我对一个表有一个简单的查询，它返回如下结果：
id id_type id_ref
2702 5 31
2702 16 14
2702 17 3
2702 40 1
2703 23 4
2703 23 5
2703 34 6
2704 1 14
我想将结果合并到一行中，例如：
id concatenation
2702 5,16,17,40:31,14,3,1
2703 23,23,34:4,5,6
2704 1:14
有没有办法在触发器中做到这一点？
注意：我知道我可以使用光标，但除非没有更好的方法，否则我真的不想这样做。
数据库是 Sybase 版本 12.5.4。
【问题讨论】：
使用行级函数。
您的查询：
select distinct id ,fn(id) from table1
功能：
fn(@id int)
(
declare @res varchar
select @res = @res+id_ref+"," from table1 where id=@id
return @res
)
【讨论】：
由于在 Sybase 中使用 select 语句来完成这项工作相当困难，我建议使用类似以下的 while 循环。 While 循环比游标更受欢迎，因为它更快。假设表名是 MYTABLE：
CREATE TABLE #temp
(
aa numeric(5,0) identity,
id int not null,
id_type int not null,
id_ref int not null
)
CREATE TABLE #results
(
id int not null,
concatenation varchar(1000) not null,
)
insert into #temp
select id, id_type, id_ref from MYTABLE order by id
declare @aa int, @maxaa int, @idOld int, @idNew int
declare @str1 varchar(1000), @str2 varchar(1000)
set @aa = 1
set @maxaa = (select max(aa) from #temp)
set @idNew = (select id from #temp where aa = 1)
, @idOld = @idNew
while @aa <= @maxaa
begin
set @idNew = (select id from #temp where aa = @aa)
IF @idNew = @idOld
BEGIN
set @str1 = @str1 + convert(varchar,(select id_type from #temp where aa = @aa)) + ','
, @str2 = @str2 + convert(varchar,(select id_ref from #temp where aa = @aa)) + ','
IF @aa = @maxaa
insert into #results (id, concatenation)
VALUES (@idOld, left(@str1,len(@str1) - 1) + ':' + left(@str2,len(@str2) - 1) )
END
ELSE
BEGIN
insert into #results (id, concatenation)
VALUES (@idOld, left(@str1,len(@str1) - 1) + ':' + left(@str2,len(@str2) - 1) )
set @str1 = NULL, @str2 = NULL
set @str1 = @str1 + convert(varchar,(select id_type from #temp where aa = @aa)) + ','
, @str2 = @str2 + convert(varchar,(select id_ref from #temp where aa = @aa)) + ','
IF @aa = @maxaa
insert into #results (id, concatenation)
VALUES (@idNew, left(@str1,len(@str1) - 1) + ':' + left(@str2,len(@str2) - 1) )
END
set @idOld = @idNew
set @aa = @aa+1
end
select * from #results
编辑 以下版本快 45% 左右
CREATE TABLE #temp
(
aa numeric(5,0) identity,
id int not null,
id_type int not null,
id_ref int not null
)
CREATE TABLE #results
(
id int not null,
concatenation varchar(1000) not null,
)
insert into #temp
select id, id_type, id_ref from MYTABLE order by id
declare @aa int, @maxaa int, @idOld int, @idNew int
declare @str1 varchar(1000), @str2 varchar(1000), @j int
set @aa = 1
set @maxaa = (select max(aa) from #temp)
set @idNew = (select id from #temp where aa = 1)
, @idOld = @idNew
set @str1 = ':'
while @aa <= @maxaa
begin
set @idNew = (select id from #temp where aa = @aa)
IF @idNew = @idOld
BEGIN
set @str2 = (select convert(varchar,id_type) + ':' + convert(varchar,id_ref) from #temp where aa = @aa)
set @j = (select charindex(':',@str2))
set @str1 = str_replace(@str1, ':', substring(@str2,1,@j - 1) + ',:') + right(@str2,len(@str2) - @j) + ','
IF @aa = @maxaa
insert into #results (id, concatenation)
VALUES (@idOld, left(str_replace(@str1, ',:', ':'),len(@str1) - 2) )
END
ELSE
BEGIN
insert into #results (id, concatenation)
VALUES (@idOld, left(str_replace(@str1, ',:', ':'),len(@str1) - 2) )
set @str1 = ':'
set @str2 = (select convert(varchar,id_type) + ':' + convert(varchar,id_ref) from #temp where aa = @aa)
set @j = (select charindex(':',@str2))
set @str1 = str_replace(@str1, ':', substring(@str2,1,@j - 1) + ',:') + right(@str2,len(@str2) - @j) + ','
IF @aa = @maxaa
insert into #results (id, concatenation)
VALUES (@idNew, left(str_replace(@str1, ',:', ':'),len(@str1) - 2) )
END
set @idOld = @idNew
set @aa = @aa+1
end
select * from #results
【讨论】：
好的，如果我在这里遗漏了一些重要的东西，请原谅我，因为我对 Sybase 的第一件事一无所知。但是在 mysql 中，这非常简单，所以我认为它不会像到目前为止的答案那么糟糕。因此，从可能相关或不相关的文档中提取：
SELECT id, LIST(id_type) + ":" + LIST(id_ref) AS concatentation
如果我读错了什么，请告诉我，我会删除它。
【讨论】：
我没有要测试的sybase 服务器，但是在线阅读文档，似乎支持公用表表达式。我不确定其他解决方案中使用的 ROW_NUMBER，所以这里有一个不使用它的解决方案。
我相信 sybase 使用 ||对于字符串连接，尽管我阅读的文档提到也可以使用“+”，所以我使用了它。请酌情更改。
我已对查询进行了评论，试图解释发生了什么。
查询连接所有具有相同 id 的 id_type 和 id_ref 值，以“id_type”递增的顺序。
/* a common table expression is used to concatenate the values, one by one */
WITH ConcatYourTable([id], /* the id of rows being concatenated */
concat_id_type, /* concatenated id_type so far */
concat_id_ref, /* concatenated id_ref so far */
last_id_type, /* the last id_type added */
remain) /* how many more values are there to concatenate? */
AS
(
/* start with the lowest id_type value for some id */
SELECT id, id_type, id_ref,
id_type, /* id_type was concatentated (it's presently the only value) */
(SELECT COUNT(*) FROM YourTable f2 WHERE f2.id=f.id)-1
/* how many more values to concatenate -1 because we've added one already */
FROM YourTable f
WHERE NOT EXISTS
/* start with the lowest value - ensure there are no other values lower. */
(SELECT 1 FROM YourTable f2 WHERE f2.id=f.id AND f2.id_type<f.id_type)
UNION ALL
/* concatenate higher values of id_type for the same id */
SELECT f.id,
c.id_type + ',' + f.id_type, /* add the new id_type value to the current list */
c.id_ref + ',' + f.id_ref, /* add the new id_ref value to the current list */
f.id_type, /* the last value added - ensured subsequent added values are greater */
c.remain-1 /* one less value to add */
FROM ConcatYourTable c /* take what we have concatenated so far */
INNER JOIN YourTable f /* add another row with the same id, and > id_type */
ON f.id = c.id AND f.id_type > c.last_id_type
/* we really want the next highest id_type, not just one that is greater */
WHERE NOT EXISTS (SELECT 1 FROM YourTable f2
WHERE f2.id=f.id AND f2.id_type<f.id_type AND
f2.id_type>c.last_id_type)
)
/* Select the rows where all values for and id were concatenated (remain=0) */
/* Concatenate the cumulated id_type and id_ref fields to format id_type values:id_ref values*/
SELECT id, id_type+':'+id_ref FROM ConcatYourTable
WHERE remain=0
该查询非常“野蛮”，因为它没有使用可能会提高可读性或性能的更复杂的功能。我之所以这样做，是因为我不太了解 sybase，并且使用了我有理由相信的那些特性是受支持的。为获得最佳性能，请确保 id 和 (id,id_type) 已编入索引。
要在触发器（例如 INSERT 或 UPDATE 触发器）中使用它来维护基于此连接查询的表，请扩展基本案例的 WHERE 子句（在 UNION ALL 之前）以包含 id=@changed_id。这将确保只计算更改后的 id 的连接行。然后，您可以使用计算的连接行做您想做的事情。如果要将串联查询具体化到表中，则删除表中@changed_id 的当前串联行，并从上述串联查询的结果中插入新行。您还可以检查您的连接表是否已经包含一个带 changed_id 的值，并改用 UPDATE 语句。
【讨论】：
另一种适用于 Sybase ASE 12.5.4 的方法。该表必须在 id 上具有聚集索引，才能使其正常工作。假设表名是 MYTABLE：
declare @strNew varchar(10), @strOld varchar(10), @str1 varchar(1000), @str2 varchar(1000)
set @str1 = NULL, @str2 = NULL, @strNew = NULL, @strOld = NULL
