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数据库的关键字大小写无所谓,为了方便学习,这里的关键字我用大写来区分。
CREATE DATABASE database_name
DROP DATABASE database_name
USE database_name
CREATE TABLE table_name (column_name column_type)
例子:
CREATE TABLE IF NOT EXISTS demo ( id INT UNSIGNED AUTO_INCREMENT, title VARCHAR(100) NOT NULL, PRIMARY KEY (id) ) ENGINE=innoDB DEFAULT CHARSET=utf8
DROP TABLE table_name
INSERT INTO table_name (field1, field2, ...fieldN) VALUES (value1, value2, ...value3)
INSERT INTO demo (title) VALUES ('标题')
SELECT column_name1, column_name2 FROM table_name [WHERE Clause] [LIMIT N][ OFFSET M]
SELECT field1, field2, ...fieldN FROM table_name1, table_name2 ... [WHERE condition1 [AND [OR]]] condition2 ...
UPDATE table_name SET field1=new-value1, field2=new-value2 [WHERE Clause]
DELETE FROM table_name [WHERE Clause]
SELECT field1, field2, ...fieldN FROM table_name WHERE field1 LIKE condition1 [AND [OR]] field2 = 'somevalue'
SELECT expression1, expression2, ...expression_n FROM table_name [WHERE condition] UNION [ALL | DISTINCT] SELECT expression1, expression2, ...expression_n FROM another_table_name [WHERE condition]
SELECT field1, field, ...fieldN FROM table_name1, table_name2 ... ORDER BY field1 [ASC [DESC][默认 ASC]], [field2...][ASC [DESC][默认 ASC]]
SELECT column_name, function(column_name) FROM table_name WHERE column_name operator value GROUP BY column_name
可以使用JOIN进行联合多表查询。
JOIN
LEFT JOIN
为了处理NULL值,MYSQL提供了三大运算符:
NULL
MYSQL
IS NULL:当列的值是NULL,此运算符返回true
true
IS NOT NULL:当列的值不为NULL,此运算符返回true
<=>:比较操作符(不同于 = 运算符),当比较的两个值相等或者都为NULL时返回true
关键字REGEXP
REGEXP
MYSQL事务主要用来处理操作量打,复杂度高得数据。
一般来说,事务是必须满足4个条件ACID:
原子性(Atomicity)
一致性(Consistency)
隔离性(Isolation)
持久性(Durability)
本汇总分两篇完成,下篇再见。
The text was updated successfully, but these errors were encountered:
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数据库的关键字大小写无所谓,为了方便学习,这里的关键字我用大写来区分。
创建数据库
删除数据库
选择数据库
创建数据表
例子:
删除数据表
插入数据
例子:
INSERT INTO demo (title) VALUES ('标题')
查询数据
WHERE子句
UPDATE更新
DELETE语句
LIKE子句
UNION
SELECT expression1, expression2, ...expression_n FROM table_name [WHERE condition] UNION [ALL | DISTINCT] SELECT expression1, expression2, ...expression_n FROM another_table_name [WHERE condition]
排序
分组
连接
可以使用
JOIN
进行联合多表查询。LEFT JOIN
相反,用于获取右表所有记录,即使左表没有对应匹配的记录NULL值处理
为了处理
NULL
值,MYSQL
提供了三大运算符:IS NULL:当列的值是
NULL
,此运算符返回true
IS NOT NULL:当列的值不为
NULL
,此运算符返回true
<=>:比较操作符(不同于 = 运算符),当比较的两个值相等或者都为
NULL
时返回true
正则
关键字
REGEXP
事务
MYSQL
事务主要用来处理操作量打,复杂度高得数据。一般来说,事务是必须满足4个条件ACID:
原子性(Atomicity)
一致性(Consistency)
隔离性(Isolation)
持久性(Durability)
本汇总分两篇完成,下篇再见。
The text was updated successfully, but these errors were encountered: