sql-server - 如何在 `ntext` 列上使用 `modify` 方法而不将列类型更改为 `xml`(使用 CAST 或 CONVERT 或其他方法)
问题描述
我需要更新存储在ntext
名为的列中的 XML 内容中的两个属性data
我尝试在列上使用或使用xml.modify
XQuery 方法,但没有成功:CAST
CONVERT
data
尝试使用时CAST
UPDATE [dbo].[CodeSystemCodes_data]
SET
(CAST([data] as xml)).modify('replace value of (/Utilities.CodeSystems.CodeSystemCodes/@Description)[1] with sql:variable("@NEW_EXAM_NAME")')
WHERE [data] like '%' + @CURRENT_EXAM_CODE + '%'
我收到这个错误
Incorrect syntax near '('
...在 CAST 之前,删除 '(' 也失败了
我最终创建了一个具有单一XML
类型列的临时表,xmlData
在该表上使用了 modify 方法,然后将数据返回到原始表,但这似乎有点过头了
如何在不使用任何中间表的情况下使用使用类型列的modify
方法?也许与 CAST 或 CONVERT 或其他东西。我尝试使用和 XML 变量也没有成功。data
ntext
请记住,此时无法更改列类型,因为我不是 DBA 或具有决定该角色的人。
我使用 XML 修改方法而不是 REPLACE,因为我不希望沿 XML 数据进行错误替换。
还有其他类似的问题,但目前都没有答案
代码:
DECLARE @NEW_EXAM_NAME NVARCHAR(10) = 'BCC'
DECLARE @CODE_DESC NVARCHAR(50)
SET @CODE_DESC = @CURRENT_EXAM_CODE + ' - ' + @NEW_EXAM_NAME
CREATE TABLE #temp_xml (xmlData XML)
INSERT INTO #temp_xml
SELECT CAST([data] AS XML)
FROM [dbo].[CodeSystemCodes_data]
WHERE [data] LIKE '%' + @CURRENT_EXAM_CODE + '%'
UPDATE #temp_xml
SET xmlData.modify('replace value of (/Utilities.CodeSystems.CodeSystemCodes/@Description)[1] with sql:variable("@NEW_EXAM_NAME")')
UPDATE #temp_xml
SET xmlData.modify('replace value of (/Utilities.CodeSystems.CodeSystemCodes/@CodeAndDescription)[1] with sql:variable("@CODE_DESC")')
SELECT * FROM #temp_xml
UPDATE [dbo].[CodeSystemCodes_data]
SET [data] = CAST(CAST((SELECT xmlData FROM #temp_xml) as nvarchar(max)) as ntext)
WHERE [data] LIKE '%' + @CURRENT_EXAM_CODE + '%'
DROP TABLE #temp_xml
解决方案
不幸的是,当您将 XML 存储为文本时,您几乎被困在做类似的事情。
如果你想摆脱临时表的使用,你可以尝试这样的事情。您可以在 SSMS 中运行它。
/* Base table mock-up */
DECLARE @Data TABLE ( [data] NTEXT, [id] INT IDENTITY (1,1) );
INSERT INTO @Data ( [data] ) VALUES
( '<root><values><val>Value 1</val><val>to_be_changed</val></values></root>' ),
( '<root><values><val>All is well here.</val><val>All is well here, too.</val></values></root>' ),
( '<root><values><val>Another value.</val><val>to_be_changed</val></values></root>' );
/* Find/Replace variables */
DECLARE
@find_value VARCHAR(50) = 'to_be_changed',
@replace_value VARCHAR(50) = 'Value 2';
/* Create a table variable to temporarily house the ntext data as xml so the XML may be modified */
DECLARE @Temp TABLE ( DataXml XML, id INT );
/* Insert [data] into the XML column */
INSERT INTO @Temp ( DataXml, [id] )
SELECT CAST ( [data] AS XML ), [id] FROM @Data WHERE [data] LIKE '%' + @find_value + '%';
/* Show the @Data resultset before modifying */
SELECT * FROM @Data;
/* The WHILE is to make sure every node that requires updating gets updated */
/* Modify each instance matching the @find_value criteria */
WHILE EXISTS ( SELECT * FROM @Temp WHERE DataXml.exist( '//root/values/val/text()[.=sql:variable("@find_value")]' ) = 1 )
UPDATE @Temp
SET
DataXml.modify ('
replace value of (/root/values/val/text()[.=sql:variable("@find_value")])[1]
with sql:variable("@replace_value")
');
/* Update the results back to the ntext column */
UPDATE @Data
SET
[data] = CAST ( t.DataXml AS NVARCHAR(MAX) )
FROM @Data d
INNER JOIN @Temp t
ON d.id = t.id;
/* Show the updated @Data resultset */
SELECT * FROM @Data;
@Data 的初始选择:
/* Show the @Data resultset before modifying */
SELECT * FROM @Data;
退货
+---------------------------------------------------------------------------------------------+----+
| data | id |
+---------------------------------------------------------------------------------------------+----+
