Question

我想创建一个动态更新查询，我需要在列中设置一个特定的值。但是列名需要从另一个表中选择。我已经有以下查询：

UPDATE core.TableRes
SET (
    SELECT Code FROM core.TableFields 
    INNER JOIN core.TableXTableFields ON TableXTableFields.FieldID = TableFields.FieldID 
    INNER JOIN core.TableResRefLinks ON TableResRefLinks.ExtraFieldID = TableXTableFields.ExtraFieldID 
    WHERE TableResRefLinks.TableResRefLinksID = RefLinks.TableResRefLinksID)
= (
    SELECT Value FROM core.TableResRefLinks WHERE TableResRefLinksID = RefLinks.TableResRefLinksID)
FROM core.TableRes
    INNER JOIN core.TableResRefLinks RefLinks ON RefLinks.ResourceID = TableRes.ResourceID
    INNER JOIN core.TableXTableFields ON TableXTableFields.ExtraFieldID = RefLinks.ExtraFieldID
    INNER JOIN core.TableFields ON TableFields.FieldID = TableXTableFields.FieldID
    WHERE (EndDate IS NULL OR EndDate > GETDATE()) AND
    (
        SELECT Code FROM core.TableFields 
        INNER JOIN core.TableXTableFields ON TableXTableFields.FieldID = TableFields.FieldID 
        INNER JOIN core.TableResRefLinks ON TableResRefLinks.ExtraFieldID = TableXTableFields.ExtraFieldID 
        WHERE TableResRefLinks.TableResRefLinksID = RefLinks.TableResRefLinksID) 
    <>
    (
        SELECT Value FROM core.TableResRefLinks 
        WHERE TableResRefLinksID = RefLinks.TableResRefLinksID)

它给了我以下错误：

Msg 102, Level 15, State 1, Line 2
Incorrect syntax near '('.
Msg 102, Level 15, State 1, Line 3
Incorrect syntax near '='.
Msg 156, Level 15, State 1, Line 5
Incorrect syntax near the keyword 'FROM'.
Msg 102, Level 15, State 1, Line 14
Incorrect syntax near '<'.

有没有办法解决这个问题？如果我更改完整的UPDATE和SET语句并用SELECT *替换它们，我会得到结果。

EDIT
以下是数据类型
TableFields.Code =＆gt;为nvarchar（100）
TableResRefLinks.Value =＆gt; SQL_VARIANT
并且将列名为TableFields.Code的列的数据类型设置为sql_variant

Answer 1

使用纯SQL无法解决此问题。您需要某种脚本来构建语句。例如，postgresql有一个名为“pgpsql”的脚本语言，它允许构建动态SQL语句。但这显然取决于底层的RDBMS。

顺便说一下：当你进行简单的子选择时，这适用于SELECT。

动态UPDATE语句

1 个答案: