如何编写此查询以获得更好的性能？
SELECT T1.flow
FROM #allflows T1 INNER JOIN
#allflows T2
ON t2.flow like t1.flow + '%'
我通过查询样本客户表（30,000 行）制作了自己的代表“#allflows”
这是我得到的
Declare @s as datetime = getdate();
CREATE NONCLUSTERED INDEX ix_tempNCIndexAft ON #allflows (flow);
SELECT 'make index', DATEDIff(second,@s, getdate())
SET @s = getdate();
SELECT t1.flow,COUNT(DISTINCT t2.flow) cnt INTO #realflows FROM #allflows t1
INNER JOIN #allflows t2 ON t2.flow like t1.flow+ '%' GROUP BY t1.flow HAVING COUNT(DISTINCT t2.flow) = 1;
SELECT 'your query', DATEDIff(second,@s, getdate())
select * from #realflows ;
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我来说两句