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Oracle SQL Plus The Definitive Guide- P19

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Oracle SQL Plus The Definitive Guide- P19:Every day, computer professionals the world over wake up, travel to the office, sit down in front of a computer, and begin another day working with that database called Oracle. Programmers write queries and stored procedures. Database administrators monitor performance, make database changes, and perform other maintenance tasks. Operations people may need to back up or recover a database. | previous page page_156 next page Page 156 Types of Output Files Generally speaking there are four types of output files you can produce when extracting data with SQL Plus Delimited columns Fixed-width columns DML Data Manipulation Language DDL Data Definition Language There may be variations on these typesdelimited files for example could be either tab-delimited or comma-delimited and you may be able to dream up some novel format but generally speaking these are the most useful. Delimited Files Delimited files use a special text character to separate each data value in a record. Typically the delimiter is either a tab or a comma but any character may be used. Here s an example of a comma-delimited file containing employee information ID rate hire date and name 1 135 15-Nov-1961 Jonathan Gennick 2 95 10-Jan-1991 Bohdan Khmelnytsky 3 200 17-Jul-1984 Ivan Mazepa This example illustrates a very commonly used format called the CSV Comma Separated Values format. CSV-formatted files use commas to delimit the values and they enclose text fields within quotes. The CSV format is recognized by most spreadsheets and desktop databases and is the format for the examples in this chapter. Fixed-Width Files A fixed-width file contains data in columns where each column is a certain width and all values in that column are the same width. Here s an example of the same employee data shown earlier but formatted into fixed-width columns 00113515-Nov-1961Jonathan Gennick 00209510-Jan-1991Bohdan Khmelnytsky 00320017-Jul-1984Ivan Mazepa In the above example the columns abut each other with no space in between. If you aren t trying to match an existing file layout you may prefer to allow at least one space between columns to aid readability. page_156 previous page next page previous page page_157 next page Page 157 DML Files. A DML file contains Data Manipulation Language statements such as INSERT DELETE UPDATE and SELECT. This type of file can be used as a quick and dirty way of extracting