mybatis(4)動態sql

mybatis.xml，db.properties,MybatisUtil.java,student.java和第一篇文章一樣,所建的表也是一樣的

動態SQL操作之查詢

StudentDao.java

/**
 * 持久層 
 * @author AdminTC
 */
public class StudentDao {
	/**
	 * 有條件的查詢所有學生
	 */
	public List<Student> findAll(Integer id,String name,Double sal) throws Exception{
		SqlSession sqlSession = null;
		try{
			sqlSession = MybatisUtil.getSqlSession();
				
			Map<String,Object> map = new LinkedHashMap<String,Object>();
			map.put("pid",id);
			map.put("pname",name);
			map.put("psal",sal);
			
			return sqlSession.selectList("studentNamespace.findAll",map);
		}catch(Exception e){
			e.printStackTrace();
			throw e;
		}finally{
			MybatisUtil.closeSqlSession();
		}
	}

	
	public static void main(String[] args) throws Exception{
		StudentDao dao = new StudentDao();
		List<Student> studentList = dao.findAll(5,"哈哈",7000D);
		for(Student s : studentList){
			System.out.println(s.getId()+":"+s.getName()+":"+s.getSal());
		}
	}
}

StudentMapper.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="studentNamespace">	

	<resultMap type="cn.itcast.javaee.mybatis.app11.Student" id="studentMap">
		<id property="id" column="students_id"/>
		<result property="name" column="students_name"/>
		<result property="sal" column="students_sal"/>
	</resultMap>


	
	<select id="findAll" parameterType="map" resultMap="studentMap">
		select * from students
		<where>
			<if test="pid!=null">
				and students_id = #{pid}
			</if>
			<if test="pname!=null">
				and students_name = #{pname}
			</if>
			<if test="psal!=null">
				and students_sal = #{psal}
			</if>
		</where>
	</select>
	
</mapper>

動態SQL操作之更新

StudentDao.java

/**
 * 持久層 
 * @author AdminTC
 */
public class StudentDao {
	/**
	 * 有條件更新學生
	 */
	public void dynaUpdate(Integer id,String name,Double sal) throws Exception{
		SqlSession sqlSession = null;
		try{
			sqlSession = MybatisUtil.getSqlSession();
				
			Map<String,Object> map = new HashMap<String, Object>();
			map.put("pid",id);
			map.put("pname",name);
			map.put("psal",sal);
			sqlSession.update("studentNamespace.dynaUpdate",map);
			sqlSession.commit();
		}catch(Exception e){
			e.printStackTrace();
			sqlSession.rollback();
			throw e;
		}finally{
			MybatisUtil.closeSqlSession();
		}
	}
	
		public static void main(String[] args) throws Exception{
		StudentDao dao = new StudentDao();
		//關注SQL的變化
		//dao.dynaUpdate(1,null,9000D);//update students set sal=? where id=?
		//dao.dynaUpdate(1,"笨笨",null);//update students set name=? where id=?
		dao.dynaUpdate(1,"笨笨",10000D);//update students set name=? and sal=? where id=?
	}
}

StudentMapper.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="studentNamespace">	

	<resultMap type="cn.itcast.javaee.mybatis.app12.Student" id="studentMap">
		<id property="id" column="students_id"/>
		<result property="name" column="students_name"/>
		<result property="sal" column="students_sal"/>
	</resultMap>

	<!-- set標籤自動判斷哪個是最後一個字段，會自動去掉最後一個,號 -->
	<update id="dynaUpdate" parameterType="map">
		update students 
		<set>
			<if test="pname!=null">
				students_name = #{pname},
			</if>
			<if test="psal!=null">
				students_sal = #{psal},			
			</if>
		</set>
		where students_id = #{pid}
	</update>
	
	
</mapper>

動態SQL操作之刪除
StudentDao.java

/**
 * 持久層 
 * @author AdminTC
 */
public class StudentDao {
	/**
	 * 根據ID批量刪除學生(數組版本)
	 */
	public void dynaDeleteArray(int... ids) throws Exception{
		SqlSession sqlSession = null;
		try{
			sqlSession = MybatisUtil.getSqlSession();
			sqlSession.delete("studentNamespace.dynaDeleteArray",ids);
			sqlSession.commit();
		}catch(Exception e){
			e.printStackTrace();
			sqlSession.rollback();
			throw e;
		}finally{
			MybatisUtil.closeSqlSession();
		}
	}
	/**
	 * 根據ID批量刪除學生(集合版本)
	 */
	public void dynaDeleteList(List<Integer> ids) throws Exception{
		SqlSession sqlSession = null;
		try{
			sqlSession = MybatisUtil.getSqlSession();
			sqlSession.delete("studentNamespace.dynaDeleteList",ids);
			sqlSession.commit();
		}catch(Exception e){
			e.printStackTrace();
			sqlSession.rollback();
			throw e;
		}finally{
			MybatisUtil.closeSqlSession();
		}
	}
	
