MySql技术内幕之MySQL入门(1)
安装
检查系统中是否已经安装了MySQL
sudo netstat -tap | grep mysql
若没有显示已安装结果，则没有安装。否则表示已经安装。
sudo apt-get install mysql-server mysql-client
安装过程中会让输入密码，记得把密码记住。
关于注释
三种写法：
- 用#单行注释
- 用-- 单行注释，注意后面有一空格
- /* */ 多行注释
mysql> SELECT 1+1; # 这个注释直到该行结束
mysql> SELECT 1+1; -- 这个注释直到该行结束
mysql> SELECT 1 /* 这是一个在行中间的注释 */ + 1;
mysql> SELECT 1+
/*
这是一个
多行注释的形式
*/
1;
执行SQL语句
ltq@lab:~$ mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or g.
Your MySQL connection id is 7
Server version: 5.7.19-0ubuntu0.16.04.1 (Ubuntu)
Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.
mysql> SELECT NOW(); # 查询当前日期和时间，使用分号终止语句
+---------------------+
| NOW() |
+---------------------+
| 2017-10-20 22:07:14 |
+---------------------+
1 row in set (0.00 sec)
mysql> SELECT NOW()g # 查询当前日期和时间，使用g终止语句
+---------------------+
| NOW() |
+---------------------+
| 2017-10-20 22:07:56 |
+---------------------+
1 row in set (0.00 sec)
mysql> SELECT NOW(), USER(), VERSION()g # 查询时间，用户，系统版本，并在一列展示
+---------------------+----------------+-------------------------+
| NOW() | USER() | VERSION() |
+---------------------+----------------+-------------------------+
| 2017-10-20 22:08:28 | root@localhost | 5.7.19-0ubuntu0.16.04.1 |
+---------------------+----------------+-------------------------+
1 row in set (0.00 sec)
mysql> SELECT NOW(), USER(), VERSION()G #查询时间，用户，系统版本，并在一行展示
*************************** 1. row ***************************
NOW(): 2017-10-20 22:08:43
USER(): root@localhost
VERSION(): 5.7.19-0ubuntu0.16.04.1
1 row in set (0.00 sec)
mysql> SELECT NOW(),
-> USER(),
-> VERSION()G # 在多行输入
*************************** 1. row ***************************
NOW(): 2017-10-20 22:18:44
USER(): root@localhost
VERSION(): 5.7.19-0ubuntu0.16.04.1
1 row in set (0.00 sec)
mysql> SELECT NOW(),
-> USER(),
-> c # 使用c表示不执行上述语句
mysql> SELECT NOW(); SELECT USER(); SELECT VERSION(); # 在一行输入多条语句
+---------------------+
| NOW() |
+---------------------+
| 2017-10-20 22:21:38 |
+---------------------+
1 row in set (0.00 sec)
+----------------+
| USER() |
+----------------+
| root@localhost |
+----------------+
1 row in set (0.00 sec)
+-------------------------+
| VERSION() |
+-------------------------+
| 5.7.19-0ubuntu0.16.04.1 |
+-------------------------+
1 row in set (0.00 sec)
关于命令大小写
一般用大写字母表示SQL关键字和函数名；
用小写字母表示数据库，表和列的名字。
创建数据库
mysql> CREATE DATABASE sampdb; # 创建数据库
Query OK, 1 row affected (0.00 sec)
mysql> SELECT DATABASE(); # 查看当前数据库，结果为NULL
+------------+
| DATABASE() |
+------------+
| NULL |
+------------+
1 row in set (0.00 sec)
mysql> USE sampdb; # 把sampdb设置为当前默认选择的数据库
Database changed
mysql> SELECT DATABASE(); # 查看当前数据库，结果为NULL
+------------+
| DATABASE() |
+------------+
| sampdb |
+------------+
1 row in set (0.00 sec)
mysql> source create_president.sql # 如果已经在终端cd到create_president.sql路径下，那么则可运行该语句
Query OK, 0 rows affected (0.15 sec)
Query OK, 0 rows affected (0.23 sec)
补充，文件create_president.sql的内容如下：
# Create president table for U.S. Historical League
DROP TABLE IF EXISTS president;
#@ _CREATE_TABLE_
CREATE TABLE president
(
last_name VARCHAR(15) NOT NULL,
first_name VARCHAR(15) NOT NULL,
suffix VARCHAR(5) NULL,
city VARCHAR(20) NOT NULL,
state VARCHAR(2) NOT NULL,
birth DATE NOT NULL,
death DATE NULL
);
#@ _CREATE_TABLE_
查看表的信息
mysql> DESCRIBE president; # 查看president表的结构
+------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| last_name | varchar(15) | NO | | NULL | |
| first_name | varchar(15) | NO | | NULL | |
| suffix | varchar(5) | YES | | NULL | |
| city | varchar(20) | NO | | NULL | |
| state | varchar(2) | NO | | NULL | |
| birth | date | NO | | NULL | |
