Mysql数据库表记录的检索
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一、基本查询语句
二、单表查询
1.查询所有字段
mysql> SELECT * FROM tb_bookinfo; +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 | | 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 | | 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ 3 rows in set (0.00 sec)
2.查询指定字段
mysql> SELECT bookname,author FROM tb_bookinfo; +-----------+-----------+ | bookname | author | +-----------+-----------+ | Java King | LianJiang | | Lian | QiaoJiang | | Tian King | TianJiang | +-----------+-----------+ 3 rows in set (0.00 sec)
3.查询指定数据
mysql> SELECT * FROM tb_bookinfo WHERE bookname=‘Tian King‘; +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ 1 row in set (0.00 sec)
4.带IN关键字的查询
mysql> SELECT bookname,author,price,page,bookcase FROM tb_bookinfo WHERE bookcase IN(1,2); +-----------+-----------+-------+------+----------+ | bookname | author | price | page | bookcase | +-----------+-----------+-------+------+----------+ | Java King | LianJiang | 49.80 | 350 | 1 | | Lian | QiaoJiang | 50.00 | 351 | 2 | +-----------+-----------+-------+------+----------+ 2 rows in set (0.00 sec) mysql> SELECT bookname,author,price,page,bookcase FROM tb_bookinfo WHERE bookcase IN(1,3); +-----------+-----------+-------+------+----------+ | bookname | author | price | page | bookcase | +-----------+-----------+-------+------+----------+ | Java King | LianJiang | 49.80 | 350 | 1 | | Tian King | TianJiang | 51.10 | 352 | 3 | +-----------+-----------+-------+------+----------+ 2 rows in set (0.00 sec)
5.带BETWEEN AND的范围查询
mysql> SELECT * FROM tb_bookinfo WHERE inTime BETWEEN ‘2017-04-17‘ and ‘2017-04-19‘; Empty set (0.00 sec) mysql> SELECT * FROM tb_bookinfo WHERE inTime BETWEEN ‘2018-04-17‘ and ‘2018-04-19‘; +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 | | 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 | | 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ 3 rows in set (0.00 sec) mysql> SELECT * FROM tb_bookinfo WHERE inTime BETWEEN ‘2018-04-17‘ and ‘2018-04-18‘; +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 | | 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ 2 rows in set (0.00 sec) mysql> SELECT * FROM tb_bookinfo WHERE inTime NOT BETWEEN ‘2018-04-17‘ and ‘2018-04-18‘; +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ 1 row in set (0.00 sec)
6.带LIKE的字符匹配查询，通过它可以实现模糊查询，有两种通配符：%（可以匹配一个或多个字符，可以代表任意长度的字符串）和_（只匹配一个字符）
mysql> SELECT * FROM tb_bookinfo WHERE barcode LIKE ‘%71%‘; +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 | | 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 | | 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ 3 rows in set (0.00 sec)
7.用IS NULL关键字查询空值
mysql> SELECT * FROM tb_bookinfo WHERE bookname IS NULL; Empty set (0.00 sec)
8.带AND的多条件查询
mysql> SELECT * FROM tb_bookinfo WHERE bookcase=1 AND del=0; +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ 1 row in set (0.00 sec)
9.带OR的多条件查询
mysql> SELECT * FROM tb_bookinfo WHERE bookcase=1 OR bookcase=2; +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 | | 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ 2 rows in set (0.00 sec)
10.用DISTINCT关键字去除结果中的重复行
mysql> SELECT DISTINCT del FROM tb_bookinfo ; +------+ | del | +------+ | 0 | +------+ 1 row in set (0.00 sec)
11.用ORDER BY关键字对查询结果排序（ASC表示升序，DESC表示降序）
mysql> SELECT * FROM tb_bookinfo ORDER BY price DESC; +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 | | 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 | | 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ 3 rows in set (0.00 sec)
mysql> SELECT * FROM tb_bookinfo ORDER BY typeid ASC; +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 | | 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 | | 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ 3 rows in set (0.00 sec)
12.用GROUP BY关键字分组查询
（1）使用GROUP BY关键字分组查询
mysql> SELECT del,COUNT(*) FROM tb_bookinfo GROUP BY del; +------+----------+ | del | COUNT(*) | +------+----------+ | 0 | 3 | +------+----------+ 1 row in set (0.00 sec)
（2）GROUP BY关键字与GROUP_CONCAT()函数一起使用
mysql> SELECT del,GROUP_CONCAT(barcode) FROM tb_bookinfo GROUP BY del; +------+----------------------------+ | del | GROUP_CONCAT(barcode) | +------+----------------------------+ | 0 | 17120107,17120108,17120109 | +------+----------------------------+ 1 row in set (0.00 sec)
（3）按多个字段进行分组，当第一个字段有相同值时，再按第二个字段进行分组
mysql> SELECT del,barcode FROM tb_bookinfo GROUP BY del,barcode; +------+----------+ | del | barcode | +------+----------+ | 0 | 17120107 | | 0 | 17120108 | | 0 | 17120109 | +------+----------+ 3 rows in set (0.00 sec)
13.用LIMIT限制查询结果的数量(显示前两条数据和从第1个编号开始（记录编号是从0开始的），查询两条数据)
mysql> SELECT * FROM tb_bookinfo ORDER BY price DESC LIMIT 2; +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 | | 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ 2 rows in set (0.00 sec)
mysql> SELECT * FROM tb_bookinfo ORDER BY price DESC LIMIT 1,2; +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ | 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 | | 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 | +----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+ 2 rows in set (0.00 sec)
三、聚合函数查询
聚合函数的最大特点是它们根据一组数据求出一个值。聚合函数的结果值只根据选定行中非NULL的值进行计算，NULL值被忽略。
1.COUNT()函数用于对除“*”以外的任何参数，返回所选择集合中非NULL值的行的数目；对于参数“*”，返回选择集合中所有行的数目，包含NULL值的行。
mysql> SELECT COUNT(*) FROM tb_bookinfo; +----------+ | COUNT(*) | +----------+ | 3 | +----------+ 1 row in set (0.00 sec)
2.SUM()函数
mysql> SELECT price FROM tb_bookinfo; +-------+ | price | +-------+ | 49.80 | | 50.00 | | 51.10 | +-------+ 3 rows in set (0.00 sec) mysql> SELECT SUM(price) FROM tb_bookinfo; +------------+ | SUM(price) | +------------+ | 150.90 | +------------+ 1 row in set (0.00 sec)
3.AVG()函数
mysql> SELECT AVG(price) FROM tb_bookinfo; +------------+ | AVG(price) | +------------+ | 50.299999 | +------------+ 1 row in set (0.00 sec)
4.MAX()函数
mysql> SELECT MAX(price) FROM tb_bookinfo; +------------+ | MAX(price) | +------------+ | 51.10 | +------------+ 1 row in set (0.00 sec)
5.MIN()函数
mysql> SELECT MIN(price) FROM tb_bookinfo; +------------+ | MIN(price) | +------------+ | 49.80 | +------------+ 1 row in set (0.00 sec)
四、连接查询
1.内连接查询
连接是把不同表的记录连到一起的最普遍的方法。内连接是最普遍的连接类型，而且是最匀称的，因为它们要求构成连接的每个表的共有列匹配，不匹配的行将被排除。内连接包括相等连接和自然连接，最常见的例子是相等连接，也就是使用等号运算符根据每个表共有的列的值匹配两个表的行。这种情况下，最后的结果集只包含参加连接的表中与指定字段相符的行。
mysql> SELECT * FROM tb_bookinfo;
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| barcode | bookname | typeid | author | ISBN | price | page | bookcase | inTime | del | id |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
| 17120107 | Java King | 3 | LianJiang | 115 | 49.80 | 350 | 1 | 2018-04-17 | 0 | 1 |
| 17120108 | Lian | 1 | QiaoJiang | 116 | 50.00 | 351 | 2 | 2018-04-18 | 0 | 2 |
| 17120109 | Tian King | 2 | TianJiang | 117 | 51.10 | 352 | 3 | 2018-04-19 | 0 | 3 |
+----------+-----------+--------+-----------+------+-------+------+----------+------------+------+----+
3 rows in set (0.00 sec)
mysql> SELECT * FROM tb_borrow;
+----+----------+--------+------------+------------+----------+--------+
| id | readerid | bookid | borrowTime | backTime | operator | ifback |
+----+----------+--------+------------+------------+----------+--------+
| 1 | 1 | 1 | 2018-04-17 | 2018-04-20 | mr | 1 |
| 2 | 1 | 2 | 2018-04-16 | 2018-04-21 | mr | 1 |
+----+----------+--------+------------+------------+----------+--------+
2 rows in set (0.00 sec)
mysql> SELECT bookid,borrowTime,backTime,ifback,bookname,author,price
-> FROM tb_borrow,tb_bookinfo WHERE tb_borrow.bookid=tb_bookinfo.id;
+--------+------------+------------+--------+-----------+-----------+-------+
| bookid | borrowTime | backTime | ifback | bookname | author | price |
+--------+------------+------------+--------+-----------+-----------+-------+
| 1 | 2018-04-17 | 2018-04-20 | 1 | Java King | LianJiang | 49.80 |
| 2 | 2018-04-16 | 2018-04-21 | 1 | Lian | QiaoJiang | 50.00 |
+--------+------------+------------+--------+-----------+-----------+-------+
2 rows in set (0.00 sec)
2.外连接查询
与内连接不同，外连接是指使用OUTET JOIN关键字将两个表连接起来。外连接生成的结果集不仅包含符合连接条件的行数据，而且含包括左表、右表或两边连接表中所有的数据行。
3.复合条件连接查询
五、子查询
1.带IN关键字的子查询
2.带比较运算符的子查询
3.带EXISTS关键字的子查询
4.带ANY关键字的子查询
5.带ALL关键字的子查询
六、合并查询结果
1.使用UNION关键字
2.使用UNION ALL关键字
七、定义表和字段的别名
1.为表取别名
2.为字段取别名
八、使用正则表达式查询
1.匹配指定字符集中任意一个
2.使用“*”和“+”来匹配多个字符
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