Relational Database Index Design and the Optimizers (Wiley, July 2005) is an excellent book on how indexes work in general in a relational database. The authors focused on principles and not any particular database vendor. The book focuses on two things; first, the database optimizer of the relational system has to decide how to find …
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OVERLAPS predicate is a useful feature, which is not available in most SQL implementations that can help to determine whether the two periods overlap each other. If two periods overlap then the predicate evaluates to TRUE otherwise FALSE. Let us create a test table with three rows – one with overlapping dates, second with non-overlapping …
Man: man command formats and displays the on-line manual pages. If you specify section, man only looks in that section of the manual. name is normally the name of the manual page, which is typically the name of a command, function, or file. Whatis: whatis command searches a set of database files containing short descriptions …