select advert.id as id, advert.advert_no as advertNo, advert.title, advert.advert_type as advertType, advert.advert_position as advertPosition, advert.advert_url as advertUrl, advert.start_time as startTime, advert.end_time as endTime, advert.create_time as createTime, ua.nick_name as createdByName , if(NOW()>advert.start_time,1,if(NOW()<advert.start_time),2,3) AS zhuangtai from ( select ja.id,ja.advert_no, ja.title, ja.advert_type,ja.advert_position,ja.advert_url, ja.start_time, ja.end_time, ja.created_by, ja.create_time from job_advert ja where ja.is_delete = 0 order by ja.create_time desc )advert LEFT JOIN ums_admin ua on advert.created_by = ua.id order by advert.id desc 这段sql有什么语法问题
时间: 2024-02-14 14:08:46 浏览: 19
从语法上看,这段 SQL 语句中有一个语法错误:
```
if(NOW()>advert.start_time,1,if(NOW()<advert.start_time),2,3) AS zhuangtai
```
应该修改为:
```
IF(NOW() > advert.start_time, 1, IF(NOW() < advert.end_time, 2, 3)) AS zhuangtai
```
修改后的语句中,使用了 MySQL 的 IF 函数,来判断当前时间和广告的开始时间、结束时间的关系,从而返回对应的状态。同时,将 SQL 函数名改为了大写字母,以符合 MySQL 的语法规范。
相关问题
<select id="findAdverts" resultMap="advertMap"> SELECT a.*, p.id AS position_id, p.name AS position_name, m.id AS media_id, m.file_name, m.file_type, m.file_url FROM advert a LEFT JOIN ad_position p ON a.position_id = p.id LEFT JOIN media_file m ON a.media_id = m.id WHERE (id = :id OR :id IS NULL) </select>是否正确
这个 SQL 语句是正确的,它查询了 `advert` 表、`ad_position` 表和 `media_file` 表,使用了 `LEFT JOIN` 进行了关联查询。条件语句 `(id = :id OR :id IS NULL)` 判断了是否传入了 ID 参数,如果传入了,则只查询 ID 对应的数据,如果没有传入,则查询全部数据。
需要注意的是,`resultMap` 属性指定了查询结果的映射方式,需要在相应的 resultMap 中定义 `advertMap`。同时,作为一个符合规范的 SQL 语句,它还需要在 `<mapper>` 标签中定义 `namespace` 属性,指定该 SQL 语句所属的命名空间,如下所示:
```xml
<mapper namespace="com.example.mapper.AdvertMapper">
<resultMap id="advertMap" type="Advert">
<!-- 定义查询结果与实体类的映射关系 -->
</resultMap>
<select id="findAdverts" resultMap="advertMap">
SELECT a.*, p.id AS position_id, p.name AS position_name, m.id AS media_id, m.file_name, m.file_type, m.file_url
FROM advert a
LEFT JOIN ad_position p ON a.position_id = p.id
LEFT JOIN media_file m ON a.media_id = m.id
WHERE (id = :id OR :id IS NULL)
</select>
</mapper>
```
SELECT a.*, p.id AS position_id, p.name AS position_name, m.id AS media_id, m.file_name, m.file_type, m.file_url FROM advert a LEFT JOIN ad_position p ON a.position_id = p.id LEFT JOIN media_file m ON a.media_id = m.id WHERE (id = :id OR :id IS NULL)如果要这些sql语句,springboot需要引入什么依赖?
为了使用 MyBatis 来执行这个 SQL 查询语句,需要在 Spring Boot 项目中引入以下依赖:
1. mybatis-spring-boot-starter:MyBatis 的 Spring Boot Starter,包含了 MyBatis 的核心库和与 Spring Boot 集成的必要组件。
2. mysql-connector-java:MySQL 数据库的 JDBC 驱动,用于连接 MySQL 数据库。
这两个依赖可以在 Maven 或 Gradle 中进行配置,例如在 Maven 中可以添加以下依赖:
```xml
<dependencies>
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.2.0</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.26</version>
</dependency>
</dependencies>
```
配置好依赖后,需要在 Spring Boot 的配置文件中配置 MyBatis 的相关参数,例如数据源、Mapper 接口等。