no getter for property named 'power_state

错误信息：nested exception is org.apache.ibatis.reflection.ReflectionException: There is no getter for property named 'power_state' in 'class com.epusoft.modules.customer.entity.Customer' 

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DAO

    <select id="statics" resultType="String">
		SELECT
		count(*)
		FROM  customer a
		<include refid="customerJoins" />
        WHERE a.del_flag = #{DEL_FLAG_NORMAL}
		<if test=" powerState != null and powerState != ''">
			AND a.power_state=#{powerState}
		</if>
		<if test=" name != null and name != ''">
			AND a.name=#{name}
		</if>
		<if test=" idCard != null and idCard != ''">
			AND a.id_card=#{idCard}
		</if>
	</select>

　　#{powerState}而非#{power_state}