Mybatis parameter (Parameters) pass

1.. Single parameter

Values of basic type, object type, collection type can be accepted.In this case, MyBatis can use this parameter directly without any processing.

<!-- according to id Query a record in a data table and encapsulate it User object -->
<select id="selectById"  resultType="com.softjx.model.User">
 select t_id as id,t_username as username,t_password password from t_user where t_id=#{id};
</select>


<!-- according to id Query a record in a data table usingparameterType Limit the type of parameter,Parameter variable names can be defined arbitrarily and are not javabean Attribute control in-->
<select id="selectById1" parameterType="java.lang.Integer" resultType="com.softjx.model.User">
 select t_id as id,t_username as username,t_password password from t_user where t_id=#{id1};
</select>

2.POJO

When these parameters belong to our business POJO, we pass the POJO directly.

<!-- Add User -->
<insert id="insertUser">
  insert into t_user (t_username,t_password)
  values (#{username},#{password})
</insert>


<!-- Add User -->
<!-- Parameters can be omitted,In any case, the variable name is javabean Medium Property Name -->
<insert id="insertUser1" parameterType="com.softjx.model.User">
  insert into t_user (t_username,t_password)
  values (#{username},#{password})
</insert>

3.Map

We can also encapsulate multiple parameters as map s and pass them directly.

public int insertUser2(Map<String ,Object> map);



<!-- Add User -->
<!-- The parameter is map,The variable name is arbitrary, when called, map Of key Consistent with variable name ,Parameters can also be omitted-->
<insert id="insertUser2" parameterType="java.util.Map">
  insert into t_user (t_username,t_password)
  values (#{a},#{b})
</insert>


                         @Test
            public void TestInserUser2() {
                    System.out.println("Add a user");
                    try {
                        UserMapper mapper=session.getMapper(UserMapper.class);
                        System.out.println(mapper);
                        Map<String,Object> map=new HashMap<String,Object>();
                        map.put("a", "lisi");
                        map.put("b", "222222");
                        int count=mapper.insertUser2(map);
                        session.commit();//Be sure to submit here, or the data won't go into the database 
                        //session.rollback();
                        System.out.println(count);
                    } finally {
                        session.close();
                    }

                }
        

4. Multiple parameters

Any number of parameters will be repackaged by MyBatis as a Map and passed in.The key of a Map is param1, param2, or 0, 1, and the value is the value of the parameter.

//Add User
    public int insertUser3(String name,String pass);

<!-- Add User -->
<!-- With multiple parameters,Parameter Name #{param1},#{param2}，perhaps#{0},#{1},Cannot use parameter name-->
<insert id="insertUser3" parameterType="java.util.Map">
  insert into t_user (t_username,t_password)
  values (#{param1},#{param2})
</insert>

<insert id="insertUser3" parameterType="java.util.Map">
  insert into t_user (t_username,t_password)
  values (#{0},#{1})
</insert>

@Test
 public void TestInserUser3() {
     System.out.println("Add a user");
     try {
          UserMapper mapper=session.getMapper(UserMapper.class);
          System.out.println(mapper);
          int count=mapper.insertUser3("aaa","bbb");
          session.commit();//Be sure to submit here, or the data won't go into the database 
          //session.rollback();
          System.out.println(count);
          } finally {
              session.close();
          }

 }

5. Named parameters

Give the parameters a name of @Param, and MyBatis encapsulates them in a map with the key being our own name.

//Add User
    public int insertUser4(@Param("name")String name,@Param("pass")String pass);

<!-- Add User -->
<!-- With multiple parameters,Use@Param annotation,Parameter names are defined directly. #{name},#{pass}Or,#{param1},#{param2}，Out-of-service#{0},#{1}-->
<insert id="insertUser4" parameterType="java.util.Map">
  insert into t_user (t_username,t_password)
  values (#{name},#{pass})
</insert>

@Test
public void TestInserUser4() {
    System.out.println("Add a user");
    try {
        UserMapper mapper=session.getMapper(UserMapper.class);
        System.out.println(mapper);
        int count=mapper.insertUser4("song","555");
            session.commit();//Be sure to submit here, or the data won't go into the database 
            //session.rollback();
            System.out.println(count);
        } finally {
            session.close();
            }

    }