mysql基础语句大全(MySQL基本查询)
表的增删查改
CRUD : Create(创建), Retrieve(读取) , Update(更新) , Delete(删除)
Create(创建)
基本语法:
INSERT [INTO] table_name [(column [, column] ...)] VALUES (value_list) [, (value_list)] ... value_list: value, [, value] ...案例:
mysql> create table students ( -> id int unsigned primary key auto_increment, -> sn int not null unique comment 学号, -> name varchar(20) not null, -> email varchar(20) -> )engine=innodb default charset=utf8; Query OK, 0 rows affected (0.03 sec) mysql> desc students; +-------+------------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-------+------------------+------+-----+---------+----------------+ | id | int(10) unsigned | NO | PRI | NULL | auto_increment | | sn | int(11) | NO | UNI | NULL | | | name | varchar(20) | NO | | NULL | | | email | varchar(20) | YES | | NULL | | +-------+------------------+------+-----+---------+----------------+ 4 rows in set (0.00 sec)单行数据 + 全列插入
插入两条记录,当value_list 数量和定义表的列的数量及顺序一致时 ,就可以省略value_list 。注意 ,这里在插入的时候 ,也可以不用指定id ,mysql会使用默认的值进行自增 。
mysql> insert into students values (100, 1000, Curry, NULL); Query OK, 1 row affected (0.01 sec) mysql> insert into students values (101, 1001, Durant, 3306@163.com); Query OK, 1 row affected (0.00 sec) mysql> select * from students; +-----+------+--------+--------------+ | id | sn | name | email | +-----+------+--------+--------------+ | 100 | 1000 | Curry | NULL | | 101 | 1001 | Durant | 3306@163.com | +-----+------+--------+--------------+ 2 rows in set (0.00 sec)多行数据 + 指定列插入
插入两条记录 ,value_list 数量必须和指定列数量及顺序一致
mysql> insert into students (id, sn, name) values (102, 1002, Kobe), (103, 1003, Klay); Query OK, 2 rows affected (0.00 sec) Records: 2 Duplicates: 0 Warnings: 0 mysql> select * from students; +-----+------+--------+--------------+ | id | sn | name | email | +-----+------+--------+--------------+ | 100 | 1000 | Curry | NULL | | 101 | 1001 | Durant | 3306@163.com | | 102 | 1002 | Kobe | NULL | | 103 | 1003 | Klay | NULL | +-----+------+--------+--------------+ 4 rows in set (0.00 sec)插入否则更新
由于 主键 或者 唯一键 对应的值已经存在而导致插入失败
主键冲突:
mysql> insert into students (id, sn, name) values (100, 1004, Brown); ERROR 1062 (23000): Duplicate entry 100 for key PRIMARY唯一键冲突:
mysql> insert into students (id, sn, name) values (104, 1003, Bryant); ERROR 1062 (23000): Duplicate entry 1003 for key sn可以选择性的进行同步更新操作 语法:
INSERT ... ON DUPLICATE KEY UPDATE column = value [, column = value] ... mysql> insert into students (id, sn, name) values (104, 1003, Bryant) -> on duplicate key update id=104, name=Bryant; Query OK, 2 rows affected (0.01 sec) mysql> select * from students; +-----+------+--------+--------------+ | id | sn | name | email | +-----+------+--------+--------------+ | 100 | 1000 | Curry | NULL | | 101 | 1001 | Durant | 3306@163.com | | 102 | 1002 | Kobe | NULL | | 104 | 1003 | Bryant | NULL | +-----+------+--------+--------------+ 4 rows in set (0.00 sec) 0 row affected: 表中有冲突数据 ,但冲突数据的值和 update 的值相等 1 row affected: 表中没有冲突数据 ,数据被插入 2 row affected: 表中有冲突数据 ,并且数据已经被更新替换
主键 或者 唯一键 没有冲突 ,则直接插入;
