1、介紹
MySQL數據操做： DMLmysql
========================================================正則表達式
在MySQL管理軟件中，能夠經過SQL語句中的DML語言來實現數據的操做，包括sql
- 使用INSERT實現數據的插入
- UPDATE實現數據的更新
- 使用DELETE實現數據的刪除
- 使用SELECT查詢數據以及。
========================================================windows
本節內容包括：ide
插入數據
更新數據
刪除數據
查詢數據函數
2、插入數據INSERT
1. 插入完整數據（順序插入） 語法一： INSERT INTO 表名(字段1,字段2,字段3…字段n) VALUES(值1,值2,值3…值n); 語法二： INSERT INTO 表名 VALUES (值1,值2,值3…值n); 2. 指定字段插入數據 語法： INSERT INTO 表名(字段1,字段2,字段3…) VALUES (值1,值2,值3…); 3. 插入多條記錄 語法： INSERT INTO 表名 VALUES (值1,值2,值3…值n), (值1,值2,值3…值n), (值1,值2,值3…值n); 4. 插入查詢結果 語法： INSERT INTO 表名(字段1,字段2,字段3…字段n) SELECT (字段1,字段2,字段3…字段n) FROM 表2 WHERE …;
3、更新數據UPDATE
語法： UPDATE 表名 SET 字段1=值1, 字段2=值2, WHERE CONDITION; 示例： UPDATE mysql.user SET password=password(‘123’) where user=’root’ and host=’localhost’;
4、刪除數據DELETE
語法： DELETE FROM 表名 WHERE CONITION; 示例： DELETE FROM mysql.user WHERE password=’’; 練習： 更新MySQL root用戶密碼爲mysql123 刪除除從本地登陸的root用戶之外的全部用戶
5、單表查詢
一、單表查詢語法
SELECT 字段1,字段2... FROM 表名 WHERE 條件 GROUP BY field HAVING 篩選 ORDER BY field LIMIT 限制條數
二、關鍵字的執行優先級(重點)
重點中的重點：關鍵字的執行優先級 from where group by having select distinct order by limit
執行過程：
1.找到表:from 2.拿着where指定的約束條件，去文件/表中取出一條條記錄 3.將取出的一條條記錄進行分組group by，若是沒有group by，則總體做爲一組 4.將分組的結果進行having過濾 5.執行select 6.去重 7.將結果按條件排序：order by 8.限制結果的顯示條數
三、簡單查詢
company.employee 員工id id int 姓名 emp_name varchar 性別 sex enum 年齡 age int 入職日期 hire_date date 崗位 post varchar 職位描述 post_comment varchar 薪水 salary double 辦公室 office int 部門編號 depart_id int #建立表 create table employee( id int not null unique auto_increment, name varchar(20) not null, sex enum('male','female') not null default 'male', #大部分是男的 age int(3) unsigned not null default 28, hire_date date not null, post varchar(50), post_comment varchar(100), salary double(15,2), office int, #一個部門一個屋子 depart_id int ); #查看錶結構 mysql> desc employee; +--------------+-----------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +--------------+-----------------------+------+-----+---------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | name | varchar(20) | NO | | NULL | | | sex | enum('male','female') | NO | | male | | | age | int(3) unsigned | NO | | 28 | | | hire_date | date | NO | | NULL | | | post | varchar(50) | YES | | NULL | | | post_comment | varchar(100) | YES | | NULL | | | salary | double(15,2) | YES | | NULL | | | office | int(11) | YES | | NULL | | | depart_id | int(11) | YES | | NULL | | +--------------+-----------------------+------+-----+---------+----------------+ #插入記錄 #三個部門：教學，銷售，運營 insert into employee(name,sex,age,hire_date,post,salary,office,depart_id) values ('egon','male',18,'20170301','老男孩駐沙河辦事處外交大使',7300.33,401,1), #如下是教學部 ('alex','male',78,'20150302','teacher',1000000.31,401,1), ('wupeiqi','male',81,'20130305','teacher',8300,401,1), ('yuanhao','male',73,'20140701','teacher',3500,401,1), ('liwenzhou','male',28,'20121101','teacher',2100,401,1), ('jingliyang','female',18,'20110211','teacher',9000,401,1), ('jinxin','male',18,'19000301','teacher',30000,401,1), ('成龍','male',48,'20101111','teacher',10000,401,1), ('歪歪','female',48,'20150311','sale',3000.13,402,2),#如下是銷售部門 ('丫丫','female',38,'20101101','sale',2000.35,402,2), ('丁丁','female',18,'20110312','sale',1000.37,402,2), ('星星','female',18,'20160513','sale',3000.29,402,2), ('格格','female',28,'20170127','sale',4000.33,402,2), ('張野','male',28,'20160311','operation',10000.13,403,3), #如下是運營部門 ('程咬金','male',18,'19970312','operation',20000,403,3), ('程咬銀','female',18,'20130311','operation',19000,403,3), ('程咬銅','male',18,'20150411','operation',18000,403,3), ('程咬鐵','female',18,'20140512','operation',17000,403,3) ; #ps：若是在windows系統中，插入中文字符，select的結果爲空白，能夠將全部字符編碼統一設置成gbk
#簡單查詢 SELECT id,name,sex,age,hire_date,post,post_comment,salary,office,depart_id FROM employee; SELECT * FROM employee; SELECT name,salary FROM employee; #避免重複DISTINCT SELECT DISTINCT post FROM employee; #經過四則運算查詢 SELECT name, salary*12 FROM employee; SELECT name, salary*12 AS Annual_salary FROM employee; SELECT name, salary*12 Annual_salary FROM employee; #定義顯示格式 CONCAT() 函數用於鏈接字符串 SELECT CONCAT('姓名: ',name,' 年薪: ', salary*12) AS Annual_salary FROM employee; CONCAT_WS() 第一個參數爲分隔符 SELECT CONCAT_WS(':',name,salary*12) AS Annual_salary FROM employee; 結合CASE語句： SELECT ( CASE WHEN NAME = 'egon' THEN NAME WHEN NAME = 'alex' THEN CONCAT(name,'_BIGSB') ELSE concat(NAME, 'SB') END ) as new_name FROM emp;
#1 查出全部員工的名字，薪資,格式爲 # <名字:egon> <薪資:3000> #2 查出全部的崗位（去掉重複） #3 查出全部員工名字，以及他們的年薪,年薪的字段名爲annual_year select concat('<名字:',name,'> ','<薪資:',salary,'>') from employee; select distinct depart_id from employee; select name,salary*12 annual_salary from employee;
四、WHERE約束
where字句中可使用：post
1. 比較運算符：> < >= <= <> !=
2. between 80 and 100 值在10到20之間
3. in(80,90,100) 值是80或90或100
4. like 'egon%'
pattern能夠是%或_，
%表示任意多字符
_表示一個字符
5. 邏輯運算符：在多個條件直接可使用邏輯運算符 and or not ui
#1:單條件查詢 SELECT name FROM employee WHERE post='sale'; #2:多條件查詢 SELECT name,salary FROM employee WHERE post='teacher' AND salary>10000; #3:關鍵字BETWEEN AND SELECT name,salary FROM employee WHERE salary BETWEEN 10000 AND 20000; SELECT name,salary FROM employee WHERE salary NOT BETWEEN 10000 AND 20000; #4:關鍵字IS NULL(判斷某個字段是否爲NULL不能用等號，須要用IS) SELECT name,post_comment FROM employee WHERE post_comment IS NULL; SELECT name,post_comment FROM employee WHERE post_comment IS NOT NULL; SELECT name,post_comment FROM employee WHERE post_comment=''; 注意''是空字符串，不是null ps： 執行 update employee set post_comment='' where id=2; 再用上條查看，就會有結果了 #5:關鍵字IN集合查詢 SELECT name,salary FROM employee WHERE salary=3000 OR salary=3500 OR salary=4000 OR salary=9000 ; SELECT name,salary FROM employee WHERE salary IN (3000,3500,4000,9000) ; SELECT name,salary FROM employee WHERE salary NOT IN (3000,3500,4000,9000) ; #6:關鍵字LIKE模糊查詢 通配符’%’ SELECT * FROM employee WHERE name LIKE 'eg%'; 通配符’_’ SELECT * FROM employee WHERE name LIKE 'al__';
