MyBatis framework common problems and solutions

MyBatis common problems include: 1. Entity class attributes are inconsistent with database fields, the solution is to use @Column annotation mapping; 2. The update operation fails, you need to configure the update element and check the SQL statement; 3. Query result mapping error, It is necessary to check whether the resultMap configuration is correct; 4. Failed to parse SQL parameters, use #{} placeholder and ensure that the parameter types match.

MyBatis framework common problems and solutions

1. Entity class attributes are inconsistent with database fields

Solution: Use the @Column annotation to map entity class attributes and database fields.

@Column(name = "user_name")
private String name;

2. Unable to perform update operations using MyBatis

Solution: Make sure update## is configured in the MyBatis configuration file # element and make sure the SQL statement is correct.

<update id="updateUser" parameterType="User">
  UPDATE user SET name = #{name} WHERE id = #{id}
</update>

3. MyBatis query result mapping error

Solution: Check whether the resultMap element is configured correctly and ensure that the column Name matches entity class attribute.

<resultMap id="userResultMap" type="User">
  <result property="id" column="id" />
  <result property="name" column="name" />
</resultMap>

4. MyBatis cannot parse SQL parameters

Solution: Make sure to use the correct #{}placeholder character and make sure the parameter type matches the SQL statement.

Practical case:

Problem: The data cannot be queried, and MyBatis reports a UserMapper class exception not found.

Solution: Configure the mapper tag in mybatis-config.xml and specify the package path of UserMapper and class name.

<mapper namespace="com.example.mapper.UserMapper" />

Problem: The update operation failed and MyBatis printed SQL statement error information.

Solution: Check whether there are syntax errors in the SQL statement and ensure that the column names match the entity class attributes.

Problem: MyBatis reports an error when parsing the XML configuration file.

Solution: Check whether the XML file syntax is correct and make sure you are using the correct DTD or XSD file.

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