主键 或者 唯一键 如果冲突,则删除后再插入 mysql> replace into students (sn, name) values (1002, Mitchell); Query OK, 2 rows affected (0.00 sec) mysql> select * from students; +-----+------+----------+--------------+ | id | sn | name | email | +-----+------+----------+--------------+ | 100 | 1000 | Curry | NULL | | 101 | 1001 | Durant | 3306@163.com | | 104 | 1003 | Bryant | NULL | | 105 | 1002 | Mitchell | NULL | +-----+------+----------+--------------+ 4 rows in set (0.00 sec) 1 row affected: 表中没有冲突数据 ,数据被插入 2 row affected: 表中有冲突数据 ,删除后重新插入Retrieve(读取)
基础语法:
SELECT [DISTINCT] {* | {column [, column] ...} [FROM table_name] [WHERE ...] [ORDER BY column [ASC | DESC], ...] LIMIT ...案例:
创建表结构:
mysql> create table exam_result ( -> id int unsigned primary key auto_increment, -> name varchar(20) not null comment 姓名, -> chinese float default 0.0 comment 语文成绩, -> math float default 0.0 comment 数学成绩, -> english float default 0.0 comment 英语成绩 -> )engine=innodb default charset=utf8; Query OK, 0 rows affected (0.02 sec)插入测试数据:
mysql> insert into exam_result (name, chinese, math, english) values -> (唐三藏, 67, 98, 56), -> (孙悟空, 87, 78, 77), -> (猪悟能, 88, 98, 90), -> (曹孟德, 82, 84, 67), -> (刘玄德, 55, 85, 45), -> (孙权, 70, 73, 78), -> (宋公明, 75, 65, 30); Query OK, 7 rows affected (0.00 sec) Records: 7 Duplicates: 0 Warnings: 0SELECT列
全列查询通常情况下不建议使用 * 进行全列查询
查询的列越多,意味着需要传输的数据量越大; 可能会影响到索引的使用; mysql> select * from exam_result; +----+-----------+---------+------+---------+ | id | name | chinese | math | english | +----+-----------+---------+------+---------+ | 1 | 唐三藏 | 67 | 98 | 56 | | 2 | 孙悟空 | 87 | 78 | 77 | | 3 | 猪悟能 | 88 | 98 | 90 | | 4 | 曹孟德 | 82 | 84 | 67 | | 5 | 刘玄德 | 55 | 85 | 45 | | 6 | 孙权 | 70 | 73 | 78 | | 7 | 宋公明 | 75 | 65 | 30 | +----+-----------+---------+------+---------+ 7 rows in set (0.00 sec) 指定列查询指定列的顺序不需要按定义表的顺序来
mysql> select id, name, math from exam_result; +----+-----------+------+ | id | name | math | +----+-----------+------+ | 1 | 唐三藏 | 98 | | 2 | 孙悟空 | 78 | | 3 | 猪悟能 | 98 | | 4 | 曹孟德 | 84 | | 5 | 刘玄德 | 85 | | 6 | 孙权 | 73 | | 7 | 宋公明 | 65 | +----+-----------+------+ 7 rows in set (0.00 sec) 查询字段为表达式表达式不包含字段:
mysql> select id, name, 10 from exam_result; +----+-----------+----+ | id | name | 10 | +----+-----------+----+ | 1 | 唐三藏 | 10 | | 2 | 孙悟空 | 10 | | 3 | 猪悟能 | 10 | | 4 | 曹孟德 | 10 | | 5 | 刘玄德 | 10 | | 6 | 孙权 | 10 | | 7 | 宋公明 | 10 | +----+-----------+----+ 7 rows in set (0.00 sec)表达式包含一个字段:
mysql> select id, name, math+10 from exam_result; +----+-----------+---------+ | id | name | math+10 | +----+-----------+---------+ | 1 | 唐三藏 | 108 | | 2 | 孙悟空 | 88 | | 3 | 猪悟能 | 108 | | 4 | 曹孟德 | 94 | | 5 | 刘玄德 | 95 | | 6 | 孙权 | 83 | | 7 | 宋公明 | 75 | +----+-----------+---------+ 7 rows in set (0.00 sec)表达式包含多个字段:
mysql> select id, name, math+chinese+english from exam_result; +----+-----------+----------------------+ | id | name | math+chinese+english | +----+-----------+----------------------+ | 1 | 唐三藏 | 221 | | 2 | 孙悟空 | 242 | | 3 | 猪悟能 | 276 | | 4 | 曹孟德 | 233 | | 5 | 刘玄德 | 185 | | 6 | 孙权 | 221 | | 7 | 宋公明 | 170 | +----+-----------+----------------------+ 7 rows in set (0.00 sec) 查询结果指定别名基础语法:
