问如何连接来自三个不同别名的字符串值并在SQL Server中查找最小值

EN

SELECT 
    CustomerId,
    leaseType = (CASE 
                    WHEN MIN(CONCAT(L1.LeaseType, L2.LeaseType, L3.LeaseType)) = 'T' 
                       THEN 'Temporary' 
                    WHEN MIN(CONCAT(L1.LeaseType, L2.LeaseType, L3.LeaseType)) = 'P' 
                       THEN 'Permanant'  
                    WHEN MIN(CONCAT(L1.LeaseType, L2.LeaseType, L3.LeaseType)) = 'U'  
                       THEN 'Unknown' 
                    ELSE '' 
                 END)
FROM
    Customer
INNER JOIN 
    (SELECT
         CustomerId, LeaseType 
     FROM
         Lease 
     WHERE
         LeaseType  = 'T') L1 ON L1.CustomerId  = c.CustomerId  
INNER JOIN 
    (SELECT
         CustomerId, LeaseType  
     FROM
         Lease 
     WHERE
         LeaseType = 'P') L2 ON L2.CustomerId = c.CustomerId
INNER JOIN 
    (SELECT
         CustomerId, LeaseType  
     FROM
         Lease 
     WHERE
         LeaseType  = 'U') L3 ON L3.CustomerId = c.CustomerId
WHERE 
    CustomerId > 10000