MSSQL 中唯一的字母数字密钥生成

Question

我有用作键的 char(4) 字段的表。生成的值（最大值 + 1）。但它没有达到最大值（9999）。无法更改列的数据类型，因为它在很多地方都使用过。

我想出了一个像下面这样的解决方案...

9999 -> A000...A999->B000...B999->Z999 -> ZA00->ZZZZ（zzzz再用10年就可以了）

请告诉我，除了执行 substring() 和字符串操作之外，还有一种简单的方法来生成它吗？

当前代码：

DECLARE @cle smallint
SELECT @cle = isnull(MAX(CONVERT(smallint,RTRIM(cle))),0) from smnf
INSERT INTO smnf (sup, cle, dsc, exc, dirty) VALUES (@sup, CONVERT(char(4), @cle+1), @dsc, 0, 'A')

Answer 1

SELECT i INTO #t FROM (SELECT '0' i UNION ALL SELECT '1' UNION ALL SELECT '2' UNION ALL SELECT '3' UNION ALL SELECT '4' UNION ALL SELECT '5' UNION ALL SELECT '6' UNION ALL SELECT '7' UNION ALL SELECT '8' UNION ALL SELECT '9' UNION ALL SELECT 'A' UNION ALL SELECT 'B' UNION ALL SELECT 'C' UNION ALL SELECT 'D' UNION ALL SELECT 'E' UNION ALL SELECT 'F' UNION ALL SELECT 'G' UNION ALL SELECT 'H' UNION ALL SELECT 'I' UNION ALL SELECT 'J' UNION ALL SELECT 'K' UNION ALL SELECT 'L' UNION ALL SELECT 'M' UNION ALL SELECT 'N' UNION ALL SELECT 'O' UNION ALL SELECT 'P' UNION ALL SELECT 'Q' UNION ALL SELECT 'R' UNION ALL SELECT 'S' UNION ALL SELECT 'T' UNION ALL SELECT 'U' UNION ALL SELECT 'V' UNION ALL SELECT 'W' UNION ALL SELECT 'X' UNION ALL SELECT 'Y' UNION ALL SELECT 'Z') t

CREATE TABLE id_list (id char(4) PRIMARY KEY);

INSERT id_list
SELECT c1.i+c2.i+c3.i+c4.i
FROM #t c1, #t c2, #t c3, #t c4
WHERE c1.i+c2.i+c3.i+c4.i NOT LIKE '[0-9]%[A-Z]%'  --Eliminate alphas in the first 10000 to preserve existing ids.

当你需要下一个 id 时：

DECLARE @curr_id char(4) = '9ZZZ'
DECLARE @next_id char(4)

SELECT TOP 1 @next_id = [id] FROM id_list WHERE [id] > @curr_id

PRINT @next_id

A000