Mapper XML Specification

Contributor contributes new data tables to Apache Linkis. When writing Mapper XML, the following specifications must be followed for development.

• In mapper.xml namespace is equal to java interface address
• The method name in the java interface is the same as the id of the statement in XML
• The input parameter type of the method in the java interface is the same as the type specified by the parameterType of the statement in XML
• The return value type of the method in the java interface is the same as the type specified by the resultType of the statement in XML
• All mysql keywords in XML use lowercase uniformly
• Abstract SQL fragments for excessive query fields
• It is recommended to use Integer for the integer return value type, which can distinguish between unassigned and 0 cases. For example, if the return value is determined to be a number, int can be used. Other data types are similar.
• For placeholders, use #{name} instead of ${name}. Fuzzy query can use CONCAT(‘%’,#{sname},’%’)
• For sql statement writing, no annotation method is used, and it is uniformly written in the XML file

The java interface must contain @Param, and the XML can not contain parameterType

// java interface
User selectUserById(@Param("id") Integer id);
// XML file
<select id="selectUserById" resultType="userMap">
    select id, name
    from user
    where id = #{id}
</select>

// java interface
List<User> userListByIds(@Param("ids") List<Integer> ids);
// XML file
<select id="userListByIds" resultMap="userMap">
    select id, name
    from user
    where id in
        <foreach collection="ids" separator="," open="(" close=")" item="item">
            #{item}
        </foreach>
</select>

// java interface
User queryByParams(@Param("map") Map<String, Object> parasms);
// XML file
<select id="queryByParams" resultMap="userMap">
    select id, name
    from user
    where id = #{map.id} and name = #{map.name}
</select>

// java interface
User queryByUser(@Param("user") User user);
// XML file
<select id="queryByUser" resultMap="userMap">
    select id, name
    from user
    where id = #{user.id} and name = #{user.name}
</select>

// java interface
User queryByIdAndName(@Param("id") Integer id, @Param("name") String name);
// XML file
<select id="queryByIdAndName" resultMap="userMap">
    select id, name
    from user
    where id = #{id} and name = #{name}
</select>

Use spaces and indentation reasonably to enhance readability. Examples of various types of SQL statements are as follows

<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.apache.linkins.dao.mapper.UserMapper">
    -- add a statement
    <insert id="insert">
        insert into user (id, name)
        values ​​(1, 'z3');
    </insert>
    -- delete statement
    <delete id = "deleteUserByIdAndName">
        delete from user
        where name = #{name}
            and id = #{id}
    </delete>
    -- modify the statement
    <update id="updateUserById">
        update user
        set name = #{name}
        where id = #{id}
    </update>
    -- Check for phrases
    <select id="selectUserByName" resultMap="userMap">
        select id, name
        from user
        where name = 'z3'
    </select>
    -- sql fragment
    <sql id="user">
        id,
        name
    </sql>
    -- Quote
    <include refid="user"/>
    -- resultMap
    <resultMap type="Assets" id="userMap">  
        <id property="id" column="id" />  
        <result property="name" column="name" />
    </resultMap>
    -- Quote
    <select id="queryListByParam" parameterType="map" resultMap="userMap">
        do...
    </select>
    -- conditional judgment
    <if test="name != null and name != ''">  
        name = #{name}  
    </if>
    -- sub query
    <select id="selectUserByTeacherIdAndName" resultMap="userMap">
        select u.id, u.name
        from user u
        where u.name in (
            select t.name
            from teacher t
            where t.id = 1
                and t.name = 'z3'
            )
            and u.id = 2
    </select>
</mapper>