五、分組查詢:GROUP BY
1）什麼是分組？爲何要分組？編碼
#1、首先明確一點：分組發生在where以後，即分組是基於where以後獲得的記錄而進行的 #2、分組指的是：將全部記錄按照某個相同字段進行歸類，好比針對員工信息表的職位分組，或者按照性別進行分組等 #3、爲什麼要分組呢？ 取每一個部門的最高工資 取每一個部門的員工數 取男人數和女人數 小竅門：‘每’這個字後面的字段，就是咱們分組的依據 #4、大前提： 能夠按照任意字段分組，可是分組完畢後，好比group by post，只能查看post字段，若是想查看組內信息，須要藉助於聚合函數
2）ONLY_FULL_GROUP_BYspa
#查看MySQL 5.7默認的sql_mode以下： mysql> select @@global.sql_mode; ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION #！！！注意 ONLY_FULL_GROUP_BY的語義就是肯定select target list中的全部列的值都是明確語義，簡單的說來，在ONLY_FULL_GROUP_BY模式下，target list中的值要麼是來自於彙集函數的結果，要麼是來自於group by list中的表達式的值。 #設置sql_mole以下操做(咱們能夠去掉ONLY_FULL_GROUP_BY模式)： mysql> set global sql_mode='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';
mysql> select @@global.sql_mode; +-------------------+ | @@global.sql_mode | +-------------------+ | | +-------------------+ 1 row in set (0.00 sec) mysql> select * from emp group by post; +----+------+--------+-----+------------+----------------------------+--------------+------------+--------+-----------+ | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | +----+------+--------+-----+------------+----------------------------+--------------+------------+--------+-----------+ | 14 | 張野 | male | 28 | 2016-03-11 | operation | NULL | 10000.13 | 403 | 3 | | 9 | 歪歪 | female | 48 | 2015-03-11 | sale | NULL | 3000.13 | 402 | 2 | | 2 | alex | male | 78 | 2015-03-02 | teacher | NULL | 1000000.31 | 401 | 1 | | 1 | egon | male | 18 | 2017-03-01 | 老男孩駐沙河辦事處外交大使 | NULL | 7300.33 | 401 | 1 | +----+------+--------+-----+------------+----------------------------+--------------+------------+--------+-----------+ 4 rows in set (0.00 sec) #因爲沒有設置ONLY_FULL_GROUP_BY,因而也能夠有結果，默認都是組內的第一條記錄，但其實這是沒有意義的 mysql> set global sql_mode='ONLY_FULL_GROUP_BY'; Query OK, 0 rows affected (0.00 sec) mysql> quit #設置成功後，必定要退出，而後從新登陸方可生效 Bye mysql> use db1; Database changed mysql> select * from emp group by post; #報錯 ERROR 1055 (42000): 'db1.emp.id' isn't in GROUP BY mysql> select post,count(id) from emp group by post; #只能查看分組依據和使用聚合函數 +----------------------------+-----------+ | post | count(id) | +----------------------------+-----------+ | operation | 5 | | sale | 5 | | teacher | 7 | | 老男孩駐沙河辦事處外交大使 | 1 | +----------------------------+-----------+ 4 rows in set (0.00 sec)
3）GROUP BY
單獨使用GROUP BY關鍵字分組 SELECT post FROM employee GROUP BY post; 注意：咱們按照post字段分組，那麼select查詢的字段只能是post，想要獲取組內的其餘相關信息，須要藉助函數 GROUP BY關鍵字和GROUP_CONCAT()函數一塊兒使用 SELECT post,GROUP_CONCAT(name) FROM employee GROUP BY post;#按照崗位分組，並查看組內成員名 SELECT post,GROUP_CONCAT(name) as emp_members FROM employee GROUP BY post; GROUP BY與聚合函數一塊兒使用 select post,count(id) as count from employee group by post;#按照崗位分組，並查看每一個組有多少人
注意：若是咱們用unique的字段做爲分組的依據，則每一條記錄自成一組，這種分組沒有意義。多條記錄之間的某個字段值相同，該字段一般用來做爲分組的依據。
4）聚合函數
