• IDEA 03 (动态sql和分页)

    目录

    一、foreach标签

    1、BookMapper.xml

    2、BookMapper

    3、BookBizImpl

    4、BookBiz

    5、BookBizImplTest

    二、模糊查询

    1、test1

    ①BookBiz

     ②BookBizImpl

     ③BookMapper.xml

    ④BookMapper.java

    ⑤BookBizImplTest

    2、test2

    ①BookBiz

     ②BookBizImpl

     ③BookMapper.xml

     ④BookMapper.java

    ⑤BookBizImplTest

    3、test3

    ①BookBiz

    ②BookBizImpl

    ③BookMapper.xml

    ④BookMapper.java

    三、结果集的处理

    1、list1

    ①BookBiz

    ②BookBizImpl

    ③BookMapper.xml

    ④BookMapper.java

    ⑤BookVo

    ⑥BookBizImplTest

    2、list2

    ①BookBiz

    ②BookBizImpl

    ③BookMapper.xml

    ④BookMapper.java

    ⑤BookVo

     ⑥BookBizImplTest

    3、list3

    ①BookBiz

    ②BookBizImpl

    ③BookMapper.xml

    总结：

    1、MyBatis中#和$的区别

    MyBatis中#和$的区别

     

    一、foreach标签

    1、BookMapper.xml

    2.   <select id="selectByIn" resultMap="BaseResultMap" parameterType="java.util.List" >
    3.     select
    4.     <include refid="Base_Column_List" />
    5.     from t_mvc_book
    6.     where bid in
    7.     <foreach collection="bookIds" open="(" close=")" separator="," item="bid">
    8.       #{bid}
    9.     foreach>
    10.   select>

    2、BookMapper

    1. //  通过in关键字进行查询：讲解foreach 标签的使用
    2. //    如果说参数是非实体类(book,Order,....)，那么急的加上注解 @param,bookIds是对应collection属性的
    3.     List selectByIn(@Param("bookIds") List bookIds);

    3、BookBizImpl

    1.  @Override
    2.     public List selectByIn(List bookIds) {
    3.         return bookMapper.selectByIn(bookIds);
    4.     }

    4、BookBiz

    List selectByIn(List bookIds);

    5、BookBizImplTest

    1. @Test
    2.     public void selectByIn() {
    3.         List bookIds = Arrays.asList(new Integer[]{31, 32, 33, 34});
    4.         bookBiz.selectByIn(bookIds).forEach(System.out::println);
    5.     }

     运行效果：

     

     

    二、模糊查询

    1、test1

    ①BookBiz

    public List selectBooksLike1(String bname);

     ②BookBizImpl

    1. @Override
    2.     public List selectBooksLike1(String bname) {
    3.         return bookMapper.selectBooksLike1(bname);
    4.     }

     ③BookMapper.xml

    ④BookMapper.java

    List selectBooksLike1(@Param("bname") String bname);

    ⑤BookBizImplTest

    1. @Test
    2.     public void selectBooksLike1() {
    3.         bookBiz.selectBooksLike1("%圣墟%").forEach(System.out::println);
    4.     }

    2、test2

    ①BookBiz

    public List selectBooksLike2(String bname);

     ②BookBizImpl

    1. @Override
    2.     public List selectBooksLike2(String bname) {
    3.         return bookMapper.selectBooksLike2(bname);
    4.     }

     ③BookMapper.xml

     ④BookMapper.java

    List selectBooksLike2(@Param("bname") String bname);

    ⑤BookBizImplTest

    1. @Test
    2.     public void selectBooksLike2() {
    3.         bookBiz.selectBooksLike2("%圣墟%").forEach(System.out::println);
    4.     }

    运行效果：

    3、test3

    ①BookBiz

    public List selectBooksLike3(String bname);

    ②BookBizImpl

    1. @Override
    2.     public List selectBooksLike3(String bname) {
    3.         return bookMapper.selectBooksLike3(bname);
    4.     }