UPDATE MYTABLE
SET @strNew = convert(varchar,id)
, @str1 = case when @strNew = @strOld then @str1 + convert(varchar,id_type) + "," else @str1 + '$' + @strNew + '$' + convert(varchar,id_type) + "," end
, @str2 = case when @strNew = @strOld then @str2 + convert(varchar,id_ref) + "," else @str2 + '$' + @strNew + '$' + convert(varchar,id_ref) + "," end
, @strOld = convert(varchar,id)
select id, substring(@str1,charindex("$" + convert(varchar,id) + "$",@str1) + len("$" + convert(varchar,id) + "$"),
case when
charindex(",$",substring(@str1,charindex("$" + convert(varchar,id) + "$",@str1) + len("$" + convert(varchar,id) + "$") + 1,len(@str1)))
= 0 then len(@str1) - (charindex("$" + convert(varchar,id) + "$",@str1) + len("$" + convert(varchar,id) + "$"))
else
charindex(",$",substring(@str1,charindex("$" + convert(varchar,id) + "$",@str1) + len("$" + convert(varchar,id) + "$") + 1,len(@str1)))
end
)
+ ':' +
substring(@str2,charindex("$" + convert(varchar,id) + "$",@str2) + len("$" + convert(varchar,id) + "$"),
case when
charindex(",$",substring(@str2,charindex("$" + convert(varchar,id) + "$",@str2) + len("$" + convert(varchar,id) + "$") + 1,len(@str2)))
= 0 then len(@str2) - (charindex("$" + convert(varchar,id) + "$",@str2) + len("$" + convert(varchar,id) + "$"))
else
charindex(",$",substring(@str2,charindex("$" + convert(varchar,id) + "$",@str2) + len("$" + convert(varchar,id) + "$") + 1,len(@str2)))
end
) as concatenation
from MYTABLE
group by id
【讨论】：
print "%1!:%2!",@str1,@str2。随后的 select 语句根据id 的值提取这些字符串的适当子字符串。必须小心计算正确的长度。需要case 语句，因为在最后一个子字符串之后不再有,$，它表示子字符串的结尾。希望对您有所帮助。
我现在能想到的最好的是下一个：
select a.id id,
str (a.id_type,4,0)||
','||str (b.id_type,4,0)||
','||str (c.id_type,4,0)||
','||str (d.id_type,4,0)||
','||str (e.id_type,4,0)||':'||
str (a.id_ref,4,0)||
','||str (b.id_ref,4,0)||
','||str (c.id_ref,4,0)||
','||str (d.id_ref,4,0)||
','||str (e.id_ref,4,0) concatenation
from dbo.merge_test a,
dbo.merge_test b,
dbo.merge_test c,
dbo.merge_test d,
dbo.merge_test e
where a.id = b.id
and a.id = b.id
and a.id = c.id
and a.id = d.id
and a.id = e.id
and a.id_type < b.id_type
and b.id_type <c.id_type
and c.id_type < d.id_type
and d.id_type < e.id_type
但是结果和你输入的有点不同……！！！
【讨论】：
这里有一个解决方案：
SELECT DISTINCT
id,
concatenation = LEFT(id_types, LEN(id_types) - 1) + ':' + LEFT(id_refs, LEN(id_refs) - 1)
FROM (
SELECT id,
id_types = (SELECT CAST(b.id_type AS nvarchar) + ',' FROM Table1 b WHERE b.id = a.id FOR XML PATH('')),
id_refs = (SELECT CAST(c.id_ref AS nvarchar) + ',' FROM Table1 c WHERE c.id = a.id FOR XML PATH(''))
FROM Table1 a
) t
更新：另一种方法
;WITH r(id, rnk, id_type, id_ref) AS
(
SELECT id,
rnk = ROW_NUMBER() OVER(ORDER BY id),
id_type = CAST(id_type AS nvarchar(MAX)),
id_ref = CAST(id_ref AS nvarchar(MAX))
FROM Table1
), anchor(id, rnk, id_type, id_ref) AS
(
SELECT id,
rnk,
id_type,
id_ref
FROM r
WHERE rnk = 1
), result(id, rnk, id_type, id_ref) AS
(
SELECT id,
rnk,
id_type,
id_ref
FROM anchor
UNION ALL
SELECT r.id,
r.rnk,
result.id_type + ',' + r.id_type,
result.id_ref + ',' + r.id_ref
FROM r
INNER JOIN result ON r.id = result.id AND r.rnk = result.rnk + 1
)
SELECT id, concatenation = MAX(id_type) + ':' + MAX(id_ref)
FROM result
GROUP BY id
【讨论】：