ELECT column [AS] alias_name [...] FROM table_name; mysql> select id, name, math+chinese+english total from exam_result; +----+-----------+-------+ | id | name | total | +----+-----------+-------+ | 1 | 唐三藏 | 221 | | 2 | 孙悟空 | 242 | | 3 | 猪悟能 | 276 | | 4 | 曹孟德 | 233 | | 5 | 刘玄德 | 185 | | 6 | 孙权 | 221 | | 7 | 宋公明 | 170 | +----+-----------+-------+ 7 rows in set (0.00 sec) 结果去重查询结果重复:
mysql> select math from exam_result; +------+ | math | +------+ | 98 | | 78 | | 98 | | 84 | | 85 | | 73 | | 65 | +------+ 7 rows in set (0.00 sec)查询结果去重:
mysql> select distinct math from exam_result; +------+ | math | +------+ | 98 | | 78 | | 84 | | 85 | | 73 | | 65 | +------+ 6 rows in set (0.00 sec)WHERE 条件
基本比较英语不及格的同学及英语成绩 ( < 60 ):
mysql> select name, english from exam_result where english<60; +-----------+---------+ | name | english | +-----------+---------+ | 唐三藏 | 56 | | 刘玄德 | 45 | | 宋公明 | 30 | +-----------+---------+ 3 rows in set (0.00 sec) BETWEEN AND 条件连接语文成绩在 [80, 90] 分的同学及语文成绩:
使用 AND 进行条件连接
mysql> select name, chinese from exam_result where chinese>=80 and chinese<=90; +-----------+---------+ | name | chinese | +-----------+---------+ | 孙悟空 | 87 | | 猪悟能 | 88 | | 曹孟德 | 82 | +-----------+---------+ 3 rows in set (0.00 sec)使用 BETWEEN AND 条件连接
mysql> select name, chinese from exam_result where chinese between 80 and 90; +-----------+---------+ | name | chinese | +-----------+---------+ | 孙悟空 | 87 | | 猪悟能 | 88 | | 曹孟德 | 82 | +-----------+---------+ 3 rows in set (0.00 sec) OR 条件连接数学成绩是 58 或者 59 或者 98 或者 99 分的同学及数学成绩:
mysql> select name, math from exam_result where math=58 or math=59 or math=98 or math=99; +-----------+------+ | name | math | +-----------+------+ | 唐三藏 | 98 | | 猪悟能 | 98 | +-----------+------+ 2 rows in set (0.00 sec) IN 条件连接数学成绩是 58 或者 59 或者 98 或者 99 分的同学及数学成绩:
mysql> select name, math from exam_result where math in (58,59,98,99); +-----------+------+ | name | math | +-----------+------+ | 唐三藏 | 98 | | 猪悟能 | 98 | +-----------+------+ 2 rows in set (0.00 sec) LIKE 条件匹配查找姓孙的同学:% 匹配任意多个(包括 0 个)任意字符
mysql> select name from exam_result where name like 孙%; +-----------+ | name | +-----------+ | 孙悟空 | | 孙权 | +-----------+ 2 rows in set (0.00 sec)查找孙某同学: _ 匹配严格的一个任意字符
mysql> select name from exam_result where name like 孙_; +--------+ | name | +--------+ | 孙权 | +--------+ 1 row in set (0.00 sec) WHERE 条件中使用表达式总分在 200 分以下的同学:
mysql> select name, chinese+math+english total from exam_result where total<200; ERROR 1054 (42S22): Unknown column total in where clause这里我们发现一个问题 ,where条件查询中不能使用指定别名 ,这是因为chinese+math+english这个字句比where total<200字句先执行,所以MySQL并不认识total这个别名 ,就会报错。
正确写法:
mysql> select name, chinese+math+english total from exam_result where chinese+math+english<200; +-----------+-------+ | name | total | +-----------+-------+ | 刘玄德 | 185 | | 宋公明 | 170 | +-----------+-------+ 2 rows in set (0.00 sec) AND 与 NOT 的使用语文成绩 > 80 并且不姓孙的同学:
