MySQL学习笔记五
文章目录
- 举例
Mysql 排序
语法
SELECT field1, field2,...fieldN FROM table_name1, table_name2...
ORDER BY field1 [ASC [DESC][默认 ASC]], [field2...] [ASC [DESC][默认 ASC]]
举例
> use RUNOOB;
Database changed
mysql> SELECT * from runoob_tbl ORDER BY submission_date ASC;
+-----------+---------------+---------------+-----------------+
| runoob_id | runoob_title | runoob_author | submission_date |
+-----------+---------------+---------------+-----------------+
| 3 | 学习 Java | RUNOOB.COM | 2015-05-01 |
| 4 | 学习 Python | RUNOOB.COM | 2016-03-06 |
| 1 | 学习 PHP | 菜鸟教程 | 2017-04-12 |
| 2 | 学习 MySQL | 菜鸟教程 | 2017-04-12 |
+-----------+---------------+---------------+-----------------+
4 rows in set (0.01 sec)
mysql> SELECT * from runoob_tbl ORDER BY submission_date DESC;
+-----------+---------------+---------------+-----------------+
| runoob_id | runoob_title | runoob_author | submission_date |
+-----------+---------------+---------------+-----------------+
| 1 | 学习 PHP | 菜鸟教程 | 2017-04-12 |
| 2 | 学习 MySQL | 菜鸟教程 | 2017-04-12 |
| 4 | 学习 Python | RUNOOB.COM | 2016-03-06 |
| 3 | 学习 Java | RUNOOB.COM | 2015-05-01 |
+-----------+---------------+---------------+-----------------+
4 rows in set (0.01 sec)
Mysql 分组
语法
SELECT column_name, function(column_name)
FROM table_name
WHERE column_name operator value
GROUP BY column_name;
举例
SET NAMES utf8;
SET FOREIGN_KEY_CHECKS = 0;
-- ----------------------------
-- Table structure for `employee_tbl`
-- ----------------------------
DROP TABLE IF EXISTS `employee_tbl`;
CREATE TABLE `employee_tbl` (
`id` int(11) NOT NULL,
`name` char(10) NOT NULL DEFAULT '',
`date` datetime NOT NULL,
`signin` tinyint(4) NOT NULL DEFAULT '0' COMMENT '登录次数',
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- ----------------------------
-- Records of `employee_tbl`
-- ----------------------------
BEGIN;
INSERT INTO `employee_tbl` VALUES ('1', '小明', '2016-04-22 15:25:33', '1'), ('2', '小王', '2016-04-20 15:25:47', '3'), ('3', '小丽', '2016-04-19 15:26:02', '2'), ('4', '小王', '2016-04-07 15:26:14', '4'), ('5', '小明', '2016-04-11 15:26:40', '4'), ('6', '小明', '2016-04-04 15:26:54', '2');
COMMIT;
SET FOREIGN_KEY_CHECKS = 1;
> set names utf8;
mysql> SELECT * FROM employee_tbl;
+----+--------+---------------------+--------+
| id | name | date | signin |
+----+--------+---------------------+--------+
| 1 | 小明 | 2016-04-22 15:25:33 | 1 |
| 2 | 小王 | 2016-04-20 15:25:47 | 3 |
| 3 | 小丽 | 2016-04-19 15:26:02 | 2 |
| 4 | 小王 | 2016-04-07 15:26:14 | 4 |
| 5 | 小明 | 2016-04-11 15:26:40 | 4 |
| 6 | 小明 | 2016-04-04 15:26:54 | 2 |
+----+--------+---------------------+--------+
6 rows in set (0.00 sec)
mysql> SELECT name, COUNT(*) FROM employee_tbl GROUP BY name;
+--------+----------+
| name | COUNT(*) |
+--------+----------+
| 小丽 | 1 |
| 小明 | 3 |
| 小王 | 2 |
+--------+----------+
3 rows in set (0.01 sec)
Mysql 连接使用
举例
mysql> use RUNOOB;
Database changed
mysql> SELECT * FROM tcount_tbl;
+---------------+--------------+
| runoob_author | runoob_count |
+---------------+--------------+
| 菜鸟教程 | 10 |
| RUNOOB.COM | 20 |
| Google | 22 |
+---------------+--------------+
3 rows in set (0.01 sec)
mysql> SELECT * from runoob_tbl;
+-----------+---------------+---------------+-----------------+
| runoob_id | runoob_title | runoob_author | submission_date |
+-----------+---------------+---------------+-----------------+
| 1 | 学习 PHP | 菜鸟教程 | 2017-04-12 |
| 2 | 学习 MySQL | 菜鸟教程 | 2017-04-12 |
| 3 | 学习 Java | RUNOOB.COM | 2015-05-01 |
| 4 | 学习 Python | RUNOOB.COM | 2016-03-06 |
| 5 | 学习 C | FK | 2017-04-05 |
+-----------+---------------+---------------+-----------------+
5 rows in set (0.01 sec)
mysql> SELECT a.runoob_id, a.runoob_author, b.runoob_count FROM runoob_tbl a INNER JOIN tcount_tbl b ON a.runoob_author = b.runoob_author;
+-------------+-----------------+----------------+
| a.runoob_id | a.runoob_author | b.runoob_count |
+-------------+-----------------+----------------+
| 1 | 菜鸟教程 | 10 |
| 2 | 菜鸟教程 | 10 |
| 3 | RUNOOB.COM | 20 |
| 4 | RUNOOB.COM | 20 |
+-------------+-----------------+----------------+
4 rows in set (0.00 sec)
mysql> SELECT a.runoob_id, a.runoob_author, b.runoob_count FROM runoob_tbl a, tcount_tbl b WHERE a.runoob_author = b.runoob_author;
+-------------+-----------------+----------------+
| a.runoob_id | a.runoob_author | b.runoob_count |
+-------------+-----------------+----------------+
| 1 | 菜鸟教程 | 10 |
| 2 | 菜鸟教程 | 10 |
| 3 | RUNOOB.COM | 20 |
| 4 | RUNOOB.COM | 20 |
+-------------+-----------------+----------------+
4 rows in set (0.01 sec)
mysql> SELECT a.runoob_id, a.runoob_author, b.runoob_count FROM runoob_tbl a LEFT JOIN tcount_tbl b ON a.runoob_author = b.runoob_author;
+-------------+-----------------+----------------+
| a.runoob_id | a.runoob_author | b.runoob_count |
+-------------+-----------------+----------------+
| 1 | 菜鸟教程 | 10 |
| 2 | 菜鸟教程 | 10 |
| 3 | RUNOOB.COM | 20 |
| 4 | RUNOOB.COM | 20 |
| 5 | FK | NULL |
+-------------+-----------------+----------------+
5 rows in set (0.01 sec)
mysql> SELECT a.runoob_id, a.runoob_author, b.runoob_count FROM runoob_tbl a RIGHT JOIN tcount_tbl b ON a.runoob_author = b.runoob_author;
+-------------+-----------------+----------------+
| a.runoob_id | a.runoob_author | b.runoob_count |
+-------------+-----------------+----------------+
| 1 | 菜鸟教程 | 10 |
| 2 | 菜鸟教程 | 10 |
| 3 | RUNOOB.COM | 20 |
| 4 | RUNOOB.COM | 20 |
| NULL | NULL | 22 |
+-------------+-----------------+----------------+
5 rows in set (0.01 sec)
