I'm getting an 'Ambiguous column name 'Converted_Mortgage_Number' with this SQL/php query. Can anyone please see why? DECLARE @PageSize INT, @PageNumber INT, @FirstRow INT, @LastRow INT SELECT @PageSize = $pageLength, @PageNumber = $pageNumber; SELECT @FirstRow = ( @PageNumber - 1) * @PageSize + 1, @LastRow = (@PageNumber - 1) * @PageSize + @PageSize ; WITH results AS ( SELECT t1.[Converted_Mortgage_Number], t1.[Converted_Mortgage_Advance_No], t1.[Original_Account_Number], CASE WHEN t3.description IS NOT NULL THEN t3.description ELSE t1.CACS_Location_Code END AS CACS_Location_Code, t1.[Original_Account_Number_1], t1.[Payment_Amount], t1.[Letter_ID], t1.[Batch_Activity_Date], t1.[Activity_Date], t1.[Activity_Time], CASE WHEN t6.description IS NOT NULL THEN t1.[Collection_Activity] + ' - '+ t6.description ELSE t1.[Collection_Activity] END AS [Collection_Activity], CASE WHEN t5.description IS NOT NULL THEN t1.[Party_Contact_Code] + ' - ' + t5.description ELSE t1.[Party_Contact_Code] END AS [Party_Contact_Code], CASE WHEN t7.description IS NOT NULL THEN t1.[Place_Called] + ' - ' + t7.description ELSE t1.[Place_Called] END AS [Place_Called], t1.[Promise_Amount_1], t1.[Promise_D_ate_1], t1.[Promise_Amount_2], t1.[Promise_D_ate_2], CASE WHEN t8.description IS NOT NULL THEN t1.[Non_Pay_Excuse_Code] + ' - ' + t8.description ELSE t1.[Non_Pay_Excuse_Code] END AS [Non_Pay_Excuse_Code], CASE WHEN t2.description IS NOT NULL THEN t1.CACS_State + ' - ' + t2.description ELSE t1.CACS_State END AS CACS_State, t1.[User_ID/Transaction_Type], t1.[Arrears_Amount], t4.[Sequence_Number], t4.[History_Text], ROW_NUMBER() OVER (ORDER BY [$criteria] $direction) AS RowNumber FROM format_cacs_cch AS t1 LEFT OUTER JOIN format_cacs_history_1 AS t4 ON t1.Converted_Mortgage_Number = t4.Converted_Mortgage_Number AND t1.Activity_Date = t4.Activity_Date AND t1.Activity_Time = t4.Activity_Time LEFT JOIN sd_cacs_states AS t2 ON t1.CACS_Location_Code = t2.location AND t1.CACS_State = t2.state LEFT JOIN sd_cacs_Location_details AS t3 ON t1.CACS_Location_Code = t3.code LEFT JOIN sd_party_contacted_code AS t5 ON t1.[Party_Contact_Code] = t5.code LEFT JOIN sd_collection_activity_code AS t6 ON t1.[Collection_Activity] = t6.code LEFT JOIN sd_place_called AS t7 ON t1.[Place_Called] = t7.code LEFT JOIN sd_non_pay_excuse_code AS t8 ON t1.[Non_Pay_Excuse_Code] = t8.code WHERE (t1.Converted_Mortgage_Number = '$mortgage' $additional_date_params) ) SELECT [Converted_Mortgage_Number], [Converted_Mortgage_Advance_No], [Original_Account_Number], CACS_Location_Code, [Original_Account_Number_1], [Payment_Amount], [Letter_ID], [Batch_Activity_Date], [Activity_Date], [Activity_Time], [Collection_Activity], [Party_Contact_Code], [Place_Called], [Promise_Amount_1], [Promise_D_ate_1], [Promise_Amount_2], [Promise_D_ate_2], [Non_Pay_Excuse_Code], CACS_State, [User_ID/Transaction_Type], [Arrears_Amount], [Sequence_Number], [History_Text] FROM results WHERE RowNumber BETWEEN @FirstRow AND @LastRow ORDER BY [$criteria] $direction ;