正确结果
xml
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.itheima.mapper.BrandMapper">
<!-- 完成数据库表和Java代码的映射 -->
<resultMap id="BrandResultMap" type="brand">
<result column="brand_name" property="brandName"></result>
<result column="company_name" property="companyName"></result>
</resultMap>
<select id="selectByConditionSingle" resultMap="BrandResultMap">
select *
from tb_brand
where
<choose><!--相当于switch-->
<when test="status != null"><!--相当于case-->
status = #{status}
</when>
<when test="companyName != null and companyName != '' "><!--相当于case-->
company_name like #{companyName}
</when>
<when test="brandName != null and brandName != ''"><!--相当于case-->
brand_name like #{brandName}
</when>
<otherwise>
1 = 1
</otherwise>
</choose>
</select>
</mapper>
由于使用Brand对象传参,此时使用标签,没有给Brand对象赋值,此时应该查询数据库的三条记录
但是,如果因为实体类的变量数据类型为基本类型,而不是它的包装类型,可能会出现如下错误
此时,status的默认值就会变为0,达不到预期的效果
下方为正确的实体类代码
java
package com.itheima.pojo;
/**
* @package: com.itheima.pojo
* @className: Brand
* @Description:
* @author: haozihua
* @date: 2024/11/8 10:32
*/
public class Brand {
private Integer id;
private String brandName;
private String companyName;
private Integer ordered;
private String description;
private Integer status;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getBrandName() {
return brandName;
}
public void setBrandName(String brandName) {
this.brandName = brandName;
}
public String getCompanyName() {
return companyName;
}
public void setCompanyName(String companyName) {
this.companyName = companyName;
}
public Integer getOrdered() {
return ordered;
}
public void setOrdered(Integer ordered) {
this.ordered = ordered;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public Integer getStatus() {
return status;
}
public void setStatus(Integer status) {
this.status = status;
}
@Override
public String toString() {
return "Brand{" +
"id=" + id +
", brandName='" + brandName + '\'' +
", companyName='" + companyName + '\'' +
", ordered=" + ordered +
", description='" + description + '\'' +
", status=" + status +
'}';
}
}