In Oracle, the equivalent for @@error in SQL Server is the SQLCODE function. SQLCODE returns the numeric error code for the last executed SQL statement. It is often used in conjunction with the SQLERRM function, which returns the error message associated with the error code. Together, SQLCODE and SQLERRM can be used to handle and display errors in Oracle PL/SQL code.
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How to rollback transactions in case of errors in Oracle?
To rollback a transaction in Oracle in case of errors, you can use the ROLLBACK statement. Here is how you can rollback a transaction when an error occurs:
- Use a BEGIN...END block to start a transaction and catch any errors:
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BEGIN -- Start transaction INSERT INTO table_name (column1, column2) VALUES (value1, value2); -- Commit the transaction COMMIT; EXCEPTION -- Rollback the transaction if an error occurs WHEN OTHERS THEN ROLLBACK; END; |
- Alternatively, you can use the SAVEPOINT statement to create a savepoint in the transaction and rollback to that savepoint if an error occurs. Here is an example:
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SAVEPOINT start_transaction; -- Start transaction INSERT INTO table_name (column1, column2) VALUES (value1, value2); -- If an error occurs, rollback to the savepoint ROLLBACK TO start_transaction; |
Remember to always rollback a transaction in case of errors to ensure data consistency and integrity.
How to raise custom errors in Oracle?
In Oracle PL/SQL, you can raise custom errors using the RAISE_APPLICATION_ERROR procedure. This procedure allows you to raise an error with a user-defined error code and message.
Here is an example of how to use the RAISE_APPLICATION_ERROR procedure to raise a custom error:
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DECLARE custom_error EXCEPTION; BEGIN RAISE custom_error; END; / |
In this example, we declare a custom error named custom_error and then use the RAISE statement to raise the error. You can also provide an error number and error message as arguments to the RAISE statement, like this:
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DECLARE custom_error EXCEPTION; BEGIN RAISE_APPLICATION_ERROR(-20001, 'This is a custom error message.'); END; / |
In this example, we are raising a custom error with an error code of -20001 and a custom error message.
You can then handle these custom errors in your PL/SQL blocks using exception handling techniques.
What is the difference between RAISE_APPLICATION_ERROR and @@error in Oracle?
RAISE_APPLICATION_ERROR is a built-in procedure in Oracle PL/SQL that allows you to raise a custom exception with a user-defined error code and message. This can be used to handle errors and communicate specific error messages to the user or application.
On the other hand, @@error is a system function in SQL Server that allows you to retrieve the error number generated by the last executed statement. It is used to check for errors in T-SQL code and take appropriate actions based on the error number.
In summary, RAISE_APPLICATION_ERROR is used to raise custom exceptions with specific error codes and messages in PL/SQL, while @@error is used to retrieve error numbers in SQL Server.
