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In many programming languages, string concatenation is a binary infix operator, and in some it is written without an operator. This is implemented in different ways: Overloading the plus sign + Example from C#: "Hello, " + "World" has the value "Hello, World". Dedicated operator, such as . in PHP, & in Visual Basic [1] and || in SQL.
The Skip and SkipWhile operators are complements of Take and TakeWhile - they skip the first n objects from a collection, or those objects that match a predicate (for the case of SkipWhile). OfType The OfType operator is used to select the elements of a certain type. Concat The Concat operator concatenates two collections. OrderBy / ThenBy
Set operations in SQL is a type of operations which allow the results of multiple queries to be combined into a single result set. [1] Set operators in SQL include UNION, INTERSECT, and EXCEPT, which mathematically correspond to the concepts of union, intersection and set difference.
The relational algebra uses set union, set difference, and Cartesian product from set theory, and adds additional constraints to these operators to create new ones.. For set union and set difference, the two relations involved must be union-compatible—that is, the two relations must have the same set of attributes.
SQL includes operators and functions for calculating values on stored values. SQL allows the use of expressions in the select list to project data, as in the following example, which returns a list of books that cost more than 100.00 with an additional sales_tax column containing a sales tax figure calculated at 6% of the price.
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 ...
However, removing the feature breaks backwards compatibility, and replacing it with a concatenation operator introduces issues of precedence – string literal concatenation occurs during lexing, prior to operator evaluation, but concatenation via an explicit operator occurs at the same time as other operators, hence precedence is an issue ...
The following operators have the given precedence from tightest binding to loosest binding: Strings, names formation; Comment; Value range; Repetition; Grouping, optional; Concatenation; Alternative; Use of the alternative operator with concatenation may be confusing, and it is recommended that grouping be used to make explicit concatenation ...