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  2. Set operations (SQL) - Wikipedia

    en.wikipedia.org/wiki/Set_operations_(SQL)

    For purposes of row elimination and duplicate removal, the EXCEPT operator does not distinguish between NULLs. The EXCEPT ALL operator does not remove duplicates, but if a row appears X times in the first query and Y times in the second, it will appear max ( X − Y , 0 ) {\displaystyle \max(X-Y,0)} times in the result set.

  3. Null (SQL) - Wikipedia

    en.wikipedia.org/wiki/Null_(SQL)

    Although Don Chamberlin recognized nulls (alongside duplicate rows) as one of the most controversial features of SQL, he defended the design of Nulls in SQL invoking the pragmatic arguments that it was the least expensive form of system support for missing information, saving the programmer from many duplicative application-level checks (see ...

  4. SQL - Wikipedia

    en.wikipedia.org/wiki/SQL

    Another popular criticism is that it allows duplicate rows, making integration with languages such as Python, whose data types might make accurately representing the data difficult, [12] in terms of parsing and by the absence of modularity. This is usually avoided by declaring a primary key, or a unique constraint, with one or more columns that ...

  5. Checkmk - Wikipedia

    en.wikipedia.org/wiki/Checkmk

    Checkmk is a software system developed in Python and C++ for IT Infrastructure monitoring. It is used for the monitoring of servers, applications, networks, cloud infrastructures (public, private, hybrid), containers, storage, databases and environment sensors.

  6. Error correction code - Wikipedia

    en.wikipedia.org/wiki/Error_correction_code

    Turbo coding is an iterated soft-decoding scheme that combines two or more relatively simple convolutional codes and an interleaver to produce a block code that can perform to within a fraction of a decibel of the Shannon limit.

  7. Table (database) - Wikipedia

    en.wikipedia.org/wiki/Table_(database)

    In a database, a table is a collection of related data organized in table format; consisting of columns and rows.. In relational databases, and flat file databases, a table is a set of data elements (values) using a model of vertical columns (identifiable by name) and horizontal rows, the cell being the unit where a row and column intersect. [1]

  8. Exception handling (programming) - Wikipedia

    en.wikipedia.org/wiki/Exception_handling...

    Excluding minor syntactic differences, there are only a couple of exception handling styles in use. In the most popular style, an exception is initiated by a special statement (throw or raise) with an exception object (e.g. with Java or Object Pascal) or a value of a special extendable enumerated type (e.g. with Ada or SML).

  9. Control flow - Wikipedia

    en.wikipedia.org/wiki/Control_flow

    Both Python's for and while loops support such an else clause, which is executed only if early exit of the loop has not occurred. Some languages support breaking out of nested loops; in theory circles, these are called multi-level breaks. One common use example is searching a multi-dimensional table.