| death | date | YES | | NULL | |
+------------+-------------+------+-----+---------+-------+
7 rows in set (0.00 sec)
mysql> DESC president; # DESCRIBE的简写为DESC
+------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| last_name | varchar(15) | NO | | NULL | |
| first_name | varchar(15) | NO | | NULL | |
| suffix | varchar(5) | YES | | NULL | |
| city | varchar(20) | NO | | NULL | |
| state | varchar(2) | NO | | NULL | |
| birth | date | NO | | NULL | |
| death | date | YES | | NULL | |
+------------+-------------+------+-----+---------+-------+
7 rows in set (0.00 sec)
mysql> EXPLAIN president;
+------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| last_name | varchar(15) | NO | | NULL | |
| first_name | varchar(15) | NO | | NULL | |
| suffix | varchar(5) | YES | | NULL | |
| city | varchar(20) | NO | | NULL | |
| state | varchar(2) | NO | | NULL | |
| birth | date | NO | | NULL | |
| death | date | YES | | NULL | |
+------------+-------------+------+-----+---------+-------+
7 rows in set (0.00 sec)
mysql> SHOW COLUMNS FROM president;
+------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| last_name | varchar(15) | NO | | NULL | |
| first_name | varchar(15) | NO | | NULL | |
| suffix | varchar(5) | YES | | NULL | |
| city | varchar(20) | NO | | NULL | |
| state | varchar(2) | NO | | NULL | |
| birth | date | NO | | NULL | |
| death | date | YES | | NULL | |
+------------+-------------+------+-----+---------+-------+
7 rows in set (0.00 sec)
mysql> SHOW FIELDS FROM president;
+------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| last_name | varchar(15) | NO | | NULL | |
| first_name | varchar(15) | NO | | NULL | |
| suffix | varchar(5) | YES | | NULL | |
| city | varchar(20) | NO | | NULL | |
| state | varchar(2) | NO | | NULL | |
| birth | date | NO | | NULL | |
| death | date | YES | | NULL | |
+------------+-------------+------+-----+---------+-------+
7 rows in set (0.00 sec)
查看更加详细的信息
mysql> SHOW FULL COLUMNS FROM president; # SHOW FULL COLUMNS 比 SHOW COLUMNS显示更多的信息
+------------+-------------+-------------------+------+-----+---------+-------+---------------------------------+---------+
| Field | Type | Collation | Null | Key | Default | Extra | Privileges | Comment |
+------------+-------------+-------------------+------+-----+---------+-------+---------------------------------+---------+
| last_name | varchar(15) | latin1_swedish_ci | NO | | NULL | | select,insert,update,references | |
| first_name | varchar(15) | latin1_swedish_ci | NO | | NULL | | select,insert,update,references | |
| suffix | varchar(5) | latin1_swedish_ci | YES | | NULL | | select,insert,update,references | |
| city | varchar(20) | latin1_swedish_ci | NO | | NULL | | select,insert,update,references | |
| state | varchar(2) | latin1_swedish_ci | NO | | NULL | | select,insert,update,references | |
| birth | date | NULL | NO | | NULL | | select,insert,update,references | |
| death | date | NULL | YES | | NULL | | select,insert,update,references | |
+------------+-------------+-------------------+------+-----+---------+-------+---------------------------------+---------+
7 rows in set (0.00 sec)
查看与给定模式相匹配的列
如果需要对所查找的信息加以限定，
mysql> DESCRIBE president '%name'; # 查找名称中包含name的项
+------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| last_name | varchar(15) | NO | | NULL | |
| first_name | varchar(15) | NO | | NULL | |
+------------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)
mysql> SHOW FIELDS FROM president like '%name'; # 查找名称中包含name的项，另外一种写法
+------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+-------------+------+-----+---------+-------+
