MySql技術內幕之MySQL入門(1)
目錄mysql
MySql技術內幕之MySQL入門(1)
安裝
檢查系統中是否已經安裝了MySQLsql
sudo netstat -tap | grep mysql
若沒有顯示已安裝結果，則沒有安裝。不然表示已經安裝。數據庫
sudo apt-get install mysql-server mysql-client
安裝過程當中會讓輸入密碼，記得把密碼記住。ubuntu
關於註釋
三種寫法：ide
- 用#單行註釋
- 用-- 單行註釋，注意後面有一空格
- /* */ 多行註釋
mysql> SELECT 1+1; # 這個註釋直到該行結束 mysql> SELECT 1+1; -- 這個註釋直到該行結束 mysql> SELECT 1 /* 這是一個在行中間的註釋 */ + 1; mysql> SELECT 1+ /* 這是一個 多行註釋的形式 */ 1;
執行SQL語句
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(); # 查詢當前日期和時間，使用分號終止語句
+---------------------+
| NOW() |
+---------------------+
| 2017-10-20 22:07:14 |
+---------------------+
1 row in set (0.00 sec)
mysql> SELECT NOW()\g # 查詢當前日期和時間，使用\g終止語句
+---------------------+
| NOW() |
+---------------------+
| 2017-10-20 22:07:56 |
+---------------------+
1 row in set (0.00 sec)
mysql> SELECT NOW(), USER(), VERSION()\g # 查詢時間，用戶，系統版本，並在一列展現
+---------------------+----------------+-------------------------+
| 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 #查詢時間，用戶，系統版本，並在一行展現
*************************** 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 # 在多行輸入
*************************** 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表示不執行上述語句
mysql> SELECT NOW(); SELECT USER(); SELECT VERSION(); # 在一行輸入多條語句
+---------------------+
| 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)
關於命令大小寫
通常用大寫字母表示SQL關鍵字和函數名；
用小寫字母表示數據庫，表和列的名字。函數
建立數據庫
mysql> CREATE DATABASE sampdb; # 建立數據庫 Query OK, 1 row affected (0.00 sec) mysql> SELECT DATABASE(); # 查看當前數據庫，結果爲NULL +------------+ | DATABASE() | +------------+ | NULL | +------------+ 1 row in set (0.00 sec) mysql> USE sampdb; # 把sampdb設置爲當前默認選擇的數據庫 Database changed mysql> SELECT DATABASE(); # 查看當前數據庫，結果爲NULL +------------+ | DATABASE() | +------------+ | sampdb | +------------+ 1 row in set (0.00 sec) mysql> source create_president.sql # 若是已經在終端cd到create_president.sql路徑下，那麼則可運行該語句 Query OK, 0 rows affected (0.15 sec) Query OK, 0 rows affected (0.23 sec)
補充，文件create_president.sql的內容以下：ui
# 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_
查看錶的信息
mysql> DESCRIBE president; # 查看president表的結構 +------------+-------------+------+-----+---------+-------+ | 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的簡寫爲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)
查看更加詳細的信息
mysql> SHOW FULL COLUMNS FROM president; # SHOW FULL COLUMNS 比 SHOW COLUMNS顯示更多的信息 +------------+-------------+-------------------+------+-----+---------+-------+---------------------------------+---------+ | 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)
查看與給定模式相匹配的列
若是須要對所查找的信息加以限定，code
mysql> DESCRIBE president '%name'; # 查找名稱中包含name的項 +------------+-------------+------+-----+---------+-------+ | 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'; # 查找名稱中包含name的項，另一種寫法 +------------+-------------+------+-----+---------+-------+ | 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)
插入數據
利用insert添加行
一次添加一行數據：server
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');
一次添加多行數據：ci
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)
補充，文件source insert_president.sql內容以下：
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);
總結
登陸
mysql -u root -p
本節SQL語句
mysql> SELECT NOW(); # 查詢當前日期和時間，使用分號終止語句
mysql> SELECT NOW()\g # 查詢當前日期和時間，使用\g終止語句
mysql> SELECT NOW(), USER(), VERSION()\g # 查詢時間，用戶，系統版本，並在一列展現
mysql> SELECT NOW(), USER(), VERSION()\G #查詢時間，用戶，系統版本，並在一行展現
mysql> SELECT NOW(); SELECT USER(); SELECT VERSION(); # 在一行輸入多條語句
mysql> CREATE DATABASE sampdb; # 建立數據庫
mysql> SELECT DATABASE(); # 查看當前數據庫，結果爲NULL
mysql> USE sampdb; # 把sampdb設置爲當前默認選擇的數據庫
mysql> SELECT DATABASE(); # 查看當前數據庫，結果爲sampdb
mysql> source create_president.sql # 若是已經在終端cd到create_president.sql路徑下，那麼則可運行該語句
mysql> DESCRIBE president; # 查看president表的結構
mysql> DESC president; # DESCRIBE的簡寫爲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顯示更多的信息
mysql> DESCRIBE president '%name'; # 查找名稱中包含name的項
mysql> SHOW FIELDS FROM president like '%name'; # 查找名稱中包含name的項，另一種寫法
mysql> INSERT INTO president VALUES ('Washington','George',NULL,'Wakefield','VA','1732-02-22','1799-12-14'); # 插入數據
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'); # 一次添加多行數據
mysql> source insert_president.sql # 利用文件添加新行
待補充……
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