Try this wiki post and see if it helps clear some stuff up http://opensource2.atlassian.com/confluence/oss/display/IBATIS/How+do+I+ get+around+the+N+Plus+1+selects+problem
-----Original Message----- From: Tony Qian [mailto:[EMAIL PROTECTED] Sent: Wednesday, January 11, 2006 1:32 PM To: [email protected] Subject: grougBy issue All, I know this has been posted before. I have read a number of archived emails regarding this issue and also the example by Clinton. I just cannot make it work. The property parameters is always null. (btw, i made it work using sub-select strategy). I just want to improve the performance. Here is my mapping: <resultMap id="select-sessionCommon" class="sessionCommon" groupBy="brandId"> <result property="brandId" column="brand_id" /> <result property="parameters" resultMap="CommonSession.elementMap" /> </resultMap> <resultMap id="elementMap" class="element"> <result property="value" column="paramete_value" /> <result property="parameter" resultMap="CommonSession.parameterMap" /> </resultMap> <resultMap id="parameterMap" class="parameter" > <result property="parameterId" column="parameter_id" /> <result property="name" column="parameter_name" /> <result property="description" column="description" /> </resultMap> <select id="selectCommonSession" parameterClass="string" resultMap="select-sessionCommon" > SELECT distinct SP.parameter_id, SP.parameter_name, SP.description, SC.parameter_value , SC.brand_id FROM SESSION_INFO_COMMON as SC, SESSION_PARAMETER as SP where SP.parameter_id= SC.parameter_id and SC.brand_id=#brandId# group by SP.parameter_id,SP.parameter_name, SP.description, SC.brand_id ; </select> please let me know what i did wrong. Appreciate your help, Tony
