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    MySQL单表查询常见操作实例总结

    本文实例总结了MySQL单表查询常见操作。分享给大家供大家参考,具体如下:

    创建fruits表:

    CREATE TABLE fruits
    (
     f_id  char(10)   NOT NULL,
     s_id  INT NOT NULL,
     f_name char(255)   NOT NULL,
     f_price decimal(8,2) NOT NULL,
     PRIMARY KEY(f_id)
    ) ;
    INSERT INTO fruits (f_id, s_id, f_name, f_price)
    VALUES('a1', 101,'apple',5.2),
    ('b1',101,'blackberry', 10.2),
    ('bs1',102,'orange', 11.2),
    ('bs2',105,'melon',8.2),
    ('t1',102,'banana', 10.3),
    ('t2',102,'grape', 5.3),
    ('o2',103,'coconut', 9.2),
    ('c0',101,'cherry', 3.2),
    ('a2',103, 'apricot',2.2),
    ('l2',104,'lemon', 6.4),
    ('b2',104,'berry', 7.6),
    ('m1',106,'mango', 15.6),
    ('m2',105,'xbabay', 2.6),
    ('t4',107,'xbababa', 3.6),
    ('m3',105,'xxtt', 11.6),
    ('b5',107,'xxxx', 3.6);
    
    

    常用查询:

    SELECT * FROM fruits;
    select f_name,f_price from fruits;
    select f_name,f_price from fruits where f_price=10.2;
    select f_name,f_price from fruits where f_price10;
    select * from fruits where s_id in (101,102) order by f_name;
    select * from fruits where s_id not in (101,102) order by f_name;
    select f_name,f_price from fruits where f_price between 2.00 and 10.20;
    select f_name,f_price from fruits where f_price not between 2.00 and 10.20;
    select f_name,f_price from fruits where f_name like "b%";
    select f_name,f_price from fruits where f_name like "%g%";
    select f_name,f_price from fruits where f_name like "b%y";
    select f_name,f_price from fruits where f_name like "____y";
    
    

    创建customers表:

    CREATE TABLE customers
    (
     c_id   int    NOT NULL AUTO_INCREMENT,
     c_name  char(50) NOT NULL,
     c_address char(50) NULL,
     c_city  char(50) NULL,
     c_zip   char(10) NULL,
     c_contact char(50) NULL,
     c_email  char(255) NULL,
     PRIMARY KEY (c_id)
    );
    INSERT INTO customers(c_id, c_name, c_address, c_city, c_zip, c_contact, c_email)
    VALUES(10001, 'RedHook', '200 Street ', 'Tianjin', '300000', 'LiMing', 'LMing@163.com'),
    (10002, 'Stars', '333 Fromage Lane', 'Dalian', '116000', 'Zhangbo','Jerry@hotmail.com'),
    (10003, 'Netbhood', '1 Sunny Place', 'Qingdao', '266000', 'LuoCong', NULL),
    (10004, 'JOTO', '829 Riverside Drive', 'Haikou', '570000', 'YangShan', 'sam@hotmail.com');
    
    

    常用查询语句:

    select c_id,c_name,c_email from customers where c_email is null;
    select c_id,c_name,c_email from customers where c_email is not null;
    select f_name,f_price from fruits where s_id=101 and f_price>=5;
    select f_name,f_price from fruits where s_id in (101,102) and f_price >=5 and f_name="apple";
    select f_name,f_price from fruits where s_id=101 or s_id=102;
    
    

    使用in操作更加简洁明了

    select f_name,f_price
    from fruits
    where s_id in (101 ,102);
    
    

    字段不重复

    SELECT DISTINCT s_id FROM fruits;
    select f_name from fruits ORDER BY f_name;
    
    

    如果第一列数据中没有相同值,将不再对第二列进行排序。

    SELECT f_name, f_price
    FROM fruits
    ORDER BY f_name, f_price;
    
    

    按价格降序排列,desc为降序,默认为升序。

    SELECT f_name, f_price FROM fruits ORDER BY f_price desc;
    SELECT f_name, f_price FROM fruits ORDER BY f_price desc,f_name;
    SELECT s_id, COUNT(*) AS Total FROM fruits GROUP BY s_id;
    SELECT s_id, GROUP_CONCAT(f_name) AS Names FROM fruits GROUP BY s_id;
    
    

