LOCK TABLES usage

[Magnus Bjorkman]

I have a situation where I’m not sure how to handle locking etc.

Setup:
1 Table (TAB1) holding an ID.
3 Tables (TABLE_A, _B, _C) where the ID is incremented and used for insert.

Logic (at various places depending on what table to insert in):
getID = SELECT ID+1 FROM TAB1
Update TAB1 SET ID=ID+1+[NumOfRowsToInsert]
Autocommit false
While MoreRowsToUpdate {
Insert into TABLE_A …
(…, ID, …) Values (…, getID, …)

getID++
}
If OK
commit
else
rollback
AutoCommit=true

Question:
How can I make sure that the getID and UPDATE TAB1 is in sync (i.e. no other user can do an update in between) ?