如果我正确理解了您的问题,那么您正在寻找只有nm1.nm108 = 'MI'
存在的记录,否则您希望排除这些记录
尝试这样的事情
IF EXISTS(SELECT 1 FROM X12_NM1 As NM1
INNER JOIN X12_CLP As CLP
ON CLP.segment_guid = NM1.parent_segment_guid
AND NM1.Loop_Id ='2100'
WHERE nm1.nm108 = 'MI')
BEGIN
SELECT NM1.nm101,
CLP.Segment_GUID as CLPSegmentGuid
, CASE NM1.nm101
WHEN 'QC' THEN 'Patient'
WHEN 'IL' THEN 'Insured'
WHEN '74' THEN 'Corrected'
WHEN '82' THEN 'Crossover'
END As type
, NM1.NM102 As Entity_Type_Qualifier
, NM1.NM103 As Entity_Last_Name
, NM1.NM104 As Entity_First_Name
, NM1.NM105 As Entity_Middle_Name
, NM1.NM108 As Entity_Identification_Code_Type
, NM1.NM109 As Entity_Identification_Code
FROM X12_NM1 As NM1
INNER JOIN X12_CLP As CLP
ON CLP.segment_guid = NM1.parent_segment_guid
AND NM1.Loop_Id ='2100'
WHERE nm1.nm108 = 'MI'
END
ELSE
BEGIN
SELECT NM1.nm101,
CLP.Segment_GUID as CLPSegmentGuid
, CASE NM1.nm101
WHEN 'QC' THEN 'Patient'
WHEN 'IL' THEN 'Insured'
WHEN '74' THEN 'Corrected'
WHEN '82' THEN 'Crossover'
END As type
, NM1.NM102 As Entity_Type_Qualifier
, NM1.NM103 As Entity_Last_Name
, NM1.NM104 As Entity_First_Name
, NM1.NM105 As Entity_Middle_Name
, NM1.NM108 As Entity_Identification_Code_Type
, NM1.NM109 As Entity_Identification_Code
FROM X12_NM1 As NM1
INNER JOIN X12_CLP As CLP
ON CLP.segment_guid = NM1.parent_segment_guid
AND NM1.Loop_Id ='2100'
WHERE nm1.nm108 <> 'MI'
END