第八讲 动态SQL

一、动态SQL指根据不同的查询条件，生成不同的SQL语句

二、mapper映射文件（别忘了引入到mybatis-config.xml中）

<?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.liujie.model.UserMapper">

     <select id="getUserByCondition" parameterType="Map" resultType="User">

           select * from user

           <where>

                <if test="name != null">

                     name like CONCAT('%', #{name}, '%')

                </if>

           </where>

     </select>

</mapper>

<?xml version="1.0" encoding="UTF-8" ?>

<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN"

"http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>

     <properties resource="db.properties"></properties>

     

     <typeAliases>

           <package name="com.liujie.model"/>

     </typeAliases>

     

     <environments default="development">

           <environment id="development">

                <transactionManager type="JDBC" />

                <dataSource type="POOLED">

                     <property name="driver" value="${driver}" />

                     <property name="url" value="${url}" />

                     <property name="username" value="${username}" />

                     <property name="password" value="${password}" />

                </dataSource>

           </environment>

     </environments>

     <mappers>

           <mapper resource="com/liujie/model/user.mapper.xml"/>

     </mappers>

</configuration>

1

三、测试

public class UserDao {

     

     public List<User> getAll(Map<String, Object> map) throws IOException {

           SqlSession session = MyBatisUtil.getSqlSession();

           List<User> list = session.selectList("com.liujie.model.UserMapper.getUserByCondition", map);

           session.close();

           return list;

     }

     

}

public class Test {

     

     public static void main(String[] args) throws IOException {

           

           UserDao userDao = new UserDao();

           Map<String, Object> map =new HashMap<String, Object>();

           map.put("name", "李亚东");

           List<User> list = userDao.getAll(map);

           for(User user : list) {

                System.out.println(user);

           }

     }

     

}