Hello All !!! I've 2 tables in a Shopping Cart Servlet TransactionTable is having a one to many relation with OrderTable create table TransactionTable ( TransId Integer Not Null Auto_Increment Primary Key, OrderDate TimeStamp, Not Null , GrandTotal Double Not Null , FullName VarChar(40) Not Null , Address VarChar(100) Not Null , Pincode VarChar(10) Not Null , Phone VarChar(20) Not Null , Email VarChar(40) Not Null , city VarChar(20) Not Null , State VarChar(20) Not Null , Country VarChar(25) Not Null , Comments VarChar(240) ) ; create table OrderTable ( OrderId Integer Not Null Auto_Increment Primary Key, TransId Integer Not Null, TotalPrice Double Not Null , Code VarChar(20) Not Null , Quantity Integer Not Null ) ; My problem is how to enforce integrity between the updates ? That is there will be 1 or more enteries in the "OrderTable" againest every update in the "TransactionTable " table. The transId in Ordertable will be the same as the TransactionTable. So i'll have to read the transID by the function " Last_Insert_ID () "; But in the Event the database gets reset/ etc... etc... just after the Insert in the Transaction table it will leave the corresponding enteries orphaned in the OrdeTable . In that case what precautions should i take to avoid such scenarios????? How should i impose a lock on the tables ?? THe manual says To avoid using ROLLBACK, you can use the following strategy: 1.. Use LOCK TABLES ... to lock all the tables you want to access. 2.. Test conditions. 3.. Update if everything is okay. 4.. Use UNLOCK TABLES to release your locks. I didn't quite understasnd the meaning of Test Conditions Any help will be deeply appreciated Best Regards Sajan
