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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 (,) times in the result set. Notably, the Oracle platform provides a MINUS operator which is ...
The syntax of the SQL programming language is defined and maintained by ISO/IEC SC 32 as part of ISO/IEC 9075.This standard is not freely available. Despite the existence of the standard, SQL code is not completely portable among different database systems without adjustments.
The nested set model is a solution to that problem. An alternative solution is the expression of the hierarchy as a parent-child relation. Joe Celko called this the adjacency list model. If the hierarchy can have arbitrary depth, the adjacency list model does not allow the expression of operations such as comparing the contents of hierarchies ...
Some database systems allow the user to force the system to read the tables in a join in a particular order. This is used when the join optimizer chooses to read the tables in an inefficient order. For example, in MySQL the command STRAIGHT_JOIN reads the tables in exactly the order listed in the query. [16]
The detailed semantics of "the" ternary operator as well as its syntax differs significantly from language to language. A top level distinction from one language to another is whether the expressions permit side effects (as in most procedural languages) and whether the language provides short-circuit evaluation semantics, whereby only the selected expression is evaluated (most standard ...
It was developed by MySQL AB, and enables users to graphically administer MySQL databases and visually design database structures. Adminer – free MySQL front end capable of managing multiple databases, with many CSS skins available. It is a light-weight alternative to phpMyAdmin, distributed under the Apache license (or GPL v2) as a single ...
In logic, negation, also called the logical not or logical complement, is an operation that takes a proposition to another proposition "not ", written , , ′ [1] or ¯. [ citation needed ] It is interpreted intuitively as being true when P {\displaystyle P} is false, and false when P {\displaystyle P} is true.
Corner quotes, also called “Quine quotes”; for quasi-quotation, i.e. quoting specific context of unspecified (“variable”) expressions; [4] also used for denoting Gödel number; [5] for example “āGā” denotes the Gödel number of G. (Typographical note: although the quotes appears as a “pair” in unicode (231C and 231D), they ...