WHEN MATCHED THEN operation WHEN NOT MATCHED THEN operation; 注意:其中最后语句分号不可以省略,且源表既可以是一个表也可以是一个子查询语句。 MERGE的用法 merge无法多次更新同一行,也无法更新和删除同一行。 当源表和目标表不匹配时: 若数据是源表有目标表没有,则进行插入操作; 若数据是源表没有而目标表...
WHEN MATCHED THEN operation WHEN NOT MATCHED THEN operation; 注意:其中最后语句分号不可以省略,且源表既可以是一个表也可以是一个子查询语句。 MERGE的用法 merge无法多次更新同一行,也无法更新和删除同一行 当源表和目标表不匹配时: 若数据是源表有目标表没有,则进行插入操作; ...
The join operation in the MERGE statement is optimized in the same way as a join in a SELECT statement. That is, when SQL Server processes join, the query optimizer chooses the most efficient method (out of several possibilities) of processing the join. When the source and target are of ...
Now that the database is ready, the next step I am going to perform is to apply the MERGE statement and try to get both the tables to synchronize with each other. The first operation that we are trying to see is how to manage the INSERTs. You can copy and paste the below SQL code...
This operation cascades to associated instances if the association is mapped withcascade="merge". SeeMergingfor a detailed discussion of merging. Changed in version 1.1: -Session.merge()will now reconcile pending objects with overlapping primary keys in the same way as persistent. SeeSession.merge ...
operation; 1. 2. 3. 4. 5. 6. 7. 注意:其中最后语句分号不可以省略,且源表既可以是一个表也可以是一个子查询语句。 MERGE的用法 merge无法多次更新同一行,也无法更新和删除同一行 当源表和目标表不匹配时: 若数据是源表有目标表没有,则进行插入操作; ...
(updatesDF.selectExpr("updates.customerId as mergeKey","*")// Rows for 2.)// Apply SCD Type 2 operation using mergecustomersTable.as("customers").merge(stagedUpdates.as("staged_updates"),"customers.customerId = mergeKey").whenMatched("customers.current = true AND customers.address <> ...
According to the SQL semantics of merge, this type of update operation is ambiguous because it is unclear which source row should be used to update the matched target row. You can preprocess the source table to eliminate the possibility of multiple matches. See the change data capture example....
According to the SQL semantics of merge, this type of update operation is ambiguous because it is unclear which source row should be used to update the matched target row. You can preprocess the source table to eliminate the possibility of multiple matches. See the change data capture exampl...
MERGE关键字是一个神奇的DML关键字,它能将INSERT,UPDATE,DELETE等操作并为一句,根据与源表联接的结果,对目标表执行插入、更新或删除操作。 MERGE的语法 MERGE INTO target_table USING source_table ON condition WHEN MATCHED THEN operation WHEN NOT MATCHED THEN ...