Understanding SQL Loader#
SQL Loader is a utility created by Oracle and installed onto the database server during the installation of the software, as well as a large number of other programs. SQL Loader loads data in a variety of formats, performs filtering (selectively loading records based upon the data values), and loads multiple tables simultaneously. During execution, SQL Loader produces a detailed log file with statistics about the load. It may also produce a bad file (containing records rejected because of incorrect data) and a discard file (containing records that did not meet the specified selection criteria).SQL Loader can:
- load data from multiple data files of different file types
- handle fixed-format, delimited-format, and variable-length records
- manipulate data fields with SQL functions before inserting the data into database columns
- support a wide range of data types, including DATE, BINARY, PACKED DECIMAL, and ZONED DECIMAL
- load multiple tables during the same run, loading selected rows into each table
- combine multiple physical records into a single logical record
- treat a single physical record as multiple logical records
- generate unique, sequential key values in specified columns
- use your operating system's file or record management system to access data files
- load data from disk or tape
- provide thorough error reporting capabilities, so you can easily adjust and load all records
Data to be loaded into the Oracle database must exist in files on disk. These data files require mapping (translation to Oracle format) to be loaded by SQL Loader. You specify how SQL Loader interprets the data via data definitions contained in control files. The control file also is the repository for certain file management information.
