Question

我有一个有效的MySQL查询，它为给定用户更新或插入数据（多行），与默认用户＆＃39; admin＆＃39;相同。它适用于MySQL，但我很难将其转换为Microsoft SQL Server 2012等效版本。

MySQL查询是：

REPLACE INTO table_name (user, name, sub_name, display, html_div, display_order, good_low, good_high, critical_low, warning_low, warning_high, critical_high, last_updated) 
SELECT 'user1', name, sub_name, display, html_div, display_order, good_low, good_high, critical_low, warning_low, warning_high, critical_high, last_updated 
FROM table_name WHERE user = 'admin'

我尝试将其转换为SQL Server的是：

MERGE table_name AS TARGET
USING (SELECT 'user1', name, sub_name, display, html_div, display_order, good_low, good_high, critical_low, warning_low, warning_high, critical_high, last_updated FROM table_name WHERE [user] = 'admin')
    AS SOURCE ([user], name, sub_name, display, html_div, display_order, good_low, good_high, critical_low, warning_low, warning_high, critical_high, last_updated)
    ON TARGET.[user] = 'admin'
WHEN MATCHED THEN
    UPDATE
    SET [user] = 'user1', name = SOURCE.name, sub_name = SOURCE.sub_name, display = SOURCE.display, html_div = SOURCE.html_div, display_order = SOURCE.display_order, good_low = SOURCE.good_low, good_high = SOURCE.good_high, critical_low = SOURCE.critical_low, warning_low = SOURCE.warning_low, warning_high = SOURCE.warning_high, critical_high = SOURCE.critical_high, last_updated = SOURCE.last_updated
WHEN NOT MATCHED THEN
    INSERT ([user], name, sub_name, display, html_div, display_order, good_low, good_high, critical_low, warning_low, warning_high, critical_high, last_updated)
    VALUES ('user1', SOURCE.name, SOURCE.sub_name, SOURCE.display, SOURCE.html_div, SOURCE.display_order, SOURCE.good_low, SOURCE.good_high, SOURCE.critical_low, SOURCE.warning_low, SOURCE.warning_high, SOURCE.critical_high, SOURCE.last_updated);

我收到错误：

Msg 8672, Level 16, State 1, Line 1
The MERGE statement attempted to UPDATE or DELETE the same row more than once. This happens when a target row matches more than one source row. A MERGE statement cannot UPDATE/DELETE the same row of the target table multiple times. Refine the ON clause to ensure a target row matches at most one source row, or use the GROUP BY clause to group the source rows.

但是查询预计会更新多行，所以我想我需要一些不同的东西。

你能帮我把这个MySQL查询转换成它的等效SQL Server吗？

Answer 1

MERGE要求源行上的唯一值与目标中的行匹配。否则它不知道要使用哪一个源行 - 它们可能不同！在这种情况下，您尚未指定从TARGET到SOURCE的任何匹配。 ON TARGET.[user] = 'admin'应该是ON TARGET.[user] = SOURCE.[user]。每个源行应匹配一个（或多个目标行）。但是每个目标行应该只匹配一个源行。

因此，您在SOURCE中创建“相似”行，然后将用户ID与目标表进行比较。如果用户已经在那里，则重写数据以使其看起来相似。否则插入一个新行。

SQL：如何转换REPLACE INTO .... SELECT .... FROM查询从MySQL到SQL服务器？

1 个答案: