-- Check quote QT-2602-0050 and its customer
DECLARE @QuoteNumber NVARCHAR(50) = 'QT-2602-0050';

-- Find the quote and customer info
SELECT
    q.Id AS QuoteId,
    q.QuoteNumber,
    q.CustomerId,
    CASE WHEN q.CustomerId IS NULL THEN 1 ELSE 0 END AS IsProspect,
    q.ProspectCompanyName,
    q.ProspectContactName,
    q.IsDeleted AS QuoteIsDeleted,
    c.Id AS CustomerIdFromTable,
    c.CompanyName AS CustomerCompanyName,
    c.IsDeleted AS CustomerIsDeleted
FROM Quotes q
LEFT JOIN Customers c ON q.CustomerId = c.Id
WHERE q.QuoteNumber = @QuoteNumber;

-- Show all prospect and customer fields
SELECT
    QuoteNumber,
    CustomerId,
    CASE WHEN CustomerId IS NULL THEN 'YES' ELSE 'NO' END AS IsProspect,
    ProspectCompanyName,
    ProspectContactName,
    ProspectEmail,
    ProspectPhone
FROM Quotes
WHERE QuoteNumber = @QuoteNumber;