    使用having过滤分组

    SELECT s_id, GROUP_CONCAT(f_name) AS Names
    FROM fruits
    GROUP BY s_id having count(f_name)>1;
    
    

    group by 子句中使用with rollup

    SELECT s_id, COUNT(*) AS Total FROM fruits GROUP BY s_id WITH ROLLUP;
    SELECT * from fruits group by s_id,f_name;
    
    

    创建orderitems表:

    CREATE TABLE orderitems
    (
     o_num   int     NOT NULL,
     o_item   int     NOT NULL,
     f_id    char(10)   NOT NULL,
     quantity  int     NOT NULL,
     item_price decimal(8,2) NOT NULL,
     PRIMARY KEY (o_num,o_item)
    ) ;
    INSERT INTO orderitems(o_num, o_item, f_id, quantity, item_price)
    VALUES(30001, 1, 'a1', 10, 5.2),
    (30001, 2, 'b2', 3, 7.6),
    (30001, 3, 'bs1', 5, 11.2),
    (30001, 4, 'bs2', 15, 9.2),
    (30002, 1, 'b3', 2, 20.0),
    (30003, 1, 'c0', 100, 10),
    (30004, 1, 'o2', 50, 2.50),
    (30005, 1, 'c0', 5, 10),
    (30005, 2, 'b1', 10, 8.99),
    (30005, 3, 'a2', 10, 2.2),
    (30005, 4, 'm1', 5, 14.99);
    
    

    常用查询语句:

    SELECT o_num, SUM(quantity * item_price) AS orderTotal
    FROM orderitems
    GROUP BY o_num
    HAVING SUM(quantity*item_price) >= 100;
    SELECT o_num, SUM(quantity * item_price) AS orderTotal
    FROM orderitems
    GROUP BY o_num
    HAVING SUM(quantity*item_price) >= 100
    order by ordertotal;
    SELECT * From fruits LIMIT 8;
    
    

    从第五行开始,读取3行

    SELECT * From fruits LIMIT 4,3;
    
    

    【例.1】从fruits表中检索所有字段的数据

    SELECT * FROM fruits;
    SELECT f_id, s_id ,f_name, f_price FROM fruits;
    
    

    【例.2】查询当前表中f_name列所有水果名称,输入如下语句:

    SELECT f_name FROM fruits;
    
    

    【例.3】例如,从fruits表中获取f_name和f_price两列,输入如下语句:

    SELECT f_name, f_price FROM fruits;
    
    

    【例.4】查询价格为10.2元的水果的名称,输入如下语句:

    SELECT f_name, f_price
    FROM fruits
    WHERE f_price = 10.2;
    
    

    【例.5】查找名称为“apple”的水果的价格,输入如下语句:

    SELECT f_name, f_price
    FROM fruits
    WHERE f_name = 'apple';
    
    

    【例.6】查询价格小于10的水果的名称,输入如下语句:

    SELECT f_name, f_price
    FROM fruits
    WHERE f_price  10;
    
    

    【例.7】s_id为101和102的记录,输入如下语句:

    SELECT s_id,f_name, f_price
    FROM fruits
    WHERE s_id IN (101,102)
    ORDER BY f_name;
    
    

    【例.8】查询所有s_id不等于101也不等于102的记录,输入如下语句:

    SELECT s_id,f_name, f_price
    FROM fruits
    WHERE s_id NOT IN (101,102)
    ORDER BY f_name;
    
    

    【例.9】查询价格在2.00元到10.5元之间水果名称和价格

    SELECT f_name, f_price
    FROM fruits
    WHERE f_price BETWEEN 2.00 AND 10.20;
    
    

    【例.10】查询价格在2.00元到10.5元之外的水果名称和价格

    SELECT f_name, f_price
    FROM fruits
    WHERE f_price NOT BETWEEN 2.00 AND 10.20;
    
    

    【例.11】查找所有以‘b'字母开头的水果,输入如下语句:

    SELECT f_id, f_name
    FROM fruits
    WHERE f_name LIKE 'b%';
    
    

    【例.12】在fruits表中,查询f_name中包含字母‘g'的记录

    SELECT f_id, f_name
    FROM fruits
    WHERE f_name LIKE '%g%';
    
    

    【例.13】查询以‘b'开头,并以‘y'结尾的水果的名称

    SELECT f_name
    FROM fruits
    WHERE f_name LIKE 'b%y';
    
    

