生成3位的序列号_仅仅CASE WHEN的简单应用

 1 SELECT TOP 200
 2     PNo, IDENTITY( INT,1,1 ) AS sn
 3 INTO
 4     #temp1
 5 FROM
 6     tbl_test 
 7 
 8 SELECT
 9     CASE WHEN sn < 10 THEN '00' + CONVERT(CHAR(1), sn)
10          WHEN sn >= 10
11               AND sn <= 99 THEN '0' + CONVERT(CHAR(2), sn)
12          WHEN sn >= 100 THEN CONVERT(CHAR(3), sn)
13     END AS sn, PNo
14 FROM
15     #temp1
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原文地址：https://www.cnblogs.com/bamboo-140/p/9810795.html