Oracle SQL*Plus: The Definitive Guide

Reloading the Data

Now that you know how to extract data from Oracle, you need to know how to load it back in again. This is easy if you have generated a file of SQL commands — you simply execute that file from within SQL*Plus. Loading data is a little tougher, however, if you have a file of comma-delimited or fixed-width data.

In order to load data into Oracle from a flat file, you need to use a tool called SQL*Loader. SQL*Loader is a generic utility provided by Oracle for the express purpose of loading data into the database from a file. An entire book could be written about SQL*Loader, so it’s not possible to cover it exhaustively in the remainder of this chapter. What I can do is show you how to use SQL*Loader to reload the employee table from either a comma-delimited or fixed-width text file — the same files you learned how to create in this chapter. That should be enough to get you started.

Executing DDL and DML

If you extract data by using SQL*Plus to create a file of INSERT commands, loading the data somewhere else is as simple as creating the necessary table and executing the file. If you created a file of DDL commands, such as the CREATE PUBLIC SYNONYM commands shown earlier, you only need to execute that file.

Tip

You may want to turn ECHO on, and spool the output of any files that you execute, so you can go back and check for errors later.

Running SQL*Loader

As I mentioned, SQL*Loader is Oracle’s data loading utility, a general-purpose utility that can be configured ...