sql – Oracle合并对选择然后插入或更新

什么是更快？

合并声明

MERGE INTO table_name 
     USING dual
     ON (row_id = 'some_id')
    WHEN MATCHED THEN
     UPDATE SET col_name = 'some_val'
    WHEN NOT MATCHED THEN
     INSERT (row_id,col_name)
     VALUES ('some_id','some_val')

要么

查询select语句,然后使用update或insert语句.

SELECT * FROM table_name where row_id = 'some_id'

如果rowCount == 0

INSERT INTO table_name (row_id,col_name) VALUES ('some_id','some_val')

其他

UPDATE table_name SET col_name='some_val' WHERE row_id='some_id'

解决方法

经验法则是,如果您可以在一个sql中执行此操作,则通常会在多个sql语句中执行更好.

如果这样做,我会和MERGE一起去.

另外 – 另一个建议：你可以避免在你的声明中重复数据,例如：

MERGE INTO table
 USING (SELECT 'some_id' AS newid,'some_val' AS newval
        FROM dual)
 ON (rowid = newid)
WHEN MATCHED THEN
 UPDATE SET colname = newval
WHEN NOT MATCHED THEN
 INSERT (rowid,colname)
 VALUES (newid,newval)