉 | 30 |

| 單 | 30 |

| 何李 | 30 |

| 張一李 | 30 |

| jack | 40 |

| 張進寶 | 45 |

| 李進 | 56 |

| marry | 60 |

| 李來財 | 67 |

| 王五 | 77 |

| 李一 | 90 |

| 張小明 | 90 |

+-----------+------+

13 rows in set(0.00 sec)

--對總分降序輸出

mysql> selectname,(chinese+math+english) as總分 from student orderby (chinese+math+english) desc;

+-----------+--------+

| name | 總分 |

+-----------+--------+

| 李一 | 276 |

| 張小明 | 257 |

| 王五 | 242 |

| 李來財 | 233 |

| 李進 | 221 |

| marry | 200 |

| 張進寶 | 185 |

| jack | 180 |

| 張一李 | 170 |

| 何李 | 170 |

| 單 | 170 |

| 黃蓉 | 170 |

| 李 | NULL |

+-----------+--------+

13 rows in set (0.00 sec)

--對姓名的學生按總分進行排序

mysql> select name,math+chinese+englishas總分

-> from student

-> where name LIKE '李%'

-> order bymath+chinese+english desc;

+-----------+--------+

| name | 總分 |

+-----------+--------+

| 李一 | 276 |

| 李來財 | 233 |

| 李進 | 221 |

| 李 | NULL |

+-----------+--------+

4 rows in set (0.00 sec)

===================函數==================

l Count(列名)返回某一列，行的總數，除null外

語法:

Select count(*)|count(列名) fromtablename[WHERE where_definition]

--統計學生人數

mysql>select count(*) as學生人數 from student;

+--------------+

| 學生人數 |

+--------------+

| 13 |

+--------------+

1 row in set (0.00 sec)

--統計數學成績大於80的人數

mysql>select count(*) as數學大於80的人數from student where math>80

+-------------------------+

| 數學大於80的人數 |

+-------------------------+

| 2 |

+-------------------------+

1 row in set (0.00 sec)

--統計數學成績的人數,爲12,由於有一個null,count不進行統計

mysql> selectcount(math) from student;

+-------------+

| count(math) |

+-------------+

| 12 |

+-------------+

1 row in set (0.00 sec)

--統計學生數學的總分

l Sum函數返回知足where條件的行的和

Select sum(列名)｛,sum(列名)…｝ fromtablename [WHERE where_definition]

mysql> selectsum(math) as '數學總分' from student;

+--------------+

| 數學總分 |

+--------------+

| 645 |

+--------------+

1 row in set (0.00 sec)

mysql> selectsum(math)+ sum(chinese)+ sum(english)as '語數外總分' from student;

+-----------------+

| 語數外總分 |

+-----------------+

| 2614 |

+-----------------+

1 row in set (0.00 sec)

AVG函數返回知足where條件的一列的平均值

Select sum(列名)｛,sum(列名)…｝ from tablename

[WHERE where_definition]

--統計語文平均分

mysql> selectsum(chinese)/count(*) as '語文平均分'from student;

+-------------------+

| 語文平均分 |

+-------------------+

| 76.38461538461539 |

+-------------------+

1 row in set (0.00 sec)

mysql> selectavg(chinese) as '語文平均分'from student;

+-------------------+

| 語文平均分 |

+-------------------+

| 76.38461538461539 |

+-------------------+

1 row in set (0.00 sec)

--求班級總分平均數

mysql> select (sum(math)+sum(english)+sum(chinese))/count(*)as '總分平均數' from student;

+--------------------+

| 總分平均數 |

+--------------------+

| 201.07692307692307 |

+--------------------+

1 row in set (0.00 sec)

l Max/min函數返回知足where條件的一列的最大/最小值

語法:

Select max(列名)from tablename [WHERE where_definition]

