The last article completed the construction of the MyBatis environment and the first MyBatis program preparation of the first MyBatis program, now on this basis, to achieve the increase, deletion, change and check database
For the following operations, you only need to modify interfacesUserMapperAnd XML configuration filesUserMapper.xmlCan be
It is worth mentioning that if IDEA is connected to the database, the following mapper file has code prompts when writing SQL statements

SELECT operation

Add a query method to the interface, which is queried by User’s ID

User getUserById(Integer id);
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Usermapper. XML in the namespace isUserMapperthemapperNext, add oneselectThe module

<select id="getUserById" resultType="com.du.mybatis.pojo.User" parameterType="int">
    select id, `name`, address
    from user
    where id = #{id};
</select>
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idIs the corresponding method name,resultTypeIs the returned parameter type,parameterTypeEnter the parameter type for the method
Input parameters pass#{id}To obtain
The test method

  @Test
  public void getUserByIdTest(a) {
    try (SqlSession sqlSession = Utils.getSqlSession()) {
      UserMapper mapper = sqlSession.getMapper(UserMapper.class);
      User userById = mapper.getUserById(2); System.out.println(userById); }}Copy the code

INSERT, INSERT

Insert method

int insertUser(User user);
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joininsertThe module

<insert id="insertUser" parameterType="com.du.mybatis.pojo.User">
    insert into user(id, name, address)
    values (#{id}, #{name}, #{address});
</insert>
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The test method

  @Test
  public void insertUserTest(a) {
    try (SqlSession sqlSession = Utils.getSqlSession()) {
      UserMapper mapper = sqlSession.getMapper(UserMapper.class);
      int res = mapper.insertUser(new User(10."Li bai"."India"));
      if (res > 0)
        System.out.println("Insert successful");
      else
        System.out.println("Insert failed");
      sqlSession.commit(); // Commit transaction, must!}}Copy the code

A transaction must be committed if it involves modifying the database!!

UPDATE, modify operation

Change the method

int updateUser(User user);
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joinupdateThe module

<update id="updateUser" parameterType="com.du.mybatis.pojo.User">
    update user
    set name=#{name},
        address = #{address}
    where id = #{id};
</update>
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The test code

  @Test
  public void updateUserTest(a) {
    try (SqlSession sqlSession = Utils.getSqlSession()) {
      UserMapper mapper = sqlSession.getMapper(UserMapper.class);
      int res = mapper.updateUser(new User(3."Du fu"."Tibet"));
      if (res > 0)
        System.out.println("Update successful");
      else
        System.out.println("Update failed"); sqlSession.commit(); }}Copy the code

4. DELETE

Delete methods

int deleteUserByID(int id);
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joindeleteThe module

<delete id="deleteUserByID" parameterType="int">
    delete
    from user
    where id = #{id};
</delete>
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The test code

  @Test
  public void deleteUserByIdTest(a) {
    try (SqlSession sqlSession = Utils.getSqlSession()) {
      UserMapper mapper = sqlSession.getMapper(UserMapper.class);
      int res = mapper.deleteUserByID(2);
      if (res > 0)
        System.out.println("Deleted successfully");
      else
        System.out.println("Delete failed"); sqlSession.commit(); }}Copy the code

Five, multi-parameter input, pass`Map`implementation

Delete method. The input parameter ismap

int deleteUserByNameAndAddress(Map<String, String> map);
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joindeleteThe module

<delete id="deleteUserByNameAndAddress" parameterType="map">
    delete
    from user
    where name = #{name}
      and address = #{address};
</delete>
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parameterTypeMap (lowercase, which is an alias)
Directly in the# {}Middle finger is good
The test code

  @Test
  public void deleteUserByNameAndAddressTest(a) {
    try (SqlSession sqlSession = Utils.getSqlSession()) {
      UserMapper mapper = sqlSession.getMapper(UserMapper.class);
      Map<String, String> map = new HashMap<String, String>();
      map.put("name"."Li bai");
      map.put("address"."India");
      int res = mapper.deleteUserByNameAndAddress(map);
      if (res > 0)
        System.out.println("Deleted successfully");
      else
        System.out.println("Delete failed"); sqlSession.commit(); }}Copy the code

Vi. Complete code

public interface UserMapper {
  /** * query all users **@return* /
  List<User> getUserList(a);

  /** * query User ** by ID@return* /
  User getUserById(Integer id);

