activiti视图查询待办

SELECT
	`a`.`ID_` AS `TASK_ID`,
	`a`.`PROC_INST_ID_` AS `PROC_INST_ID`,
	`a`.`PROC_DEF_ID_` AS `PROC_DEF_ID_`,
	`a`.`TASK_DEF_KEY_` AS `ACT_ID`,
	`a`.`NAME_` AS `ACT_NAME`,
	`a`.`ASSIGNEE_` AS `ASSIGNEE`,
	`a`.`DELEGATION_` AS `DELEGATION_ID`,
	`a`.`DESCRIPTION_` AS `DESCRIPTION`,
	`a`.`CREATE_TIME_` AS `CREATE_TIME`,
	`a`.`DUE_DATE_` AS `DUE_DATE`,
	`i`.`USER_ID` AS `CANDIDATE`,
	`f`.`KEY_` AS `KEY_` 
FROM
	((
			`act_ru_task` `a`
			LEFT JOIN (
			SELECT DISTINCT
				`u`.`TASK_ID_` AS `TASK_ID_`,
				`u`.`USER_ID` AS `USER_ID` 
			FROM
				(
				SELECT
					`i`.`TASK_ID_` AS `TASK_ID_`,
					`i`.`USER_ID_` AS `USER_ID` 
				FROM
					( `act_ru_identitylink` `i` JOIN `act_ru_task` `t` ) 
				WHERE
					((
							`i`.`TASK_ID_` IS NOT NULL 
							) 
						AND ( `i`.`USER_ID_` IS NOT NULL ) 
						AND ( `i`.`TASK_ID_` = `t`.`ID_` ) 
						AND isnull( `t`.`ASSIGNEE_` ) 
					AND ( `i`.`TYPE_` = 'candidate' )) UNION
				SELECT
					`i`.`TASK_ID_` AS `TASK_ID_`,
					`r`.`USER_ID_` AS `USER_ID` 
				FROM
					(( `act_ru_identitylink` `i` JOIN `act_id_membership` `r` ) JOIN `act_ru_task` `t` ) 
				WHERE
					((
							`i`.`TASK_ID_` IS NOT NULL 
							) 
						AND ( `i`.`GROUP_ID_` IS NOT NULL ) 
						AND ( `i`.`TASK_ID_` = `t`.`ID_` ) 
						AND isnull( `t`.`ASSIGNEE_` ) 
						AND ( `i`.`TYPE_` = 'candidate' ) 
					AND ( `i`.`GROUP_ID_` = `r`.`GROUP_ID_` ))) `u` 
				) `i` ON ((
					`a`.`ID_` = `i`.`TASK_ID_` 
				)))
		LEFT JOIN `act_re_procdef` `f` ON ((
			`a`.`PROC_DEF_ID_` = `f`.`ID_` 
	)))