在实际的mysql系统中处理DELETE的最佳方法

Question

I am working on a web project using Spring Boot + mySql

and I am thinking about how to delete data from the database.

I know the DELETE * FROM table statement, but I have questions,

1. Is there any way to keep the history or operation logs using DELETE?
2. If I delete the data using DELETE, then I add a new one, the new data will insert into the place that was deleted, so the id is mis-ordered right?

My friend suggest me to add a BOOL column to each table, which is delete flag, in order to control the delete process, is it a nice way to do so?

Sorry, I am newbie to server development, so I want to make sure each step is robust. Thank you in advance.

Answer 1

Is there any way to keep the history or operation logs using DELETE?

You can do it or by tracing these operation in a log file or by putting a trigger on the DB so that each delete will be traced (for example a new record in a new table will be created). Personally I'd prefer to use the log file so yuo can configure your logging framework in several types (or by saving on DB, or in a log file or by using syslog etc...)

If I delete the data using DELETE, then I add a new one, the new data will insert into the place that was deleted, so the id is mis-ordered right?

No; the new record will have its own ID

My friend suggest me to add a BOOL column to each table, which is delete flag, in order to control the delete process, is it a nice way to do so?

In this case you are doing not a real delete but a logical delete; the record is not phisically deleted from the DB but it is marked as deleted. This impacts on all other queries (for example you have to choice all records with delete flag false because the ones with delete flag true are "deleted") This can be useful to store all changes but you have also to think about tables dimension... records will always be added and never really deleted...

Personally I'd move by using the log file and deleting the record

I hope this can help

Angelo

Answer 2

Q1. Is there any way to keep the history or operation logs using DELETE? A1. You are working on the server side so while deleting you can generate logs in your code using any logger of your choices like Log4j or SLF4j.

Q2. If I delete the data using DELETE, then I add a new one, the new data will insert into the place that was deleted, so the id is misordered right? A2. No MySQL will not use the same key.

What your friend suggest is the soft delete, means the data still available in the system. But it makes your table bigger everytime. Actually, you can use multiple approaches here its totally depend on your requirements like you need that data you want to delete or not.