Update newly added field from previous record in MySql

Question

I have a table with share prices of different companies for each date. The fields are

 Date | Symbol | Closing_Rate. 

Now I have added one more field to this table Previous Day Closing Rate.

Date | Symbol | Closing_Rate | Pre_Cls_Rate

Please help me for a query to update the previous date's closing rate to current date's field named "Pre_Cls_Rate" Thanks in advance

Answer 1

正如Strawberry所说，这是一种冗余，您无需添加新列即可从同一张表中获取另一行的数据，只需在要获取诸如以下内容的数据时更改查询：

select t1.*,t2.Closing_Rate as Pre_Cls_Ratefrom yourTable t1 inner JOIN yourTable t2 where t1.Symbol=t2.Symbol and t2.Date <= DATE(DATE_SUB(t1.Date, INTERVAL 1 DAY)`) and t2.Date > DATE(DATE_SUB(t1.Date, INTERVAL 2 DAY)`)