#強調：聚合函數聚合的是組的內容，如果沒有分組，則默認一組 示例： SELECT COUNT(*) FROM employee; SELECT COUNT(*) FROM employee WHERE depart_id=1; SELECT MAX(salary) FROM employee; SELECT MIN(salary) FROM employee; SELECT AVG(salary) FROM employee; SELECT SUM(salary) FROM employee; SELECT SUM(salary) FROM employee WHERE depart_id=3;
5）練習
1. 查詢崗位名以及崗位包含的全部員工名字 2. 查詢崗位名以及各崗位內包含的員工個數 3. 查詢公司內男員工和女員工的個數 4. 查詢崗位名以及各崗位的平均薪資 5. 查詢崗位名以及各崗位的最高薪資 6. 查詢崗位名以及各崗位的最低薪資 7. 查詢男員工與男員工的平均薪資，女員工與女員工的平均薪資
#題1：分組 mysql> select post,group_concat(name) from employee group by post; +-----------------------------------------+---------------------------------------------------------+ | post | group_concat(name) | +-----------------------------------------+---------------------------------------------------------+ | operation | 張野,程咬金,程咬銀,程咬銅,程咬鐵 | | sale | 歪歪,丫丫,丁丁,星星,格格 | | teacher | alex,wupeiqi,yuanhao,liwenzhou,jingliyang,jinxin,成龍 | | 老男孩駐沙河辦事處外交大使 | egon | +-----------------------------------------+---------------------------------------------------------+ #題目2： mysql> select post,count(id) from employee group by post; +-----------------------------------------+-----------+ | post | count(id) | +-----------------------------------------+-----------+ | operation | 5 | | sale | 5 | | teacher | 7 | | 老男孩駐沙河辦事處外交大使 | 1 | +-----------------------------------------+-----------+ #題目3： mysql> select sex,count(id) from employee group by sex; +--------+-----------+ | sex | count(id) | +--------+-----------+ | male | 10 | | female | 8 | +--------+-----------+ #題目4： mysql> select post,avg(salary) from employee group by post; +-----------------------------------------+---------------+ | post | avg(salary) | +-----------------------------------------+---------------+ | operation | 16800.026000 | | sale | 2600.294000 | | teacher | 151842.901429 | | 老男孩駐沙河辦事處外交大使 | 7300.330000 | +-----------------------------------------+---------------+ #題目5 mysql> select post,max(salary) from employee group by post; +-----------------------------------------+-------------+ | post | max(salary) | +-----------------------------------------+-------------+ | operation | 20000.00 | | sale | 4000.33 | | teacher | 1000000.31 | | 老男孩駐沙河辦事處外交大使 | 7300.33 | +-----------------------------------------+-------------+ #題目6 mysql> select post,min(salary) from employee group by post; +-----------------------------------------+-------------+ | post | min(salary) | +-----------------------------------------+-------------+ | operation | 10000.13 | | sale | 1000.37 | | teacher | 2100.00 | | 老男孩駐沙河辦事處外交大使 | 7300.33 | +-----------------------------------------+-------------+ #題目七 mysql> select sex,avg(salary) from employee group by sex; +--------+---------------+ | sex | avg(salary) | +--------+---------------+ | male | 110920.077000 | | female | 7250.183750 | +--------+---------------+
六、HAVING過濾
HAVING與WHERE不同的地方在於!!!!!!
