SQL常用语句和MySQl常用命令

  • 2019-08-23 09:58:23
  • Sun Xiaozhi
  • 156

SQL常用语句

  • 增加一张表
CREATE TABLE `table_name`(
  ...
)ENGINE=InnoDB DEFAULT CHARSET=utf8;
  • 增加记录
INSERT INTO `your_table_name`(`column_name`)
VALUES
('your_value_one'),
('your_value_two');
  • 增加字段
ALTER TABLE `your_table_name`
ADD `your_column_name` ...
AFTER `column_name`;
  • 增加索引
    • 主键 ALTER TABLE `your_table_name` ADD PRIMARY KEY your_index_name (your_column_name);
    • 唯一索引 ALTER TABLE `your_table_name` ADD UNIQUE your_index_name (your_column_name);
    • 普通索引 ALTER TABLE `your_table_name` ADD INDEX your_index_name (your_column_name);
    • 全文索引 ALTER TABLE `your_table_name` ADD FULLTEXT your_index_name (your_column_name);

  • 逐行删除
DELETE FORM `table_name` WHERE ...;
  • 清空整张表
TRUNCATE TABLE `your_table_name`;
  • 删除表
DROP TABLE `your_table_name`;
  • 删除字段
ALTER TABLE `your_table_name` DROP `column_name`;
  • 删除索引
ALTER TABLE `your_table_name` DROP INDEX your_index_name (your_column_name);

  • 变更数据
UPDATE `table_name`
SET column_name=your_value
WHERE ...;
  • 变更字段
ALTER TABLE `your_table_name`
CHANGE `your_column_name` `your_column_name` ...(变更);
  • 变更字段值为另一张表的某个值
UPDATE `your_table_name`
AS a
JOIN `your_anther_table_name`
AS b
SET a.column = b.anther_column
WHERE a.id = b.a_id...;

  • 普通查询
SELECT `column_name_one`, `column_name_two` FROM `table_name`;
  • 关联查询
SELECT *
FROM `your_table_name`
AS a
JOIN `your_anther_table_name`
AS b
WHERE a.column_name = b.column_name...;
  • 合计函数条件查询:WHERE 关键字无法与合计函数一起使用
SELECT aggregate_function(column_name)
FROM your_table_name
GROUP BY column_name
HAVING aggregate_function(column_name)...;
  • 同一个实例下跨库查询
SELECT *
FROM database_name.your_table_name
AS a
JOIN another_database_name.your_another_table_name
AS b
WHERE a.column_name = b.column_name...;

复制一张表结构

CREATE TABLE `your_table_name` LIKE `destination_table_name`;

完全复制一张表:表结构+全部数据

CREATE TABLE `your_table_name` LIKE `destination_table_name`;

INSERT INTO `your_table_name` SELECT
    *
FROM
    `destination_table_name`;

MySQL常用命令

  • 登陆: mysql -h host -u username -p
  • 列出数据库:SHOW DATABESES;
  • 列出表:SHOW TABLES;
  • 列出表结构:DESC table_name
  • 使用一个数据库:USE database_name;
  • 导入:source ‘file’;
  • 导出:mysqldump -h 127.0.0.1 -u root -p “database_name” “table_name” –where=”condition” > file_name.sql;
  • 查看慢日志:mysqldumpslow -s [c:按记录次数排序/t:时间/l:锁定时间/r:返回的记录数] -t [n:前n条数据] -g “正则” /path
  • 新增用户: insert into user(Host, User, authentication_string) value(‘localhost’, ‘username’, password(‘pwd’))

mysql 5.7 新增用户

// 插入新用户
insert into mysql.user(Host, User, authentication_string, ssl_cipher, x509_issuer, x509_subject
value('localhost', 'username', password('password'), '', '', '');

// 数据库授权
grant all privileges on dbname.name.* to username@localhost identified by 'password';

// 刷新权限信息
FLUSH PRIVILEGES;

mysql如何开启远程连接

GRANT ALL PRIVILEGES ON . TO 'root'@'%' IDENTIFIED BY 'root' WITH GRANT OPTION;
flush privileges;

ORDER BY排序

f1用升序,f2降序,sql该这样写

ORDER BY f1, f2 DESC

也可以这样写,更清楚:

ORDER BY f1 ASC, f2 DESC

如果都用降序,必须用两个desc

ORDER BY f1 DESC, f2 DESC