問題描述
如何將字符串轉換為 XML 數據類型，以便我可以將數據作為 XML 查詢:
How do I convert a string into an XML datatype so that I can query the data as XML:
例如(感謝mellamokb the Wise"為此提供了原始 SQL)
For example (thanks to "mellamokb the Wise" who provided the original SQL for this)
如果 xmlstring 是 XML 類型，則下面的代碼可以正常工作(請參閱 DEMO)
The code below works fine if xmlstring is of the type XML (see DEMO)
select id, name
from Data
cross apply (
select Destination.value('data(@Name)', 'varchar(50)') as name
from [xmlstring].nodes('/Holidays/Summer/Regions/Destinations/Destination') D(Destination)
) Destinations(Name)
但是，如果 xmlString 是 varchar 類型，即使我將字符串轉換為 XML，我也會收到錯誤消息 (演示):
However, if xmlString is of type varchar I get an error even though I'm converting the string to XML (DEMO):
select id, name
from Data
cross apply (
select Destination.value('data(@Name)', 'varchar(50)') as name
from CONVERT(xml,[xmlstring]).nodes('/Holidays/Summer/Regions/Destinations/Destination') D(Destination)
) Destinations(Name)
推薦答案
您可以在一個額外的交叉應用中進行轉換.
You can do the cast it in one extra cross apply.
select id,
T.N.value('@Name', 'varchar(50)') as name
from Data
cross apply (select cast(xmlstring as xml)) as X(X)
cross apply X.X.nodes('/Holidays/Summer/Regions/Destinations/Destination') T(N)
SQL 小提琴
轉換為 XML 可能存在性能問題.看看這個答案和這個答案
There might be performance issues with casting to XML. Have a look at this answer and this answer
這篇關于在 T-SQL 中查詢之前將字符串轉換為 XML 數據類型的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！