the use of <set> tag may occur exceptions,for the the field of the domain is primitive type.

[peiquan]

For example,in the koan21-mapper.xml ,given below sql can't pass the test(Koan21#learnToUseDynamicSetTagToAllowVariableNumberOfSetClauses)..

<!-- SET -->
 UPDATE film
<set>
    <if test="title != null">
        title=#{title},
    </if>
    <if test="retal_duration != null">
        rental_duration=#{rentalDuration},
    </if>
    <if test="rentalRate != null">
        rental_rate=#{rentalRate}
    </if>
</set>
WHERE film_id = #{id}
<!-- use dynamic sql clause(s) to optionally update title, rental_duration and/or rental_rate -->

maybe,I haven't understood the mybatis

sometimes,i also find something interesting.While you just only pass the id arg on the domain Film，the sql will be UPDATE film WHERE film_id = ?, it's a bad sql