#！！！執行優先級從高到低：where > group by > having #1. Where 發生在分組group by以前，於是Where中能夠有任意字段，可是絕對不能使用聚合函數。 #2. Having發生在分組group by以後，於是Having中可使用分組的字段，沒法直接取到其餘字段,可使用聚合函數
mysql> select @@sql_mode; +--------------------+ | @@sql_mode | +--------------------+ | ONLY_FULL_GROUP_BY | +--------------------+ 1 row in set (0.00 sec) mysql> select * from emp where salary > 100000; +----+------+------+-----+------------+---------+--------------+------------+--------+-----------+ | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | +----+------+------+-----+------------+---------+--------------+------------+--------+-----------+ | 2 | alex | male | 78 | 2015-03-02 | teacher | NULL | 1000000.31 | 401 | 1 | +----+------+------+-----+------------+---------+--------------+------------+--------+-----------+ 1 row in set (0.00 sec) mysql> select * from emp having salary > 100000; ERROR 1463 (42000): Non-grouping field 'salary' is used in HAVING clause mysql> select post,group_concat(name) from emp group by post having salary > 10000;#錯誤，分組後沒法直接取到salary字段 ERROR 1054 (42S22): Unknown column 'salary' in 'having clause' mysql> select post,group_concat(name) from emp group by post having avg(salary) > 10000; +-----------+-------------------------------------------------------+ | post | group_concat(name) | +-----------+-------------------------------------------------------+ | operation | 程咬鐵,程咬銅,程咬銀,程咬金,張野 | | teacher | 成龍,jinxin,jingliyang,liwenzhou,yuanhao,wupeiqi,alex | +-----------+-------------------------------------------------------+ 2 rows in set (0.00 sec)
練習：
1. 查詢各崗位內包含的員工個數小於2的崗位名、崗位內包含員工名字、個數 2. 查詢各崗位平均薪資大於10000的崗位名、平均工資 3. 查詢各崗位平均薪資大於10000且小於20000的崗位名、平均工資
#題1： mysql> select post,group_concat(name),count(id) from employee group by post having count(id) < 2; +-----------------------------------------+--------------------+-----------+ | post | group_concat(name) | count(id) | +-----------------------------------------+--------------------+-----------+ | 老男孩駐沙河辦事處外交大使 | egon | 1 | +-----------------------------------------+--------------------+-----------+ #題目2： mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000; +-----------+---------------+ | post | avg(salary) | +-----------+---------------+ | operation | 16800.026000 | | teacher | 151842.901429 | +-----------+---------------+ #題目3： mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000 and avg(salary) <20000; +-----------+--------------+ | post | avg(salary) | +-----------+--------------+ | operation | 16800.026000 | +-----------+--------------+
七、查詢排序:ORDER BY
按單列排序 SELECT * FROM employee ORDER BY salary; SELECT * FROM employee ORDER BY salary ASC; SELECT * FROM employee ORDER BY salary DESC; 按多列排序:先按照age（升序）排序，若是年紀相同，則按照薪資排序 SELECT * from employee ORDER BY age, salary DESC;
練習：
1. 查詢全部員工信息，先按照age升序排序，若是age相同則按照hire_date降序排序
2. 查詢各崗位平均薪資大於10000的崗位名、平均工資,結果按平均薪資升序排列
3. 查詢各崗位平均薪資大於10000的崗位名、平均工資,結果按平均薪資降序排列
#題目1 mysql> select * from employee ORDER BY age asc,hire_date desc; #題目2 mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000 order by avg(salary) asc; +-----------+---------------+ | post | avg(salary) | +-----------+---------------+ | operation | 16800.026000 | | teacher | 151842.901429 | +-----------+---------------+ #題目3 mysql> select post,avg(salary) from employee group by post having avg(salary) > 10000 order by avg(salary) desc; +-----------+---------------+ | post | avg(salary) | +-----------+---------------+ | teacher | 151842.901429 | | operation | 16800.026000 | +-----------+---------------+
