SQL: are multiple commands separated with ';' atomic or not?

Is it any information about commands separated with ';' inside one query - are they atomic or not? I'm interested in actual versions of popular databases: MySQL, MSSQL, SQLite etc? For example, if 100 clients will spam following query:

"insert into test ( name ) values ( '1' ); insert into test ( name ) values ( '2' )"

Will database contains items in sequence '1', '2', '1', '2' etc 开发者_Go百科or it is possible for each command divided by ';' from 100 clients to race each over, resulting in '1', '1', '2', '1', '2', '2', '2' etc ?

Wrap it in a transaction. Otherwise, no, there is in general no guarantee that your statements will be atomic.

Within the batch they will execute in sequential order, but that's not your problem. If 100 clients emit that SQL at the same time there is no guarantee that the 2 INSERTS will execute one after the other without another INSERT executing in-between.

I guess it's a theoretical question, but why would you need the sequence?

You can't rely on the sequence in the database anyway, so add some sort of timestamp-column to your table, and let your clients initialize a timestamp variable which they add to their records when inserting.