EmployeeMapperDynamicSql.java
package com.gong.mybatis.mapper; import java.util.List; java.util.Map; org.apache.ibatis.annotations.MapKey; com.gong.mybatis.bean.Employee; public interface EmployeeMapperDynamicSql { public List<Employee> getEmpByConditionIf(Employee employee); void updateEmp(Employee employee); }
EmployeeMapperDynamicSql.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.gong.mybatis.mapper.EmployeeMapperDynamicSql"> <!-- 查询,要查那个就带上那个条件 --> select id="getEmpByConditionIf" resultType="com.gong.mybatis.bean.Employee"> select * from tbl_employee where> choose> when test="id!=null" id=#{id} </when="lastName!=null" last_name like #{lastName} ="email!=null" email=#{email} otherwise> select> update ="updateEmp" update tbl_employee set if last_name=#{lastName},if="gender!=null and gender == 0 or gender == 1" gender=#{gender},1)"> email=#{email} where id=#{id} update> mapper>
结合之前的知识,我们在这里不使用set标签:
进行测试:
com.gong.mybatis.test; java.io.IOException; java.io.InputStream; org.apache.ibatis.io.Resources; org.apache.ibatis.session.SqlSession; org.apache.ibatis.session.SqlSessionFactory; org.apache.ibatis.session.SqlSessionFactoryBuilder; org.junit.Test; com.gong.mybatis.bean.Employee; com.gong.mybatis.mapper.EmployeeMapperDynamicSql; class TestMybatis3 { public SqlSessionFactory getSqlSessionFactory() throws IOException { String resource = "mybatis-config.xml"; InputStream is = Resources.getResourceAsStream(resource); return new SqlSessionFactoryBuilder().build(is); } @Test void test() IOException { SqlSessionFactory sqlSessionFactory = getSqlSessionFactory(); SqlSession openSession = sqlSessionFactory.openSession(); try { EmployeeMapperDynamicSql mapper = openSession.getMapper(EmployeeMapperDynamicSql.); Employee employee = Employee(); employee.setId(1); employee.setLastName("hanbin"); // employee.setGender("0"); employee.setEmail("dema@qq.com"); mapper.updateEmp(employee); List<Employee> es = mapper.getEmpByConditionIf( Employee()); for(Employee e:es) { System.err.println(e); } openSession.commit(); } finally { openSession.close(); } } }
我们先对Id=1的记录修改last_name=hanbin,结果:会报错,因为sql最后面多了个逗号
DEBUG 01-21 14:31:18,323 ==> Preparing: update tbl_employee set last_name=?, where id=? (BaseJdbcLogger.java:145)
DEBUG 01-21 14:31:18,366 ==> Parameters: hanbin(String),1(Integer) (BaseJdbcLogger.java:145)
解决方法有两种:
第一种:使用set标签,会自动过滤掉多余的逗号
update tbl_employee set last_name=#{lastName},1)"> gender=#{gender},1)"> email=#{email} >
结果:
DEBUG 01-21 14:46:11,726 ==> Preparing: select * from tbl_employee (BaseJdbcLogger.java:145) DEBUG 01-21 14:46:11,727 ==> Parameters: (BaseJdbcLogger.java:145) DEBUG 01-21 14:46:11,756 == Total: 4 (BaseJdbcLogger.java:145) Employee [id=1,lastName=hanbin,1)">gender=0,1)">email=hanbin@qq.com,1)">dept=null]
第二种:使用之前学过的trim标签
trim prefix="set" suffixOverrides=","trim>
并修改id=1的last_name为dema,gender为1,email为dema@qq.com
employee.setId(1);
employee.setLastName("dema");
employee.setGender("1");
employee.setEmail("dema@qq.com");
结果:
DEBUG 01-21 14:53:38,851 ==> Preparing: select * from tbl_employee (BaseJdbcLogger.java:145) DEBUG 01-21 14:53:38,852 ==> Parameters: (BaseJdbcLogger.java:145) DEBUG 01-21 14:53:38,885 =dema,1)">=dema@qq.com,1)">=null] Employee [id=2,1)">=jack,1)">=675544321@qq.com,1)">=3,1)">=小红,1)">=xiaohong@qq.com,1)">=4,1)">=小明,1)">=xiaoming@qq.com,1)">=null]