Mybatis Select Count(*)的返回值类型介绍

Select Count(*)的返回值类型

<select id="queryAlarmStatisticalAnalysis4System" parameterType="AlarmMailSendLog"
           resultType="java.lang.Integer">
       select count(*) from mon_alarm_mail_send_log
       where is_del = '0'
       <if test="airport != null and airport != ''">
           and airport = #{airport}
       </if>
       <if test="system != null and system != ''">
           and system = #{system}
       </if>
       <if test="relateTable != null and relateTable != ''">
           and relate_table = #{relateTable}
       </if>
       <if test="params.startTime != null and params.startTime != ''">
           and send_time &gt;= to_date(#{params.startTime},'yyyy-MM-dd HH24:mi:ss')
       </if>
       <if test="params.endTime != null and params.endTime != ''">
           and send_time &lt;= to_date(#{params.endTime},'yyyy-MM-dd HH24:mi:ss')
       </if>
   </select>

类似于select count(*)的语句的返回值为java.lang.Integer

返回Count(*)的整数值

1、mybatis中resultType定义为"java.lang.Integer"

<select id="selectNums" resultType="java.lang.Integer">
   select count(*) from tableName
 </select>

2、接口中返回值写成int，即可

int selectNums();

来源：https://blog.csdn.net/wangchaox123/article/details/90487028