目录

一、什么是动态SQL

 二、动态SQL用法

 三、模糊查询

sql语句根据条件而发生改变。

 二、动态SQL用法

以题为例

CREATE TABLE `student` ( `s_id` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL, `s_name` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL DEFAULT '', `s_birth` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL DEFAULT '', `s_sex` varchar(10) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci NOT NULL DEFAULT '', PRIMARY KEY (`s_id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8

 测试类

import com.exy.dao.StudentDao;
import com.exy.entity.Student;
import com.github.pagehelper.PageHelper;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.Before;
import org.junit.Test;

import java.io.Reader;
import java.util.HashMap;
import java.util.List;
import java.util.Map;



public class STest {
    private SqlSession session;
    @Before
    public void before() throws Exception{
        Reader reader = Resources.getResourceAsReader("mybatis.xml");
        SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(reader);
        session=sessionFactory.openSession();
    }

    @Test
    public void test() throws Exception{
        StudentDao studentDao = session.getMapper(StudentDao.class);
        PageHelper.startPage(0,2);
        List list = studentDao.selectAll();
        System.out.println(list);
    }
    @Test
    public void test01() throws Exception{
        StudentDao studentDao = session.getMapper(StudentDao.class);
        Map map=new HashMap();
        map.put("name","");
        map.put("sex","女");
        List list = studentDao.selectna(map);
        System.out.println(list);
    }
    @Test
    public void test02() throws Exception{
        StudentDao studentDao = session.getMapper(StudentDao.class);
        Student student = new Student(01,"赵雷","1999","女");
        int list = studentDao.update(student);
        session.commit();
        System.out.println(list);
    }
    @Test
    public void test03() throws Exception{
        StudentDao studentDao = session.getMapper(StudentDao.class);
        Map map=new HashMap();
        map.put("name","赵雷");
        map.put("sex","女");
        List list = studentDao.selectns(map);
        System.out.println(list);
    }
    @Test
    public void test04(){
        StudentDao studentDao = session.getMapper(StudentDao.class);
        int [] ids ={01,02,03};
        List list = studentDao.selectid(ids);
        System.out.println(list);
    }
    @Test
    public void test05() throws Exception{
        StudentDao studentDao = session.getMapper(StudentDao.class);
        List list = studentDao.selectlike("雷");
        System.out.println(list);
    }
    
}

 

 第一题

 

 

 第二题

 第三题

第四题

 代码块

    
        select * from student
    


    
        select * from student where s_name like concat('%',#{s_name},'%')
    

    
        select * from student
        
            
                
                    and s_name=#{name}
                
                
                    and s_sex=#{sex}
                
                

                
            
        

    

    
        update student
        
            
                s_name=#{s_name},
            
            
                s_birth=#{s_birth},
            
            
                s_sex=#{s_sex},
            

        
        where s_id=#{s_id}
    


    
        select * from student
        
            
                
                    and s_name=#{name}
                
                
                    and s_sex=#{sex}
                
            
        

    

    
        select * from student where s_id in
        
            #{s_id}
        
    

 三、模糊查询

根据部分值得出全部like和%配合