How could I use update statement using <if> statement on MyBatis

Question

I want to know how to use if statement like below case

<update id="update"
    parameterType="com.MyClass">
    UPDATE
        Board SET Status = 1
    <where>
        <if test="A != null and A.length() > 0">AND A = ${A}</if>
    </where>
</update>

This statement works when A!=null and A.length() > 0.

But if A==null, then update whole rows set 1 cause there is no where conditions.

Is there any way to update if there is proper condition, otherwise skip or ignore?

thanks

Answer 1

<update id="update"
    parameterType="com.MyClass">
    UPDATE
        Board SET Status = 1
    <where>
        <choose>
            <when test="A != null and A.length() > 0">
                 AND A = ${A}
            </when>
            <otherwise>
                 AND 0 = 1
            </otherwise>
        </choose>
    </where>
</update>

With condition 0 = 1 the where fails and no updates are done