	public static void main(String[] args) throws Exception{
		StudentDao dao = new StudentDao();
		//dao.dynaDeleteArray(new int[]{1,3,5,7,77});
		//dao.dynaDeleteArray(1,3,5,7,77);
		//dao.dynaDeleteArray(2,4,444);
		
		List<Integer> ids = new ArrayList<Integer>();
		ids.add(6);
		ids.add(8);
		ids.add(9);
		dao.dynaDeleteList(ids);
	}
}

StudentMapper.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="studentNamespace">	

	<resultMap type="cn.itcast.javaee.mybatis.app13.Student" id="studentMap">
		<id property="id" column="students_id"/>
		<result property="name" column="students_name"/>
		<result property="sal" column="students_sal"/>
	</resultMap>

	
	
	<delete id="dynaDeleteArray">
		delete from students where students_id in
		<!-- foreach用於迭代數組元素
			 open表示開始符號
			 close表示結束符合
			 separator表示元素間的分隔符
			 item表示迭代的數組，屬性值可以任意，但提倡與方法的數組名相同
			 #{ids}表示數組中的每個元素值
		 -->
		<foreach collection="array" open="(" close=")" separator="," item="ids">
			#{ids}
		</foreach>
	</delete>
	
	
	
	
	<delete id="dynaDeleteList">
		delete from students where students_id in
		<foreach collection="list" open="(" close=")" separator="," item="ids">
			#{ids}
		</foreach>
	</delete>
	
	
	
</mapper>

動態SQL操作之插入
StudentDao.java

/**
 * 持久層 
 * @author AdminTC
 */
public class StudentDao {
	/**
	 * 插入學生
	 */
	public void dynaInsert(Student student) throws Exception{
		SqlSession sqlSession = null;
		try{
			sqlSession = MybatisUtil.getSqlSession();
			sqlSession.insert("studentNamespace.dynaInsert",student);
			sqlSession.commit();
		}catch(Exception e){
			e.printStackTrace();
			sqlSession.rollback();
			throw e;
		}finally{
			MybatisUtil.closeSqlSession();
		}
	}
	
	public static void main(String[] args) throws Exception{
		StudentDao dao = new StudentDao();
		//dao.dynaInsert(new Student(1,"哈哈",7000D));//insert into 表名(*,*,*) values(?,?,?)
		//dao.dynaInsert(new Student(2,"哈哈",null));//insert into 表名(*,*) values(?,?)
		//dao.dynaInsert(new Student(3,null,7000D));//insert into 表名(*,*) values(?,?)
		dao.dynaInsert(new Student(4,null,null));//insert into 表名(*) values(?)
	}
}

StudentMapper.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="studentNamespace">	

	<resultMap type="cn.itcast.javaee.mybatis.app14.Student" id="studentMap">
		<id property="id" column="students_id"/>
		<result property="name" column="students_name"/>
		<result property="sal" column="students_sal"/>
	</resultMap>

	
	<!-- sql片段對應字段名,id屬性值任意 -->
	<sql id="key">
		<!-- 去掉最後一個, -->
		<trim suffixOverrides=",">
			<if test="id!=null">
				students_id,
			</if>
			<if test="name!=null">
				students_name,
			</if>
			<if test="sal!=null">
				students_sal,
			</if>
		</trim>
	</sql>
	
	
	<!-- sql片段對應?,id屬性值任意 -->
	<sql id="value">
		<!-- 去掉最後一個, -->
		<trim suffixOverrides=",">
			<if test="id!=null">
				#{id},
			</if>
			<if test="name!=null">
				#{name},
			</if>
			<if test="sal!=null">
				#{sal},
			</if>
		</trim>
	</sql>
	
	
	<!-- <include refid="key"/>和<include refid="value"/>表示引用上面定義的sql片段 -->
	<insert id="dynaInsert" parameterType="cn.itcast.javaee.mybatis.app14.Student">
		insert into students(<include refid="key"/>) values(<include refid="value"/>)
	</insert>
	
	
	
</mapper>

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