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通常存在这样一种情况，例如，Web 表单输入会产生多个长度相同的数组，其中每个数组都是不同的变量，需要包含在查询的特定部分中。假设你有...

set @transforms = "a,b,c"; set @bys = "colX,colY,colZ";

……你想要……

+------+---+------+
| row  | x | x    |
+------+---+------+
|    1 | a | colX |
|    2 | b | colY |
|    3 | c | colZ |
+------+---+------+

是否有这样做的最佳实践，或者至少有此类问题的名称？据我所知，它可能已经是 ArtfulSoftware 上的示例之一，我只是不知道要查找什么标题。我能想到的最好的代码是下面的代码，但感觉就像我在重新发明轮子，我宁愿以真正知道自己在做什么的人喜欢的任何方式来做。有什么建议么？谢谢。

DELIMITER ##
DROP PROCEDURE IF EXISTS twoarrays ##
CREATE PROCEDURE hs.twoarrays
-- example usage: 
-- call twoarrays('array1','array2','delim1','delim2')
(
        IN array1   VARCHAR(2000),
        IN array2   VARCHAR(2000),
        IN delim1   VARCHAR(10),
        IN delim2   VARCHAR(10)
)
BEGIN
    IF delim1 is NULL THEN SET delim1 = ','; END IF;
    IF delim2 is NULL THEN SET delim2 = delim1; END IF;
    set @@group_concat_max_len = 99999;
    select @foo := concat("select @rowa := @rowa + 1 as row, '",
        replace(array1,delim1,"' x union select @rowa := @rowa + 1,'"),
        "' from (select @rowa := 0) r");
    select @bar := concat("select @rowb := @rowb + 1 as row, '",
        replace(array2,delim2,"' x union select @rowb := @rowb + 1,'"),
        "' from (select @rowb := 0) r");
    select @baz := concat("select a.*,b.x from (",
        @foo,
        ") a join (",
        @bar,
        ") b on a.row = b.row");
prepare twoarrayproc from @baz;
execute twoarrayproc;
END ## 
DELIMITER ; 

call twoarrays(@transforms,@bys,NULL,NULL);
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