八、限制查詢的記錄數:LIMIT
示例： SELECT * FROM employee ORDER BY salary DESC LIMIT 3; #默認初始位置爲0 SELECT * FROM employee ORDER BY salary DESC LIMIT 0,5; #從第0開始，即先查詢出第一條，而後包含這一條在內日後查5條 SELECT * FROM employee ORDER BY salary DESC LIMIT 5,5; #從第5開始，即先查詢出第6條，而後包含這一條在內日後查5條
練習：分頁顯示，每頁5條
mysql> select * from employee limit 0,5; +----+-----------+------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+ | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | +----+-----------+------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+ | 1 | egon | male | 18 | 2017-03-01 | 老男孩駐沙河辦事處外交大使 | NULL | 7300.33 | 401 | 1 | | 2 | alex | male | 78 | 2015-03-02 | teacher | | 1000000.31 | 401 | 1 | | 3 | wupeiqi | male | 81 | 2013-03-05 | teacher | NULL | 8300.00 | 401 | 1 | | 4 | yuanhao | male | 73 | 2014-07-01 | teacher | NULL | 3500.00 | 401 | 1 | | 5 | liwenzhou | male | 28 | 2012-11-01 | teacher | NULL | 2100.00 | 401 | 1 | +----+-----------+------+-----+------------+-----------------------------------------+--------------+------------+--------+-----------+ 5 rows in set (0.00 sec) mysql> select * from employee limit 5,5; +----+------------+--------+-----+------------+---------+--------------+----------+--------+-----------+ | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | +----+------------+--------+-----+------------+---------+--------------+----------+--------+-----------+ | 6 | jingliyang | female | 18 | 2011-02-11 | teacher | NULL | 9000.00 | 401 | 1 | | 7 | jinxin | male | 18 | 1900-03-01 | teacher | NULL | 30000.00 | 401 | 1 | | 8 | 成龍 | male | 48 | 2010-11-11 | teacher | NULL | 10000.00 | 401 | 1 | | 9 | 歪歪 | female | 48 | 2015-03-11 | sale | NULL | 3000.13 | 402 | 2 | | 10 | 丫丫 | female | 38 | 2010-11-01 | sale | NULL | 2000.35 | 402 | 2 | +----+------------+--------+-----+------------+---------+--------------+----------+--------+-----------+ 5 rows in set (0.00 sec) mysql> select * from employee limit 10,5; +----+-----------+--------+-----+------------+-----------+--------------+----------+--------+-----------+ | id | name | sex | age | hire_date | post | post_comment | salary | office | depart_id | +----+-----------+--------+-----+------------+-----------+--------------+----------+--------+-----------+ | 11 | 丁丁 | female | 18 | 2011-03-12 | sale | NULL | 1000.37 | 402 | 2 | | 12 | 星星 | female | 18 | 2016-05-13 | sale | NULL | 3000.29 | 402 | 2 | | 13 | 格格 | female | 28 | 2017-01-27 | sale | NULL | 4000.33 | 402 | 2 | | 14 | 張野 | male | 28 | 2016-03-11 | operation | NULL | 10000.13 | 403 | 3 | | 15 | 程咬金 | male | 18 | 1997-03-12 | operation | NULL | 20000.00 | 403 | 3 | +----+-----------+--------+-----+------------+-----------+--------------+----------+--------+-----------+ 5 rows in set (0.00 sec)
九、使用正則表達式查詢
SELECT * FROM employee WHERE name REGEXP '^ale'; SELECT * FROM employee WHERE name REGEXP 'on$'; SELECT * FROM employee WHERE name REGEXP 'm{2}'; 小結：對字符串匹配的方式 WHERE name = 'egon'; WHERE name LIKE 'yua%'; WHERE name REGEXP 'on$';
小練習：查看全部員工中名字是jin開頭，n或者g結尾的員工信息。
select * from employee where name regexp '^jin.*[gn]$';