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The skyline operator can be implemented directly in SQL using current SQL constructs, but this has been shown to be very slow in disk-based database systems. [1] Other algorithms have been proposed that make use of divide and conquer, indices, [1] MapReduce [3] and general-purpose computing on graphics cards. [4]
The following is a list of the highest-income ZCTAs in the United States. ZCTAs or ZIP Code Tabulation Areas are the census equivalent of ZIP codes used for statistical purposes. The reason why regular ZIP codes are not used is because they are defined by routes rather than geographic boundaries.
ZIP Code Tabulation Areas (ZCTAs) are statistical entities developed by the United States Census Bureau for tabulating summary statistics. These were introduced with the Census 2000 and continued with the 2010 Census and 5 year American Community Survey [ 1 ] datasets.
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
Map functions can be and often are defined in terms of a fold such as foldr, which means one can do a map-fold fusion: foldr f z . map g is equivalent to foldr (f . g) z . The implementation of map above on singly linked lists is not tail-recursive , so it may build up a lot of frames on the stack when called with a large list.
In computing, a materialized view is a database object that contains the results of a query.For example, it may be a local copy of data located remotely, or may be a subset of the rows and/or columns of a table or join result, or may be a summary using an aggregate function.
An alternative to implementing ORM is use of the native procedural languages provided with every major database. These can be called from the client using SQL statements. The Data Access Object (DAO) design pattern is used to abstract these statements and offer a lightweight object-oriented interface to the rest of the application. [5]
In addition to basic equality and inequality conditions, SQL allows for more complex conditional logic through constructs such as CASE, COALESCE, and NULLIF. The CASE expression, for example, enables SQL to perform conditional branching within queries, providing a mechanism to return different values based on evaluated conditions. This logic ...