sql - 解析逗号分隔的字符串以在 Where 子句中生成 IN 字符串列表

Question

我的存储过程接收到一个以逗号分隔的字符串的参数：

DECLARE @Account AS VARCHAR(200)
SET @Account = 'SA,A'

我需要从中做出这样的声明：

WHERE Account IN ('SA', 'A')

这样做的最佳做法是什么？

Answer 1

创建这个函数（sqlserver 2005+）

CREATE function [dbo].[f_split]
(
@param nvarchar(max), 
@delimiter char(1)
)
returns @t table (val nvarchar(max), seq int)
as
begin
set @param += @delimiter

;with a as
(
select cast(1 as bigint) f, charindex(@delimiter, @param) t, 1 seq
union all
select t + 1, charindex(@delimiter, @param, t + 1), seq + 1
from a
where charindex(@delimiter, @param, t + 1) > 0
)
insert @t
select substring(@param, f, t - f), seq from a
option (maxrecursion 0)
return
end

使用这个语句

SELECT *
FROM yourtable 
WHERE account in (SELECT val FROM dbo.f_split(@account, ','))

---

将我的拆分功能与 XML 拆分进行比较：

测试数据：

select top 100000 cast(a.number as varchar(10))+','+a.type +','+ cast(a.status as varchar(9))+','+cast(b.number as varchar(10))+','+b.type +','+ cast(b.status as varchar(9)) txt into a 
from master..spt_values a cross join master..spt_values b

XML:

 SELECT count(t.c.value('.', 'VARCHAR(20)'))
 FROM (
     SELECT top 100000 x = CAST('<t>' + 
           REPLACE(txt, ',', '</t><t>') + '</t>' AS XML)
           from a
 ) a
 CROSS APPLY x.nodes('/t') t(c)

Elapsed time: 1:21 seconds

f_split：

select count(*) from a cross apply clausens_base.dbo.f_split(a.txt, ',')

Elapsed time: 43 seconds

这会随着运行而变化，但你明白了

Answer 2

试试这个——

DDL：

CREATE TABLE dbo.Table1 (
      [EmpId] INT
    , [FirstName] VARCHAR(7)
    , [LastName] VARCHAR(10)
    , [domain] VARCHAR(6)
    , [Vertical] VARCHAR(10)
    , [Account] VARCHAR(50)
    , [City] VARCHAR(50)
)

INSERT INTO dbo.Table1 ([EmpId], [FirstName], [LastName], [Vertical], [Account], [domain], [City])
VALUES 
     (345, 'Priya', 'Palanisamy', 'DotNet', 'LS', 'Abbott', 'Chennai'),
     (346, 'Kavitha', 'Amirtharaj', 'DotNet', 'CG', 'Diageo', 'Chennai'),
     (647, 'Kala', 'Haribabu', 'DotNet', 'DotNet', 'IMS', 'Chennai')

询问：

DECLARE @Account VARCHAR(200)
SELECT @Account = 'CG,LS'

SELECT *
FROM Table1
WHERE [Vertical] = 'DotNet' AND (ISNULL(@Account, '') = '' OR Account IN (
     SELECT t.c.value('.', 'VARCHAR(20)')
     FROM (
         SELECT x = CAST('<t>' + 
               REPLACE(@Account, ',', '</t><t>') + '</t>' AS XML)
     ) a
     CROSS APPLY x.nodes('/t') t(c)
))

输出：

扩展统计：

SSMS 设置统计时间 + IO：

XML:

(3720 row(s) affected)
Table 'temp'. Scan count 3, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'Worktable'. Scan count 0, logical reads 0, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

 SQL Server Execution Times:
   CPU time = 187 ms,  elapsed time = 242 ms.

热电偶：

(3720 row(s) affected)
Table '#BF78F425'. Scan count 360, logical reads 360, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.
Table 'temp'. Scan count 1, logical reads 7, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

 SQL Server Execution Times:
   CPU time = 281 ms,  elapsed time = 335 ms.

Answer 3

最有效的方法是使用 CLR 函数来拆分字符串。有关示例和性能比较，请参阅本文

Answer 4

SQL Server 2016+ 提供了此处描述的 String_Split：https://www.sqlshack.com/the-string-split-function-in-sql-server/，它非常适合我的目的并且易于使用，例如像这样：

declare @InClauesQueryString nvarchar(100) = '1,2'; 
declare @exampleTable table(ID int,Val nvarchar(100));
INSERT INTO @exampleTable (ID, Val) VALUES (1,'test1');
INSERT INTO @exampleTable (ID, Val) VALUES (2,'test2');
select * from @exampleTable where id in (select * from string_split(@InClauesQueryString,','));