Max/min函數返回知足where條件的一列的最大/最小值求班級最高分和最低分。（數值範圍在統計中特別有用）

max(),min()，當max()和min()函數位於日期類型時，分別取得最近日期和最先日期,用於varchar是按碼錶的順序進行查詢

mysql> select min(chinese) as語文最低分,max(chinese) as 語文最高分 from student;

+-----------------+-----------------+

| 語文最低分 | 語文最高分 |

+-----------------+-----------------+

| 55 | 89 |

+-----------------+-----------------+

1 row in set (0.00sec)

mysql> droptable if exists teacher;

Query OK, 0 rowsaffected, 1 warning (0.00 sec)

mysql> createtable teacher(

-> id int,

-> name varchar(20),

-> birthday date

-> );

Query OK, 0 rowsaffected (0.61 sec)

mysql> insertinto teacher(id,name,birthday) values(1,'jack','2011-1-1');

Query OK, 1 rowaffected (0.14 sec)

mysql> insertinto teacher(id,name,birthday) values(2,'marry','2011-2-2');

Query OK, 1 rowaffected (0.08 sec)

mysql> insertinto teacher(id,name,birthday) values(3,'sisi','2011-3-3');

Query OK, 1 rowaffected (0.53 sec)

mysql>

mysql> selectmax(birthday),min(birthday)

-> from teacher;

+---------------+---------------+

| max(birthday) |min(birthday) |

+---------------+---------------+

| 2011-03-03 | 2011-01-01 |

+---------------+---------------+

1 row in set (0.00sec)

mysql>

--order表

mysql> createtable orders(

-> id int,

-> product varchar(20),

-> price float

-> );

Query OK, 0 rowsaffected (0.90 sec)

mysql>

mysql> insertinto orders(id,product,price) values(1,'電視',900);

Query OK, 1 rowaffected (0.05 sec)

mysql> insert intoorders(id,product,price) values(2,'洗衣機',100);

Query OK, 1 rowaffected (0.06 sec)

mysql> insertinto orders(id,product,price) values(3,'洗衣粉',90);

Query OK, 1 rowaffected (0.44 sec)

mysql> insertinto orders(id,product,price) values(4,'桔子',10);

Query OK, 1 rowaffected (0.07 sec)

mysql> insertinto orders(id,product,price) values(5,'洗衣粉',80);

Query OK, 1 rowaffected (0.06 sec)

mysql>

mysql> select *from orders;

+------+-----------+-------+

| id | product | price |

+------+-----------+-------+

| 1 | 電視 | 900 |

| 2 | 洗衣機 | 100 |

| 3 | 洗衣粉 | 90 |

| 4 | 桔子 | 10 |

| 5 | 洗衣粉 | 80 |

+------+-----------+-------+

5 rows in set(0.00 sec)

l 使用group by 子句對列進行分組

語法:

SELECT column1,column2. column3.. FROM table;

group bycolumn

--對訂單表中商品歸類後，顯示每一類商品的總價

l 使用group by 子句對列進行分組

mysql> select product as類別名,sum(price) as商品類別總價

-> from orders

-> group by product;

+-----------+--------------------+

| 類別名 | 商品類別總價 |

+-----------+--------------------+

| 桔子 | 10 |

| 洗衣機 | 100 |

| 洗衣粉 | 170 |

| 電視 | 900 |

+-----------+--------------------+

4 rows in set(0.00 sec)

--查詢購買了幾類商品，而且每類總價大於100的商品

l 使用having 子句組過濾

mysql> select product as類別名,sum(price) as商品類別總價

-> from orders

-> group by product

-> having sum(price) > 100;

+-----------+--------------------+

| 類別名 | 商品類別總價 |

+-----------+--------------------+

| 洗衣粉 | 170 |

| 電視 | 900 |

+-----------+--------------------+

2 rows inset (0.00 sec)

l Having和where都可實現過濾，但在having可使用合計函數,having一般跟在group by後，它做用於組。

where主要用於行過濾器

having主要用於類別過濾器，一般有having就必定出現group by,但有group by的地方，不必定出現having。

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