1.一體化:SQL集數據定義DDL、數據操縱DML和數據控制DCL於一體,可以完成數據庫中的全部工作。
2.使用方式靈活:它具有兩種使用方式,即可以直接以命令方式交互使用;也可以嵌入使用,嵌入到C、C++、FORTRAN、COBOL、JAVA等主語言中使用。
3.非過程化:只提操作要求,不必描述操作步驟,也不需要導航。使用時只需要告訴計算機“做什麼”,而不需要告訴它“怎麼做”。
4.語言簡潔,語法簡單,好學好用:在ANSI標準中,只包含了94個英文單詞,核心功能只用6個動詞,語法接近英語口語。
1 2 3 4 5 6 | CHAR(n) : 定長字符 VARCHAR(n) :可變長字符 BINARY(n) :二進制字符 VARBINARY(n) :可變長二進制字符 TEXT :文本型數據 BLOB :二進制大對象 |
1 2 3 4 5 | TINYINT: 1byte, -128, 127 0,255 微整形 SMALLINIT: 2bytes, -32768, 32767 0,65535 小整形 MEDIUMINT: 3bytes, 0,2^24 中整形 INT: 4bytes, 0,2^32 整型 BIGINT: 8bytes, 0,2^64 大整型 |
1 2 3 | FLOAT 單精度 DOUBLE 雙精度 REAL |
1 2 3 4 5 | DATE TIME DATETIME YEAR(2), YEAR(4) TIMESTAMP |
1 | ENUM, SET |
1 | mysql> show [global|session] variables; |
1 | mysql> show [global|session] status; |
1 | mysql> SHOW CHARACTER SET; |
1 | mysql> SHOW COLLATION; |
1 | mysql> SELECT VERSION(); |
1 | mysql> SHOW DATABASES; |
1 | mysql> SELECT DATABASE(); |
1 | mysql> CREATE DATABASE DB_NAME; |
1 | mysql> DROP DATABASE DB_NAME; |
1 2 | mysql OPTIONS < script.sql mysql> source /path/to/script .sql |
1 | mysql>CREATE USER username@host [IDENTIFIED BY 'password' ]; |
1 | mysql>GRANT ALL PRIVILEGES ON dbname.tablename TO username@host [IDENTIFIED BY 'password' ]; |
1 | mysql> SET PASSWORD FOR username@host=PASSWORD( 'password' ); |
1 | mysql>DROP USER username@host; |
1 | mysql>CREATE TABLE tb_name (col1 defination, col2 defination, ..., key defination); |
1 | mysql>DROP TABLE tb_name; |
1 | mysql> INSERT INTO 表 字段 VALUES; |
1 | mysql> UPDATE 表名 SET 字段名=值 WHERE; |
1 | mysql> DELETE FROM 表名 WHERE 條件 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | mysql> CREATE DATABASE mytestdb use mytestdb myaql> CREATE TABLE students (ID TINYINT UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT,
Name CHAR(30) NOT NULL UNIQUE KEY,
Age TINYINT UNSIGNED, Gender CHAR(1) DEFAULT 'M' ,
Course VARCHAR(50) NOT NULL); mysql> INSERT students (Name,Age,Gender,Course)VALUES( 'Ling Huchong' ,24, 'M' , 'Hamogong' ),
( 'Huang Rong' ,19, 'F' , 'Chilian Shenzhang' ),
( 'Lu Wushuang' ,18, 'F' , 'Jiuying Shengong' ),
( 'Zhu Ziliu' ,52, 'M' , 'Pixie Jianfa' ),
( 'Chen Jialuo' ,22, 'M' , 'Xianglong Shiba Zhang' ); mysql> SELECT name FROM students WHERE Gender= 'Female' ; mysql> SELECT name FROM students WHERE Age>20; mysql> UPDATE students SET Course= 'Kuihua Baodian' WHERE name= 'Zhu Ziliu' ; mysql> DELETE FROM students WHERE Age<=19; mysql> GRANT ALL ON testdb.* TO 'testuser' @ '%' ; |