| last_name | varchar(15) | NO | | NULL | |
| first_name | varchar(15) | NO | | NULL | |
+------------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)
插入数据
利用insert添加行
一次添加一行数据：
INSERT INTO president VALUES ('Washington','George',NULL,'Wakefield','VA','1732-02-22','1799-12-14');
INSERT INTO president VALUES ('Adams','John',NULL,'Braintree','MA','1735-10-30','1826-07-04');
一次添加多行数据：
INSERT INTO president VALUES ('Jefferson','Thomas',NULL,'Albemarle County','VA','1743-04-13','1826-07-04'), ('Madison','James',NULL,'Port Conway','VA','1751-03-16','1836-06-28');
利用文件添加新行
mysql> source insert_president.sql
Query OK, 0 rows affected (0.00 sec)
Query OK, 1 row affected (0.06 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.07 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.02 sec)
Query OK, 1 row affected (0.02 sec)
Query OK, 1 row affected (0.04 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.04 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.04 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.04 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.04 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.04 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.04 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.04 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.04 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.04 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.04 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.03 sec)
Query OK, 1 row affected (0.04 sec)
Query OK, 1 row affected (0.03 sec)
补充，文件source insert_president.sql内容如下：
DELETE FROM president;
INSERT INTO president VALUES ('Washington','George',NULL,'Wakefield','VA','1732-02-22','1799-12-14');
INSERT INTO president VALUES ('Adams','John',NULL,'Braintree','MA','1735-10-30','1826-07-04');
INSERT INTO president VALUES ('Jefferson','Thomas',NULL,'Albemarle County','VA','1743-04-13','1826-07-04');
INSERT INTO president VALUES ('Madison','James',NULL,'Port Conway','VA','1751-03-16','1836-06-28');
INSERT INTO president VALUES ('Monroe','James',NULL,'Westmoreland County','VA','1758-04-28','1831-07-04');
INSERT INTO president VALUES ('Adams','John Quincy',NULL,'Braintree','MA','1767-07-11','1848-02-23');
INSERT INTO president VALUES ('Jackson','Andrew',NULL,'Waxhaw settlement','SC','1767-03-15','1845-06-08');
INSERT INTO president VALUES ('Van Buren','Martin',NULL,'Kinderhook','NY','1782-12-05','1862-07-24');
INSERT INTO president VALUES ('Harrison','William H.',NULL,'Berkeley','VA','1773-02-09','1841-04-04');
INSERT INTO president VALUES ('Tyler','John',NULL,'Greenway','VA','1790-03-29','1862-01-18');
INSERT INTO president VALUES ('Polk','James K.',NULL,'Pineville','NC','1795-11-02','1849-06-15');
INSERT INTO president VALUES ('Taylor','Zachary',NULL,'Orange County','VA','1784-11-24','1850-07-09');
INSERT INTO president VALUES ('Fillmore','Millard',NULL,'Locke','NY','1800-01-07','1874-03-08');
INSERT INTO president VALUES ('Pierce','Franklin',NULL,'Hillsboro','NH','1804-11-23','1869-10-08');
INSERT INTO president VALUES ('Buchanan','James',NULL,'Mercersburg','PA','1791-04-23','1868-06-01');
INSERT INTO president VALUES ('Lincoln','Abraham',NULL,'Hodgenville','KY','1809-02-12','1865-04-15');
INSERT INTO president VALUES ('Johnson','Andrew',NULL,'Raleigh','NC','1808-12-29','1875-07-31');
INSERT INTO president VALUES ('Grant','Ulysses S.',NULL,'Point Pleasant','OH','1822-04-27','1885-07-23');
INSERT INTO president VALUES ('Hayes','Rutherford B.',NULL,'Delaware','OH','1822-10-04','1893-01-17');
INSERT INTO president VALUES ('Garfield','James A.',NULL,'Orange','OH','1831-11-19','1881-09-19');
