我有一个相当复杂的查询（对我来说）只有当传递的参数导致'dest_xdock：'时才会返回重复的结果。 $ row ['dest_xdock']作为特定值。任何人都可以确定为什么在查询中发生这种情况？我在表格中没有重复的内容。这是查询：
select
`orig_lookup`.`zipcode` AS `orig_zipcode`,
`orig_lookup`.`state` AS `orig_state`,
`orig_lookup`.`svcnotes` AS `orig_svcnotes`,
`orig_lookup`.`svcterms` AS `orig_svcterms`,
`orig_lookup`.`daysout` AS `orig_daysout`,
`orig_lookup`.`daysin` AS `orig_daysin`,
`orig_lookup`.`pcity` AS `orig_city`,
`orig_lookup`.`scac` AS `orig_scac`,
`orig_lookup`.`xdock` AS `orig_xdock`,
`orig_lookup`.`scac2` AS `orig_scac2`,
`orig_lookup`.`xdock2` AS `orig_xdock2`,
`orig_lookup`.`scac3` AS `orig_scac3`,
`orig_lookup`.`xdock3` AS `orig_xdock3`,
`orig_ssas`.`ssa` AS `orig_ssa`,
`orig_hcas`.`hca` AS `orig_hca`,
`dest_lookup`.`zipcode` AS `dest_zipcode`,
`dest_lookup`.`state` AS `dest_state`,
`dest_lookup`.`svcnotes` AS `dest_svcnotes`,
`dest_lookup`.`svcterms` AS `dest_svcterms`,
`dest_lookup`.`daysout` AS `dest_daysout`,
`dest_lookup`.`daysin` AS `dest_daysin`,
`dest_lookup`.`pcity` AS `dest_city`,
`dest_lookup`.`scac` AS `dest_scac`,
`dest_lookup`.`xdock` AS `dest_xdock`,
`dest_lookup`.`scac2` AS `dest_scac2`,
`dest_lookup`.`xdock2` AS `dest_xdock2`,
`dest_lookup`.`scac3` AS `dest_scac3`,
`dest_lookup`.`xdock3` AS `dest_xdock3`,
`dest_ssas`.`ssa` AS `dest_ssa`,
`dest_hcas`.`hca` AS `dest_hca`,
`tbl_matx_20160321`.`trmnljoin` AS `TrmnlMatx`,
`tbl_matx_20160321`.`trmnlsvcdays` AS `TrmnlSvcDays`,
`tbl_matx_20160321`.`trmnltranspts` AS `TrmnlTransPts`,
IF(ISNULL(`orig_lookup`.`daysin`+ `dest_lookup`.`daysout`+ `tbl_matx_20160321`.`trmnlsvcdays`), 'No Service',(`orig_lookup`.`daysin`+ `dest_lookup`.`daysout`+ `tbl_matx_20160321`.`trmnlsvcdays`)) AS `TotalSvcDays`
FROM ((`tbl_uscomp_20160321` AS `orig_lookup` LEFT JOIN `tbl_hcas_20160321` AS `orig_hcas` ON `orig_lookup`.`zipcode` = `orig_hcas`.`zipcode` LEFT JOIN `tbl_ssas_20160321` AS `orig_ssas` ON `orig_lookup`.`zipcode` = `orig_ssas`.`zipcode`)
INNER JOIN (`tbl_uscomp_20160321` AS `dest_lookup` LEFT JOIN `tbl_hcas_20160321` AS `dest_hcas` ON `dest_lookup`.`zipcode` = `dest_hcas`.`zipcode` LEFT JOIN `tbl_ssas_20160321` AS `dest_ssas` ON `dest_lookup`.`zipcode` = `dest_ssas`.`zipcode`)
INNER JOIN `tbl_matx_20160321` ON (`orig_lookup`.`xdock` = `tbl_matx_20160321`.`otrmnl` AND `dest_lookup`.`xdock` = `tbl_matx_20160321`.`dtrmnl`))
WHERE `orig_lookup`.`zipcode` = '$ziporig' AND `dest_lookup`.`zipcode` = '$zipdest'",