    【例7.14】在fruits表中,查询以字母‘y'结尾,且‘y'前面只有4个字母的记录

    SELECT f_id, f_name
    FROM fruits
    WHERE f_name LIKE '____y';
    
    

    【例.15】查询customers表中c_email为空的记录的c_id、c_name和c_email字段值:

    SELECT c_id, c_name,c_email
    FROM customers
    WHERE c_email IS NULL;
    
    

    【例.16】查询customers表中c_email不为空的记录的c_id、c_name和c_email字段值

    SELECT c_id, c_name,c_email
    FROM customers
    WHERE c_email IS NOT NULL;
    
    

    【例.17】在fruits表中查询s_id = ‘101',并且f_price大于5的记录价格和名称

    SELECT f_id, f_price, f_name
    FROM fruits
    WHERE s_id = '101' AND f_price >=5;
    
    

    【例.18】在fruits表中查询s_id = ‘101'或者'102',并且f_price大于5,并且f_name='apple'的记录价格和名称

    SELECT f_id, f_price, f_name
    FROM fruits
    WHERE s_id IN('101', '102') AND f_price >= 5 AND f_name = 'apple';
    
    

    【例.19】查询s_id=101或者s_id=102的水果供应商的f_price和f_name,SQL语句如下:

    SELECT s_id,f_name, f_price
    FROM fruits
    WHERE s_id = 101 OR s_id = 102;
    
    

    【例.20】查询s_id=101或者s_id=102的水果供应商的f_price和f_name

    SELECT s_id,f_name, f_price
    FROM fruits
    WHERE s_id IN(101,102);
    
    

    【例.21】查询fruits表中s_id字段的值,并返回s_id字段值不得重复

    SELECT DISTINCT s_id FROM fruits;
    
    

    【例.22】查询fruits表的f_name字段值,并对其进行排序

    select f_name from fruits ORDER BY f_name;
    
    

    【例.23】查询fruits表中的f_name和f_price字段,先按f_name排序,再按f_price排序

    SELECT f_name, f_price
    FROM fruits
    ORDER BY f_name, f_price;
    
    

    【例.24】查询fruits表中的f_name和f_price字段,对结果按f_price降序方式排序

    SELECT f_name, f_price
    FROM fruits
    ORDER BY f_price DESC;
    
    

    【例.25】查询fruits表,先按f_price降序排序,再按f_name字段升序排序,SQL语句如下:

    SELECT f_price, f_name
    FROM fruits
    ORDER BY f_price DESC, f_name;
    
    

    【例.26】根据s_id对fruits表中的数据进行分组

    SELECT s_id, COUNT(*) AS Total
    FROM fruits
    GROUP BY s_id;
    
    

    【例.27】根据s_id对fruits表中的数据进行分组,将每个供应商的水果名称显示出来

    SELECT s_id, GROUP_CONCAT(f_name) AS Names
    FROM fruits
    GROUP BY s_id;
    
    

    【例.28】根据s_id对fruits表中的数据进行分组,并显示水果种类大于1的分组信息

    SELECT s_id, GROUP_CONCAT(f_name) AS Names
    FROM fruits
    GROUP BY s_id HAVING COUNT(f_name) > 1;
    
    

    【例.29】根据s_id对fruits表中的数据进行分组,并显示记录数量

    SELECT s_id, COUNT(*) AS Total
    FROM fruits
    GROUP BY s_id WITH ROLLUP;
    
    

    【例.30】根据s_id和f_name字段对fruits表中的数据进行分组, SQL语句如下,

    SELECT * from fruits group by s_id,f_name;
    
    

    【例.31】查询订单价格大于100的订单号和总订单价格

    SELECT o_num, SUM(quantity * item_price) AS orderTotal
    FROM orderitems
    GROUP BY o_num
    HAVING SUM(quantity*item_price) >= 100;
    
    

    【例.32】显示fruits表查询结果的前4行,输入如下语句:

    SELECT * From fruits LIMIT 4;
    
    

    【例.33】在fruits 表中,使用LIMIT子句,返回从第5个记录开始的,行数长度为3的记录

    SELECT * From fruits LIMIT 4, 3;
    
    

    更多关于MySQL相关内容感兴趣的读者可查看本站专题:《MySQL常用函数大汇总》、《MySQL日志操作技巧大全》、《MySQL事务操作技巧汇总》、《MySQL存储过程技巧大全》及《MySQL数据库锁相关技巧汇总》

    希望本文所述对大家MySQL数据库计有所帮助。

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