What is the detailed explanation of the mybatis tag?

mybatis tags include: 1. tag; 2. tag; 3. tag; 4. tag; 5. tag; 6. tag; 7. tag; 8. tag. Detailed introduction: 1. The tag is used to define a query SQL statement; 2. The tag is used to define an insert data, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

MyBatis is an excellent persistence layer framework that supports customized SQL, stored procedures and advanced mapping. In MyBatis, labels are important elements for configuring SQL statements and mapping relationships. Commonly used tags in MyBatis will be explained in detail below:

1, Tag

Function: Used to define a query SQL statement.

Attributes: id, resultType, parameterType, sql fragment, etc.

Example:

xml`<select id="selectUserById" parameterType="int" resultType="User">  
  SELECT * FROM user WHERE id = #{id}  
</select>`

2. tag

Function: Used to define a SQL statement for inserting data.

Attributes: id, parameterType, useGeneratedKeys, keyProperty, etc.

Example:

xml`<insert id="insertUser" parameterType="User">  
  INSERT INTO user (name, age) VALUES (#{name}, #{age})  
</insert>`

3. tag

Function: Used to define a SQL statement that updates data.

Attributes: id, parameterType.

Example:

xml`<update id="updateUser">  
  UPDATE user SET name=#{name}, age=#{age} WHERE id=#{id}  
</update>`

4. tag

Function: Used to define a SQL statement to delete data.

Attributes: id, parameterType.

Example:

xml`<delete id="deleteUserById">  
  DELETE FROM user WHERE id=#{id}  
</delete>`

5, tag

Function: Define the mapping rules of the result set. It is often used within the tag.

Attributes: id, type, autoMapping, etc.

Example:

xml`<resultMap id="UserResultMap" type="User">  
  <id property="id" column="id"/>  
  <result property="name" column="name"/>  
  <result property="age" column="age"/>  
</resultMap>`

6, tag

Function: Define type aliases to facilitate the use of short type names.

Attributes: id, type.

Example:

xml`<typeAliases>  
  <typeAlias alias="User" type="com.example.User"/>  
</typeAliases>`

7, tag

Function: Define reusable SQL fragments. It is often used in other SQL statements and is referenced through ${}.

Attribute: id.

Example:

xml`<sql id="userColumns">name, age</sql>  
<select id="selectUsers" resultType="User">  
  SELECT ${userColumns} FROM user  
</select>`

8, tag (Note: In newer versions of MyBatis, it is recommended to use and ${} to Reference SQL fragment)

Function: Introduce the defined SQL fragment. It is often used in other SQL statements.

Attribute: id.

Example: (same as example)

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