mysql> select name,chinese from exam_result where chinese>80 and name not like 孙%; +-----------+---------+ | name | chinese | +-----------+---------+ | 猪悟能 | 88 | | 曹孟德 | 82 | +-----------+---------+ 2 rows in set (0.00 sec) 综合性查询查询孙某同学 ,否则要求总成绩 > 200 并且 语文成绩 < 数学成绩 并且 英语成绩 > 80:
mysql> select name,chinese,math,english,chinese+math+english total from exam_result -> where (name like 孙_) or (chinese+math+english>200 and chinese<math and english>80); +-----------+---------+------+---------+-------+ | name | chinese | math | english | total | +-----------+---------+------+---------+-------+ | 猪悟能 | 88 | 98 | 90 | 276 | | 孙权 | 70 | 73 | 78 | 221 | +-----------+---------+------+---------+-------+ 2 rows in set (0.00 sec) NULL的查询查询 email 号已知的同学姓名:
mysql> select name from students where email is not null; +--------+ | name | +--------+ | Durant | +--------+ 1 row in set (0.00 sec)NULL 和 NULL 的比较 ,= 和 <=> 的区别:
mysql> select NULL=NULL, NULL=1, NULL=0; +-----------+--------+--------+ | NULL=NULL | NULL=1 | NULL=0 | +-----------+--------+--------+ | NULL | NULL | NULL | +-----------+--------+--------+ 1 row in set (0.00 sec) mysql> select NULL<=>NULL, NULL<=>1, NULL<=>0; +-------------+----------+----------+ | NULL<=>NULL | NULL<=>1 | NULL<=>0 | +-------------+----------+----------+ | 1 | 0 | 0 | +-------------+----------+----------+ 1 row in set (0.00 sec)结果排序
基本语法:
-- ASC 为升序(从小到大) -- DESC 为降序(从大到小) -- 默认为 ASC SELECT ... FROM table_name [WHERE ...] ORDER BY column [ASC|DESC], [...]; 升序显示查询姓名及数学成绩 ,按数学成绩升序显示:
mysql> select name,math from exam_result order by math; +-----------+------+ | name | math | +-----------+------+ | 宋公明 | 65 | | 孙权 | 73 | | 孙悟空 | 78 | | 曹孟德 | 84 | | 刘玄德 | 85 | | 唐三藏 | 98 | | 猪悟能 | 98 | +-----------+------+ 7 rows in set (0.00 sec) 降序排序查询姓名 及 eamil ,按 eamil排序显示:
mysql> select name,email from students order by email; +----------+--------------+ | name | email | +----------+--------------+ | Curry | NULL | | Bryant | NULL | | Mitchell | NULL | | Durant | 3306@163.com | +----------+--------------+ 4 rows in set (0.00 sec)NULL 视为比任何值都小 ,升序出现在最上面
多字段排序查询同学各门成绩 ,依次按 数学降序 ,英语升序 ,语文升序的方式显示:
mysql> select name,chinese,math,english from exam_result order by math desc, english asc, chinese asc; +-----------+---------+------+---------+ | name | chinese | math | english | +-----------+---------+------+---------+ | 唐三藏 | 67 | 98 | 56 | | 猪悟能 | 88 | 98 | 90 | | 刘玄德 | 55 | 85 | 45 | | 曹孟德 | 82 | 84 | 67 | | 孙悟空 | 87 | 78 | 77 | | 孙权 | 70 | 73 | 78 | | 宋公明 | 75 | 65 | 30 | +-----------+---------+------+---------+ 7 rows in set (0.00 sec)多字段排序,排序优先级随书写顺序
ORDER BY 使用表达式查询同学及总分 ,由高到低:
mysql> select name, chinese+math+english from exam_result order by chinese+math+english desc; +-----------+----------------------+ | name | chinese+math+english | +-----------+----------------------+ | 猪悟能 | 276 | | 孙悟空 | 242 | | 曹孟德 | 233 | | 唐三藏 | 221 | | 孙权 | 221 | | 刘玄德 | 185 | | 宋公明 | 170 | +-----------+----------------------+ 7 rows in set (0.00 sec)ORDER BY 子句中可以使用列别名:
