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This article mainly introduces how to use the if tag in mybatis, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let Xiaobian take you to understand it.

Mybatis tags are widely used in project development. This article explains two ways of using if tags.

First, use the label to determine whether a field is empty or not

Second, use tags to determine whether the incoming parameters are equal.

The specific code is as follows

Database table structure and data

Entity class

Package com.demo.bean; public class Commodity {private String name;private String date; public String getName () {return name;} public void setName (String name) {this.name = name;} public String getDate () {return date;} public void setDate (String date) {this.date = date;} @ Overridepublic String toString () {return "Com [name=" + name + ", date=" + date + "]";}}

Mapper layer

Package com.demo.mapper; import java.util.List;import org.apache.ibatis.annotations.Mapper;import org.apache.ibatis.annotations.Param;import com.demo.bean.Commodity;@Mapperpublic interface CommodityMapper {List getListByDate (Commodity commodity); List getListByStartDateAndEndDate (@ Param ("startDate") String startDate, @ Param ("endDate") String endDate;}

Mapper.xml file

Select * from commodity where 1 = 1 and date = # {date} select * from commodity where 1 = 1 and date between # {startDate} and # {endDate}

Note: the tostring () method of mybatis equivalence judgment (the toString () method in the second select in the above code)

Controller layer

Package com.demo.controller; import java.util.HashMap;import java.util.Map;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.ResponseBody;import org.springframework.web.bind.annotation.RestController;import com.demo.bean.Commodity;import com.demo.mapper.CommodityMapper; @ RestControllerpublic class DemoController {@ Autowiredprivate CommodityMapper comMapper;@RequestMapping (value = "/ commodity") public Object commodity () {Map map = new HashMap () Commodity com = new Commodity (); com.setDate ("2018-10-12"); map.put ("res", comMapper.getListByDate (com)); return map;} @ RequestMapping (value = "/ between") public Object commodityBetween () {Map map = new HashMap (); map.put ("res", comMapper.getListByStartDateAndEndDate ("2018-10-09", "2018-10-13")); return map;}}

test

1. Visit http://localhost:9000/commodity

2. Visit http://localhost:9000/between

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