| <root><values><val>Value 1</val><val>to_be_changed</val></values></root> | 1 |
| <root><values><val>All is well here.</val><val>All is well here, too.</val></values></root> | 2 |
| <root><values><val>Another value.</val><val>to_be_changed</val></values></root> | 3 |
+---------------------------------------------------------------------------------------------+----+
@Data 的最终结果集:
/* Show the updated @Data resultset */
SELECT * FROM @Data;
退货
+---------------------------------------------------------------------------------------------+----+
| data | id |
+---------------------------------------------------------------------------------------------+----+
| <root><values><val>Value 1</val><val>Value 2</val></values></root> | 1 |
| <root><values><val>All is well here.</val><val>All is well here, too.</val></values></root> | 2 |
| <root><values><val>Another value.</val><val>Value 2</val></values></root> | 3 |
+---------------------------------------------------------------------------------------------+----+
可能的替代方法:
也许REPLACE
对您的文字简单。
UPDATE @Data
SET
[data] = REPLACE ( CAST ( [data] AS NVARCHAR(MAX) ), @find_value, @replace_value )
FROM @Data d
WHERE
d.[data] LIKE '%' + @find_value + '%';
更新:
我应该更清楚地说“我不想使用任何类型的中间表”
/* For-each find/replace instance found... */
WHILE EXISTS ( SELECT * FROM @Data WHERE CAST ( [data] AS XML ).exist( '//root/values/val/text()[.=sql:variable("@find_value")]' ) = 1 )
BEGIN
DECLARE @id INT, @xml XML;
SELECT TOP 1
@id = id,
@xml = CAST ( [data] AS XML )
FROM @Data
WHERE CAST ( [data] AS XML ).exist( '//root/values/val/text()[.=sql:variable("@find_value")]' ) = 1;
-- Modify the XML --
SET @xml.modify('
replace value of (/root/values/val/text()[.=sql:variable("@find_value")])[1]
with sql:variable("@replace_value")
');
-- Update the modified XML --
UPDATE @Data
SET
[data] = CAST ( @xml AS NVARCHAR(MAX) )
WHERE id = @id;
END
/* Show the updated resultset */
SELECT * FROM @Data ORDER BY id;
更新的结果集:
+---------------------------------------------------------------------------------------------+----+
| data | id |
+---------------------------------------------------------------------------------------------+----+
| <root><values><val>Value 1</val><val>Value 2</val><val>Value 2</val></values></root> | 1 |
| <root><values><val>All is well here.</val><val>All is well here, too.</val></values></root> | 2 |
| <root><values><val>Another value.</val><val>Value 2</val></values></root> | 3 |
+---------------------------------------------------------------------------------------------+----+
由 OP 更新
感谢您的最后一个解决方案,我最终这样做了,不需要while循环
DECLARE @CURRENT_EXAM_CODE NVARCHAR(10) = 'BXC_14B'
DECLARE @NEW_EXAM_NAME NVARCHAR(10) = 'BCC'
DECLARE @CODE_DESC NVARCHAR(50)
DECLARE @XML_DATA XML
-- convert existing NTEXT data into XML
SELECT @XML_DATA =
CAST([data] as xml)
FROM [dbo].[CodeSystemCodes_data]
WHERE [data] like '%' + @CURRENT_EXAM_CODE + '%'
-- update the xml data
SET @XML_DATA.modify('replace value of (/Utilities.CodeSystems.CodeSystemCodes/@Description)[1] with sql:variable("@NEW_EXAM_NAME")')
SET @CODE_DESC = @CURRENT_EXAM_CODE + ' - ' + @NEW_EXAM_NAME
SET @XML_DATA.modify('replace value of (/Utilities.CodeSystems.CodeSystemCodes/@CodeAndDescription)[1] with sql:variable("@CODE_DESC")')
-- convert xml data back to ntext type
UPDATE [dbo].[CodeSystemCodes_data]
SET
[data] = CAST(CAST(@XML_DATA as nvarchar(max)) as ntext)
WHERE [data] like '%' + @CURRENT_EXAM_CODE + '%'
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