MyBatis/iBatis - reusable sql fragments in a separate SQL Map file?

问题

I would like to put sql fragments used by several of my SQL Map XML files in a separate file. At the moment, the <sql> elements with these fragments are in one of the mappers together with other elements like <select>, which makes them hard to find.
Can I have a mapper that defines just a few <sql> elements and is not used to generate an implementation to an interface? What would be the correct namespace of this mapper?

This is the SQL Map file with the framents:

<mapper namespace="com.company.project.dao.someDao">

    <sql id="whereDate">
        WHERE date(`time`) BETWEEN #{startDate} AND #{endDate}
    </sql>  

    <sql id="someOtherSqlFragment">
        ...
    </sql>

    <select id="getSomeData"
            resultType="SomeClass"
            parameterType="DateParam" >
        SELECT some_column, another_column
    </select>

        FROM some_table

        <include refid="whereDate"/>

        <include refid="otherSqlFragment"/>

    </select>

</mapper>

I'd like to separate the elements like this:
First Sql Map file:

<mapper namespace="com.company.project.dao.???">

    <sql id="whereDate">
        WHERE date(`time`) BETWEEN #{startDate} AND #{endDate}
    </sql>  

    <sql id="someOtherSqlFragment">
        ...
    </sql>

</mapper>

Second Sql Map file:

<mapper namespace="com.company.project.dao.someDao">

    <select id="getSomeData"
            resultType="SomeClass"
            parameterType="DateParam" >
        SELECT some_column, another_column
    </select>

        FROM some_table

        <include refid="whereDate"/>

        <include refid="otherSqlFragment"/>

    </select>

</mapper>

回答1:

This is exactly what a project I used to work on did. Common fragments were defined in a separate file which was included in the main iBATIS config file.

We had a SQL map file at the root named Core.ism.xml which looked like this:

<sqlMap namespace="Core" >

    <sql id="fragmentBasicAuditFieldNames">
        CreateDate, CreateUser, 
        UpdateDate, UpdateUser, UpdateCode 
    </sql>

    ....

And then in our SQL map files we could reference it like this:

<include refid="Core.fragmentBasicAuditFieldNames" />

I hope I've understood what you were asking correctly!

回答2:

Say, you have some

<mapper namespace="Common">
   <sql id="idsIn">
        ${column} IN
        <foreach item="id" collection="ids" separator="," open="(" close=")">
            #{id}
        </foreach>
    </sql>
</mapper>

Than in another mapper you can use it like:

<mapper namespace="OtherMapper">
    <sql id="someSql">
        ...
        <include refid="Common.idsIn">
            <property name="column" value="${column}"/>
            <!-- OR hardcode: <property name="column" value="id"/> -->
            <property name="filterPksTable" value="${filterPksTable}"/>
        </include>
        ...
    </sql>
</mapper>

Also, you can have a look here

来源：https://stackoverflow.com/questions/6069071/mybatis-ibatis-reusable-sql-fragments-in-a-separate-sql-map-file

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