Hierarchical 2 network 3 relational and 4 object

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Unformatted text preview: ngle ordered file. Each of the constituent files must be in the same order, although the record layout of files need not be identical. The output file produced by the merging utility has the records in the same order as the input files, placing records from each in their correct relative order. Figure 16.6, illustrates the merging of two input files A and B to produce an output file C. Copying A file copying utility is used to produce an exact copy of a file, either from one unit of a storage device on to another similar unit (such as from one type reel to another or from one floppy disk to another), or from one storage medium to another (such as from tape to hard disk or from CD-ROM to hard disk). File copying utilities are often used for taking back-up copies of files. For example, a file may be copied from a hard disk to a tape or floppy for back-up purpose. File copying utilities are also known as peripheral interchange programs since they may be used to copy a file from one peripheral device on to another peripheral device. Printing A file printing utility is used to print a file on a printer to produce hard copy of its contents. Printing utilities often provide the facility to print file contents in different formats. They do often provide some selection and editing facilities to enable parts of files to be printed (such as specified number of records and only certain fields of records). Special printing facilities are often provided to print files that contain program instructions rather than data. Maintenance A file maintenance utility is used to selectively copy the data of one or more files into a new file, or to selectively update a file's contents. For example, facilities provided in a file maintenance utility may include the combining of data from more than one file into a single file, the deletion of records identified by record key or record count within a file, and the selection of specific fields of records to be copied from an existing file into a new file. DATABASE MANAGEMENT SYSTEM In the database-oriented approach of...
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This document was uploaded on 04/07/2014.

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