实际使用：
<!-- 通过查询条件查询营销活动审核列表--> <select id="findByParamsCampaign" parameterType="HashMap" resultType="java.util.HashMap"> select a.id as id, a.code as code, a.name as name, a.classify as classify, a.type as type, a.shape as shape, a.audit_status as auditStatus, a.audit_remark as auditRemark, a.time_end as timeEnd, a.time_start as timeStart, a.create_org as createOrg, a.create_time as createTime, a.create_user as createUser from crm_promotion a <where> delete_flag = 0 <!-- 活动名称 --> <if test="name != null and name != ''"> and a.name like CONCAT( '%',#{name,jdbcType=VARCHAR},'%' ) </if> <!-- 活动编号 --> <if test="code != null and code !=''"> and a.code like CONCAT( '%',#{code,jdbcType=VARCHAR},'%' ) </if> <!-- 活动类型 --> <if test="type != null and type != ''"> and a.type = #{type,jdbcType=VARCHAR} </if> <!-- 参与方式 --> <if test="shape != null and shape !=''"> and a.shape = #{shape,jdbcType=VARCHAR} </if> <!-- 活动开始时间 --> <if test="startTime != null and startTime != ''"> and a.time_start <![CDATA[>=]]> #{startTime,jdbcType=TIMESTAMP} </if> <!-- 活动结束时间 --> <if test="endTime != null and endTime != ''"> and a.time_end <![CDATA[<=]]> #{endTime,jdbcType=TIMESTAMP} </if> <!-- 创建开始时间 --> <if test="cStartTime != null and cStartTime != ''"> and a.create_time <![CDATA[>=]]> #{cStartTime,jdbcType=TIMESTAMP} </if> <!-- 创建结束时间 --> <if test="cEndTime != null and cEndTime != ''"> and a.create_time <![CDATA[<=]]> #{cEndTime,jdbcType=TIMESTAMP} </if> <!-- 创建人 --> <if test="createUser != null and createUser !=''"> and a.create_user like CONCAT( '%',#{createUser,jdbcType=DECIMAL},'%' ) </if> <if test="channelId != null and channelId != ''"> and exists ( select 1 from crm_promotion_channel b <where> b.promotion_id = a.id <if test="channelId != null"> and b.channel_id = #{channelId,jdbcType=VARCHAR} </if> </where> ) </if> //如果副表有多个条件<if test="realName != null and realName != '') or (mobile != null and mobile != '')"> and EXISTS (SELECT c.supplier_id from sup_supplier_contacts c WHERE c.supplier_id = a.id <if test="realName !=null and realName != ''"> and c.real_name like concat('%',#{realName,jdbcType=VARCHAR},'%') </if> <if test="mobile !=null and mobile != ''"> and c.mobile = #{mobile,jdbcType=VARCHAR} </if> ) </if> </where> order by a.create_time DESC </select>exists 方式查询 比 in 方式查询效率高，但in 可读性较好。建议尽可能使用exists方式，避免使用子查询，除非in 的参数为数值列表。