  /** * insert a User **@param user
   * @return0 indicates failure; >0 indicates success */
  int insertUser(User user);

  /** * delete User ** by ID@param id
   * @return* /
  int deleteUserByID(int id);

  /** * Update user ** based on ID@param user
   * @return* /
  int updateUser(User user);

  /** * Delete element * based on name and address@param map
   * @return* /
  int deleteUserByNameAndAddress(Map<String, String> map);
}
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<! DOCTYPEmapper
        PUBLIC "- / / mybatis.org//DTD Mapper / 3.0 / EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<! -- Change to the corresponding interface -->
<mapper namespace="com.du.mybatis.dao.UserMapper">
    <! -- id = method name in interface -->
    <! ResultType = query bean, remember full path! -->
    <select id="getUserList" resultType="com.du.mybatis.pojo.User">
        select id, `name`, address
        from user;
    </select>
    <select id="getUserById" resultType="com.du.mybatis.pojo.User" parameterType="int">
        select id, `name`, address
        from user
        where id = #{id};
    </select>
    <insert id="insertUser" parameterType="com.du.mybatis.pojo.User">
        insert into user(id, name, address)
        values (#{id}, #{name}, #{address});
    </insert>
    <delete id="deleteUserByID" parameterType="int">
        delete
        from user
        where id = #{id};
    </delete>
    <update id="updateUser" parameterType="com.du.mybatis.pojo.User">
        update user
        set name=#{name},
            address = #{address}
        where id = #{id};
    </update>
    <delete id="deleteUserByNameAndAddress" parameterType="map">
        delete
        from user
        where name = #{name}
          and address = #{address};
    </delete>
</mapper>
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public class UserMapperTest {
  @Test
  public void getUserListTest(a) {
    try (SqlSession sqlSession = Utils.getSqlSession()) {
      UserMapper mapper = sqlSession.getMapper(UserMapper.class);
      List<User> userList = mapper.getUserList();
      for(User user : userList) { System.out.println(user); }}}@Test
  public void getUserByIdTest(a) {
    try (SqlSession sqlSession = Utils.getSqlSession()) {
      UserMapper mapper = sqlSession.getMapper(UserMapper.class);
      User userById = mapper.getUserById(2); System.out.println(userById); }}@Test
  public void insertUserTest(a) {
    try (SqlSession sqlSession = Utils.getSqlSession()) {
      UserMapper mapper = sqlSession.getMapper(UserMapper.class);
      int res = mapper.insertUser(new User(10."Li bai"."India"));
      if (res > 0)
        System.out.println("Insert successful");
      else
        System.out.println("Insert failed");
      sqlSession.commit(); // Commit transaction, must!}}@Test
  public void deleteUserByIdTest(a) {
    try (SqlSession sqlSession = Utils.getSqlSession()) {
      UserMapper mapper = sqlSession.getMapper(UserMapper.class);
      int res = mapper.deleteUserByID(2);
      if (res > 0)
        System.out.println("Deleted successfully");
      else
        System.out.println("Delete failed"); sqlSession.commit(); }}@Test
  public void updateUserTest(a) {
    try (SqlSession sqlSession = Utils.getSqlSession()) {
      UserMapper mapper = sqlSession.getMapper(UserMapper.class);
      int res = mapper.updateUser(new User(3."Du fu"."Tibet"));
      if (res > 0)
        System.out.println("Update successful");
      else
        System.out.println("Update failed"); sqlSession.commit(); }}@Test
  public void deleteUserByNameAndAddressTest(a) {
    try (SqlSession sqlSession = Utils.getSqlSession()) {
      UserMapper mapper = sqlSession.getMapper(UserMapper.class);
      Map<String, String> map = new HashMap<String, String>();
      map.put("name"."Li bai");
      map.put("address"."India");
      int res = mapper.deleteUserByNameAndAddress(map);
      if (res > 0)
        System.out.println("Deleted successfully");
      else
        System.out.println("Delete failed"); sqlSession.commit(); }}}Copy the code

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Add, delete, modify and check MyBatis

SELECT operation

INSERT, INSERT

UPDATE, modify operation

4. DELETE

Five, multi-parameter input, pass`Map`implementation

Vi. Complete code

Add, delete, modify and check MyBatis

SELECT operation

INSERT, INSERT

UPDATE, modify operation

4. DELETE

Five, multi-parameter input, passMapimplementation

Vi. Complete code

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