# sql

## sql命令

[mysqldump详解](/linux/mysqldump-jiao-ben.md) 创建数据库：`CREATE DATABASE`activiti`DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci;` mysqldump:`mysqldump -hlocalhost -uadmin -P3308 -p123 --opt --single-transaction activiti` mysql导入:`mysql -hlocahost -P3310 -uroot -p1234 activiti < ./activiti.sql` 导出并导入:`mysqldump -h10.0.0.0 -uadmin -P9800 -p123456 --opt --single-transaction boss table1 table 2 | mysql -uroot -P8306 -p123456 -C boss`

## sql函数

### 时间函数

#### 时间增加间隔 date\_add()

[mysql 日期操作 增减天数、时间转换、时间戳 - 蚊子吃青蛙 - 博客园](https://www.cnblogs.com/wenzichiqingwa/archive/2013/03/05/2944485.html)

```sql
set @dt = now();
select date_add(@dt, interval 1 day);        -- add 1 day
select date_add(@dt, interval 1 hour);       -- add 1 hour
select date_add(@dt, interval 1 minute);     -- ...
select date_add(@dt, interval 1 second);
select date_add(@dt, interval 1 microsecond);
select date_add(@dt, interval 1 week);
select date_add(@dt, interval 1 month);
select date_add(@dt, interval 1 quarter);
select date_add(@dt, interval 1 year);
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://book.rizon.top/mysql/sql.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.