解析逗號分隔的字符串，使在字符串列表Where子句

Question

我的存儲過程接收一個參數，它是一個逗號分隔的字符串：

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

我需要它來作此發言：

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

這樣做的最佳做法是什麼？

Answer 1

創建此功能（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 

使用這一說法

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

---

比較荷蘭國際集團我的分裂功能，以XML拆分：

TESTDATA：

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 

這將在每次運行改變，但你想法

Answer 2

嘗試這一個 -

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') 

查詢：

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) 
)) 

輸出：

擴展統計：

SSMS SET STATISTICS TIME + 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. 

CTE：

(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

T他最有效的方法是使用CLR函數進行拆分字符串。請參閱this article的示例和性能比較