使用这样的临时表，这个查询可能会更快。同时，应该检查这些表所需的索引。

SELECT N.CONS_ID AS CUST_ID,
COUNT(Distinct(Isnull(M.CO_ID,1))) AS CUST_COUNT
Into #Temp
FROM CTS_VIEW.CNSLD_CREDIT_SUM M
INNER JOIN  CTS_VIEW.LEGACY_CODE_XREF  N
ON M.EE_ID = N.EE_GBL_IND
WHERE M.PROD_DT >= DATE '2018-12-31'
GROUP BY N.CONS_ID

select CUST_ID, CUST_COUNT from 

# Temp

where CUST_COUNT>1;

我认为cte或通用表表达式将有助于实现这些目标-

SELECT CUST_ID,CUST_COUNT FROM (
WITH M_RAW_CTE AS 
(SELECT CO_ID,EE_ID,PROD_DT FROM CTS_VIEW.CNSLD_CREDIT_SUM),
M_CTE AS 
(SELECT * FROM M_RAW_CTE WHERE PROD_DT >= DATE '2018-12-31'), 
N_CTE AS 
(SELECT CONS_ID,EE_GBL_IND FROM LEGACY_CODE_XREF) 

SELECT N_CTE.CONSID AS CUST_ID,
COUNT(DISTINCT(ISNULL(M.CO_ID,1))) AS CUST_COUNT
INNER JOIN N_CTE ON M_CTE.EE_ID = N_CTE.EE_GBL_IND
GROUP BY N_CTE.CONS_ID)
WHERE CUST_COUNT > 1;

使用cte背后的概念是增加ddl中数据的可重用性。