Mybatis模糊查询的写法

1.mybatis的like模糊查询相对于其它关键字或特殊符号装配数据比较特殊

写法： like '%${projectName}%' 

样例:

SELECT IFNULL(COUNT(taskId),0) as nums  FROM (        SELECT DISTINCT        f.taskId as taskId,        CONCAT(s.projectName,'-',s.projectNumber)AS taskName,        s.departId as departId        FROM        jbpm4_task task        LEFT JOIN jbpm4_participation pt ON pt.TASK_ = task.DBID_        JOIN process_form f ON f.taskId = task.DBID_        JOIN process_run r ON r.runId = f.runId        JOIN sl_smallloan_project s ON s.projectId = r.projectId        JOIN bp_product_parameter b ON s.productId = b.id        WHERE        task.ASSIGNEE_ = #{userId1}        AND task.STATE_ = 'open'        OR (        task.ASSIGNEE_ IS NULL        AND pt.TYPE_ = 'candidate'        AND (        pt.userId_ = #{userId2}        OR        pt.groupId_ = #{groupId}        )        )        ) as g        <where>            1=1            <if test="branchId!=null">                AND g.departId = #{branchId}            </if>            <if test="projectName!=null">                AND g.taskName like '%${projectName}%'            </if>        </where>