mysql> select name, chinese+math+english total from exam_result order by total desc; +-----------+-------+ | name | total | +-----------+-------+ | 猪悟能 | 276 | | 孙悟空 | 242 | | 曹孟德 | 233 | | 唐三藏 | 221 | | 孙权 | 221 | | 刘玄德 | 185 | | 宋公明 | 170 | +-----------+-------+ 7 rows in set (0.00 sec) 结合 WHERE 子句 和 ORDER BY 子句查询姓孙的同学或者姓曹的同学数学成绩 ,结果按数学成绩由高到低显示:
mysql> select name,math from exam_result where name like 孙% or name like 曹% order by math desc; +-----------+------+ | name | math | +-----------+------+ | 曹孟德 | 84 | | 孙悟空 | 78 | | 孙权 | 73 | +-----------+------+ 3 rows in set (0.00 sec)筛选分页结果
基础语法:
-- 起始下标为 0 -- 从 0 开始,筛选 n 条结果 SELECT ... FROM table_name [WHERE ...] [ORDER BY ...] LIMIT n; -- 从 s 开始 ,筛选 n 条结果 SELECT ... FROM table_name [WHERE ...] [ORDER BY ...] LIMIT s, n; -- 从 s 开始 ,筛选 n 条结果,比第二种用法更明确 ,建议使用 SELECT ... FROM table_name [WHERE ...] [ORDER BY ...] LIMIT n OFFSET s;建议:对未知表进行查询时 ,最好加一条 LIMIT 1 ,避免因为表中数据过大 ,查询全表数据导致数据库卡死按 id 进行分页 ,每页 3 条记录 ,分别显示 第 1 、2 、3 页 。
案例:第 1 页:
mysql> select id, name, chinese, math, english from exam_result order by id limit 3 offset 0; +----+-----------+---------+------+---------+ | id | name | chinese | math | english | +----+-----------+---------+------+---------+ | 1 | 唐三藏 | 67 | 98 | 56 | | 2 | 孙悟空 | 87 | 78 | 77 | | 3 | 猪悟能 | 88 | 98 | 90 | +----+-----------+---------+------+---------+ 3 rows in set (0.00 sec)第 2 页:
mysql> select id, name, chinese, math, english from exam_result order by id limit 3 offset 3; +----+-----------+---------+------+---------+ | id | name | chinese | math | english | +----+-----------+---------+------+---------+ | 4 | 曹孟德 | 82 | 84 | 67 | | 5 | 刘玄德 | 55 | 85 | 45 | | 6 | 孙权 | 70 | 73 | 78 | +----+-----------+---------+------+---------+ 3 rows in set (0.00 sec)第 3 页 ,如果结果不足 3 个 ,不会有影响:
mysql> select id, name, chinese, math, english from exam_result order by id limit 3 offset 6; +----+-----------+---------+------+---------+ | id | name | chinese | math | english | +----+-----------+---------+------+---------+ | 7 | 宋公明 | 75 | 65 | 30 | +----+-----------+---------+------+---------+ 1 row in set (0.00 sec)Update(更新)
基本语法:
UPDATE table_name SET column = expr [, column = expr ...] [WHERE ...] [ORDER BY ...] [LIMIT ...]更新单列
将孙悟空同学的数学成绩变更为 80 分:
mysql> select name, math from exam_result where name=孙悟空; +-----------+------+ | name | math | +-----------+------+ | 孙悟空 | 78 | +-----------+------+ 1 row in set (0.00 sec) mysql> update exam_result set math=80 where name=孙悟空; Query OK, 1 row affected (0.01 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select name, math from exam_result where name=孙悟空; +-----------+------+ | name | math | +-----------+------+ | 孙悟空 | 80 | +-----------+------+ 1 row in set (0.00 sec)更新多列
将曹孟德同学的数学成绩变更为 60 分 ,语文成绩变更为 70 分:
mysql> select name, math, chinese from exam_result where name=曹孟德; +-----------+------+---------+ | name | math | chinese | +-----------+------+---------+ | 曹孟德 | 84 | 82 | +-----------+------+---------+ 1 row in set (0.00 sec) mysql> update exam_result set math=60, chinese=70 where name=曹孟德; Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select name, math, chinese from exam_result where name=曹孟德; +-----------+------+---------+ | name | math | chinese | +-----------+------+---------+ | 曹孟德 | 60 | 70 | +-----------+------+---------+ 1 row in set (0.00 sec)更新值为原值基础上变更
