關(guān)于拼接字符串的一個(gè)細(xì)節(jié)問題
作者:思想瞭望者
本文主要介紹了我們?cè)诶肧QL語(yǔ)句拼接帶分隔符的字符串時(shí)的一個(gè)細(xì)節(jié)問題以及解決方案,希望能夠?qū)δ兴鶐椭?/div>
在SQL Server數(shù)據(jù)庫(kù)中,我們可能會(huì)因?yàn)楣ぷ鞯男枰?,必?strong>拼接字符串。好多朋友喜歡這樣拼接字符串(SQL Server 2008 R2,CTE部分是偽造的示例數(shù)據(jù)):
- WITH TEMP AS
- (
- SELECT 'A' AS ITEM
- UNION ALL
- SELECT 'B' AS ITEM
- UNION ALL
- SELECT 'C' AS ITEM
- )
- SELECT A.ITEM+',' AS [data()]
- FROM TEMP A
- FOR XML PATH('')
這個(gè)QUERY會(huì)得到這樣的XML:
A, B, C,
但是潛在的問題是當(dāng)數(shù)據(jù)不是字符型的時(shí)候會(huì)出問題,試把CTE中的數(shù)據(jù)全部改為數(shù)字。
- WITH TEMP AS
- (
- SELECT 1 AS ITEM
- UNION ALL
- SELECT 2 AS ITEM
- UNION ALL
- SELECT 3 AS ITEM
- )
- SELECT A.ITEM+',' AS [data()]
- FROM TEMP A
- FOR XML PATH('')
這個(gè)QUERY會(huì)報(bào)錯(cuò):
Msg 245, Level 16, State 1, Line 2 Conversion failed when converting the varchar value ',' to data type int.
所以,我推薦的拼接方式是:
- WITH TEMP AS
- (
- SELECT 1 AS ITEM
- UNION ALL
- SELECT 2 AS ITEM
- UNION ALL
- SELECT 3 AS ITEM
- )
- SELECT A.ITEM AS [data()],','
- FROM TEMP A
- FOR XML PATH('')
運(yùn)行結(jié)果是:
1,2,3,
關(guān)于SQL Server數(shù)據(jù)庫(kù)拼接字符串的問題就介紹這么多,如果要了解更多SQL Server數(shù)據(jù)庫(kù)的問題,可以到這里來:http://database.51cto.com/sqlserver/,謝謝大家的支持!
【編輯推薦】
責(zé)任編輯:趙鵬
來源:
博客園


相關(guān)推薦
2011-07-11 16:00:22
2011-07-11 15:36:44
2020-09-18 14:23:50




