![]() I want to be able to just send a series of SQL commands in a transaction as a one block of text and have SQLite tell me either that it succeeded so committed, or that it failed so everything has been rolled back. It works, but it requires a whole extra level of interaction, whereas I want to SQL to take care of it itself, without needing to dissect and branch the SQL in application code. Rather than generating the beginning and end of the transaction from a different part of the application code to each statement inside? Begin transaction, then start executing statements from a list if any of them fail, stop executing further statements and roll back, otherwise commit at the end. ![]() Is there a way to do this in pure SQL, without my application code having to check for errors along the way and then interrogate the SQL to look for a "commit" type line and replace it? This seems pretty error prone and convoluted. So, it seems I have to, in my application code, step through each command in the SQL transaction, note any error, then when it gets to a "commit" command, replace it instead with a "rollback". However, depending on the statement being evaluated and the point at which the error occurs, it might be necessary for SQLite to rollback and cancel the entire transaction. SQLITE_INTERRUPT: processing interrupted by application requestįor all of these errors, SQLite attempts to undo just the one statement it was working on and leave changes from prior statements within the same transaction intact and continue with the transaction.SQLITE_BUSY: database in use by another process.Let's start another transaction and delete records from the table having age = 25 and finally we use COMMIT command to commit all the changes. Now, if you check COMPANY table, it still has the following records − Sqlite> DELETE FROM COMPANY WHERE AGE = 25 Then, use ROLLBACK command to undo all the changes. Now, let's start a transaction and delete records from the table having age = 25. ROLLBACK command can only be used to undo transactions since the last COMMIT or ROLLBACK command was issued.įollowing is the syntax for ROLLBACK command.Ĭonsider COMPANY table with the following records. ROLLBACK command is the transactional command used to undo transactions that have not already been saved to the database. Following is the simple syntax to start a transaction.ĬOMMIT command is the transactional command used to save changes invoked by a transaction to the database.ĬOMMIT command saves all transactions to the database since the last COMMIT or ROLLBACK command.įollowing is the syntax for COMMIT command. However, a transaction will also ROLLBACK if the database is closed or if an error occurs. Such transactions usually persist until the next COMMIT or ROLLBACK command is encountered. Transactions can be started using BEGIN TRANSACTION or simply BEGIN command. They cannot be used while creating tables or dropping them because these operations are automatically committed in the database. Transactional control commands are only used with DML commands INSERT, UPDATE, and DELETE. Isolation − Enables transactions to operate independently of and transparent to each other.ĭurability − Ensures that the result or effect of a committed transaction persists in case of a system failure.įollowing are the following commands used to control transactions:īEGIN TRANSACTION − To start a transaction.ĬOMMIT − To save the changes, alternatively you can use END TRANSACTION command. Transactions have the following four standard properties, usually referred to by the acronym ACID.Ītomicity − Ensures that all operations within the work unit are completed successfully otherwise, the transaction is aborted at the point of failure and previous operations are rolled back to their former state.Ĭonsistency − Ensures that the database properly changes states upon a successfully committed transaction. Practically, you will club many SQLite queries into a group and you will execute all of them together as part of a transaction. It is important to control transactions to ensure data integrity and to handle database errors. For example, if you are creating, updating, or deleting a record from the table, then you are performing transaction on the table. Transactions are units or sequences of work accomplished in a logical order, whether in a manual fashion by a user or automatically by some sort of a database program.Ī transaction is the propagation of one or more changes to the database. A transaction is a unit of work that is performed against a database.
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