将总成绩倒数前三的 3 位同学的数学成绩加上 30 分:
mysql> update exam_result set math=math+30 order by chinese+math+english limit 3; Query OK, 3 rows affected (0.00 sec) Rows matched: 3 Changed: 3 Warnings: 0 mysql> select name, math from exam_result; +-----------+------+ | name | math | +-----------+------+ | 唐三藏 | 98 | | 孙悟空 | 80 | | 猪悟能 | 98 | | 曹孟德 | 90 | | 刘玄德 | 115 | | 孙权 | 73 | | 宋公明 | 95 | +-----------+------+ 7 rows in set (0.00 sec) 更新全表将所有同学的语文成绩更新为原来的 2 倍:
mysql> select name, chinese from exam_result; +-----------+---------+ | name | chinese | +-----------+---------+ | 唐三藏 | 67 | | 孙悟空 | 87 | | 猪悟能 | 88 | | 曹孟德 | 70 | | 刘玄德 | 55 | | 孙权 | 70 | | 宋公明 | 75 | +-----------+---------+ 7 rows in set (0.00 sec) mysql> update exam_result set chinese=chinese*2; Query OK, 7 rows affected (0.00 sec) Rows matched: 7 Changed: 7 Warnings: 0 mysql> select name, chinese from exam_result; +-----------+---------+ | name | chinese | +-----------+---------+ | 唐三藏 | 134 | | 孙悟空 | 174 | | 猪悟能 | 176 | | 曹孟德 | 140 | | 刘玄德 | 110 | | 孙权 | 140 | | 宋公明 | 150 | +-----------+---------+ 7 rows in set (0.00 sec)Delete(删除)
基础语法:
DELETE FROM table_name [WHERE ...] [ORDER BY ...] [LIMIT ...]删除单条记录
删除孙悟空同学的考试成绩:
mysql> select * from exam_result where name=孙悟空; +----+-----------+---------+------+---------+ | id | name | chinese | math | english | +----+-----------+---------+------+---------+ | 2 | 孙悟空 | 174 | 80 | 77 | +----+-----------+---------+------+---------+ 1 row in set (0.00 sec) mysql> delete from exam_result where name=孙悟空; Query OK, 1 row affected (0.00 sec) mysql> select * from exam_result where name=孙悟空; Empty set (0.00 sec)删除整表
注意:删除整表操作要慎用!
准备测试表:
mysql> create table for_delete ( -> id int unsigned primary key auto_increment, -> name varchar(20) -> )engine=innodb default charset=utf8; Query OK, 0 rows affected (0.02 sec)插入测试数据:
mysql> insert into for_delete (name) values (a), (b), (c); Query OK, 3 rows affected (0.00 sec) Records: 3 Duplicates: 0 Warnings: 0 mysql> select * from for_delete; +----+------+ | id | name | +----+------+ | 1 | a | | 2 | b | | 3 | c | +----+------+ 3 rows in set (0.00 sec)删除整表数据:
mysql> delete from for_delete; Query OK, 3 rows affected (0.00 sec) mysql> select * from for_delete; Empty set (0.00 sec)再插入一条数据,自增 id 在原值上增长:
mysql> insert into for_delete (name) values (d); Query OK, 1 row affected (0.00 sec) mysql> select * from for_delete; +----+------+ | id | name | +----+------+ | 4 | d | +----+------+ 1 row in set (0.00 sec)查看表结构 ,会有 AUTO_INCREMENT=n 项:
mysql> show create table for_delete \G *************************** 1. row *************************** Table: for_delete Create Table: CREATE TABLE `for_delete` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(20) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8 1 row in set (0.00 sec)说明:虽然delete语句删
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