    ③BookMapper.xml

    1. <select id="selectBooksLike3" resultType="com.chenchen.model.Book" parameterType="java.lang.String">
    2.   select * from t_mvc_book where bname like concat('%',#{bname},'%')
    3. select>

    ④BookMapper.java

    List selectBooksLike3(@Param("bname") String bname);

    运行效果：

    三、结果集的处理

    1、list1

    ①BookBiz

    List list1();

    ②BookBizImpl

    1. @Override
    2.     public List<Book> list1() {
    3.         return bookMapper.list1();
    4.     }

    ③BookMapper.xml

    1.  <select id="list1" resultMap="BaseResultMap">
    2.   select * from t_mvc_book
    3. select>

    ④BookMapper.java

    1. //    list1 list2的结论是，对于单表查询而言，可以用resultmap/resulttype接收，但是多表必须用resultmap接收
    2.     List list1();

    ⑤BookVo

    1. package com.chenchen.model;
    2.  
    3. import java.util.List;
    4.  
    5. public class BookVo extends Book{
    6.     private List bookIds;
    7.  
    8.     public List getBookIds() {
    9.         return bookIds;
    10.     }
    11.  
    12.     public void setBookIds(List bookIds) {
    13.         this.bookIds = bookIds;
    14.     }
    15. }

    ⑥BookBizImplTest

    1.  @Test
    2.     public void list1() {
    3.         bookBiz.list1().forEach(System.out::println);
    4.     }

     运行效果: 

    2、list2

    ①BookBiz

    List list2();

    ②BookBizImpl

    1. @Override
    2.     public List list2() {
    3.         return bookMapper.list2();
    4.     }

    ③BookMapper.xml

    1. select>
    2.   <select id="list2" resultType="com.chenchen.model.Book">
    3.   select * from t_mvc_book
    4. select>

    ④BookMapper.java

     List list2();

    ⑤BookVo

    1. package com.chenchen.model;
    2.  
    3. import java.util.List;
    4.  
    5. public class BookVo extends Book{
    6.     private List bookIds;
    7.  
    8.     public List getBookIds() {
    9.         return bookIds;
    10.     }
    11.  
    12.     public void setBookIds(List bookIds) {
    13.         this.bookIds = bookIds;
    14.     }
    15. }
    16.

     ⑥BookBizImplTest

    1.  @Test
    2.     public void list2() {
    3.         bookBiz.list2().forEach(System.out::println);
    4.     }

    运行效果：

    3、list3

    ①BookBiz

    List<Book> list3(BookVo vo);

    ②BookBizImpl

    1. @Override
    2.     public List list3(BookVo vo) {
    3.         return bookMapper.list3(vo);
    4.     }

    ③BookMapper.xml

    1.   <select id="list3" resultType="com.chenchen.model.Book" parameterType="com.chenchen.model.BookVo">
    2.     select * from t_mvc_book where bid in
    3.     <foreach collection="bookIds" open="(" close=")" separator="," item="bid">
    4.       #{bid}
    5.     foreach>
    6.   select>

    运行结果

    总结：

    1、MyBatis中#和$的区别

    MyBatis中#和$的区别

          1.#将传入的数据都当成一个字符串，会对自动传入的数据加一个双引号。
              如：order by #user_id#，如果传入的值是111,那么解析成sql时的值为order by ‘111’,
            如果传入的值是id，则解析成的sql为order by “id”.
            原文链接：https://blog.csdn.net/weixin_67677668/article/details/126291580

           2.$将传入的数据直接显示生成在sql中。
            如：order by u s e r i d user_iduser 
            i d，如果传入的值是111,那么解析成sql时的值为order by user_id,
            如果传入的值是id，则解析成的sql为order by id

    3.#方式能够很大程度防止sql注入。

     

    4.$方式无法防止Sql注入。

    5.$方式一般用于传入数据库对象，例如传入表名.

    6.一般能用#的就别用$.

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  • 原文地址：https://blog.csdn.net/m0_67094505/article/details/126298758