How to solve the problem of duplicate mysql database IDs that cannot be deleted _ MySQL

Solution for duplicate mysql database IDs that cannot be deleted bitsCN.com

How can I delete a duplicate mysql database id?

Since I haven't engaged in databases for a long time, I forgot a lot about SQL statements.

Recently, this is only because Mysql is used in the backend of the server to store data,

To make online time statistics, the server must record the online status of users in some time periods.

In fact, implementation is not very difficult, but when there are multiple lines, it may involve writing data to the database from multiple servers. at this time, if

It is very difficult to determine the id through the upper layer. Therefore, the id should be updated automatically.

For example, if Column a is defined as unique and the value is 1, the following statements have the same effect, that is, once the entry and exit records contain a = 1, directly update c = c + 1 without executing c = 3.

1 insert into table (a, B, c) values (1, 2, 3) on duplicate key update c = c + 1;

1 update table set c = c + 1 where a = 1;

It is also worth mentioning that this statement is in mysql, but not in standard SQL statements.

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