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)