INSERT INTO president VALUES ('Arthur','Chester A.',NULL,'Fairfield','VT','1829-10-05','1886-11-18');
INSERT INTO president VALUES ('Cleveland','Grover',NULL,'Caldwell','NJ','1837-03-18','1908-06-24');
INSERT INTO president VALUES ('Harrison','Benjamin',NULL,'North Bend','OH','1833-08-20','1901-03-13');
INSERT INTO president VALUES ('McKinley','William',NULL,'Niles','OH','1843-01-29','1901-09-14');
INSERT INTO president VALUES ('Roosevelt','Theodore',NULL,'New York','NY','1858-10-27','1919-01-06');
INSERT INTO president VALUES ('Taft','William H.',NULL,'Cincinnati','OH','1857-09-15','1930-03-08');
INSERT INTO president VALUES ('Wilson','Woodrow',NULL,'Staunton','VA','1856-12-19','1924-02-03');
INSERT INTO president VALUES ('Harding','Warren G.',NULL,'Blooming Grove','OH','1865-11-02','1923-08-02');
INSERT INTO president VALUES ('Coolidge','Calvin',NULL,'Plymouth Notch','VT','1872-07-04','1933-01-05');
INSERT INTO president VALUES ('Hoover','Herbert C.',NULL,'West Branch','IA','1874-08-10','1964-10-20');
INSERT INTO president VALUES ('Roosevelt','Franklin D.',NULL,'Hyde Park','NY','1882-01-30','1945-04-12');
INSERT INTO president VALUES ('Truman','Harry S',NULL,'Lamar','MO','1884-05-08','1972-12-26');
INSERT INTO president VALUES ('Eisenhower','Dwight D.',NULL,'Denison','TX','1890-10-14','1969-03-28');
INSERT INTO president VALUES ('Kennedy','John F.',NULL,'Brookline','MA','1917-05-29','1963-11-22');
INSERT INTO president VALUES ('Johnson','Lyndon B.',NULL,'Stonewall','TX','1908-08-27','1973-01-22');
INSERT INTO president VALUES ('Nixon','Richard M.',NULL,'Yorba Linda','CA','1913-01-09','1994-04-22');
INSERT INTO president VALUES ('Ford','Gerald R.',NULL,'Omaha','NE','1913-07-14','2006-12-26');
INSERT INTO president VALUES ('Carter','James E.','Jr.','Plains','GA','1924-10-01',NULL);
INSERT INTO president VALUES ('Reagan','Ronald W.',NULL,'Tampico','IL','1911-02-06','2004-06-05');
INSERT INTO president VALUES ('Bush','George H.W.',NULL,'Milton','MA','1924-06-12',NULL);
INSERT INTO president VALUES ('Clinton','William J.',NULL,'Hope','AR','1946-08-19',NULL);
INSERT INTO president VALUES ('Bush','George W.',NULL,'New Haven','CT','1946-07-06',NULL);
INSERT INTO president VALUES ('Obama','Barack H.',NULL,'Honolulu','HI','1961-08-04',NULL);
总结
登录
mysql -u root -p
本节SQL语句
mysql> SELECT NOW(); # 查询当前日期和时间，使用分号终止语句
mysql> SELECT NOW()g # 查询当前日期和时间，使用g终止语句
mysql> SELECT NOW(), USER(), VERSION()g # 查询时间，用户，系统版本，并在一列展示
mysql> SELECT NOW(), USER(), VERSION()G #查询时间，用户，系统版本，并在一行展示
mysql> SELECT NOW(); SELECT USER(); SELECT VERSION(); # 在一行输入多条语句
mysql> CREATE DATABASE sampdb; # 创建数据库
mysql> SELECT DATABASE(); # 查看当前数据库，结果为NULL
mysql> USE sampdb; # 把sampdb设置为当前默认选择的数据库
mysql> SELECT DATABASE(); # 查看当前数据库，结果为sampdb
mysql> source create_president.sql # 如果已经在终端cd到create_president.sql路径下，那么则可运行该语句
mysql> DESCRIBE president; # 查看president表的结构
mysql> DESC president; # DESCRIBE的简写为DESC
mysql> EXPLAIN president;
mysql> SHOW COLUMNS FROM president;
mysql> SHOW FIELDS FROM president;
mysql> SHOW FULL COLUMNS FROM president; # SHOW FULL COLUMNS 比 SHOW COLUMNS显示更多的信息
mysql> DESCRIBE president '%name'; # 查找名称中包含name的项
mysql> SHOW FIELDS FROM president like '%name'; # 查找名称中包含name的项，另外一种写法
mysql> INSERT INTO president VALUES ('Washington','George',NULL,'Wakefield','VA','1732-02-22','1799-12-14'); # 插入数据
mysql> INSERT INTO president VALUES ('Jefferson','Thomas',NULL,'Albemarle County','VA','1743-04-13','1826-07-04'), ('Madison','James',NULL,'Port Conway','VA','1751-03-16','1836-06-28'); # 一次添加多行数据
mysql> source insert_president.sql # 利用文件添加新行
待补充……