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It is a collection of character data in a database management system, usually stored in a separate location that is referenced in the table itself. Oracle and IBM Db2 provide a construct explicitly named CLOB, [1] [2] and the majority of other database systems support some form of the concept, often labeled as text, memo or long character fields.
In object-oriented programming, classes can contain attributes and methods. An attribute in a relational database can be represented as a column or field.. In computing, an attribute is a specification that defines a property of an object, element, or file.
The OFFSET clause specifies the number of rows to skip before starting to return data. The FETCH FIRST clause specifies the number of rows to return. Some SQL databases instead have non-standard alternatives, e.g. LIMIT, TOP or ROWNUM. The clauses of a query have a particular order of execution, [5] which is denoted by the number on the right ...
A WHERE clause in SQL specifies that a SQL Data Manipulation Language (DML) statement should only affect rows that meet specified criteria. The criteria are expressed in the form of predicates. WHERE clauses are not mandatory clauses of SQL DML statements, but can be used to limit the number of rows affected by a SQL DML statement or returned ...
By contrast, a character entity reference refers to a sequence of one or more characters by the name of an entity which has the desired characters as its replacement text. The entity must either be predefined (built into the markup language), or otherwise explicitly declared in a Document Type Definition (DTD) (see [a]). The format is the same ...
The characters in the brackets may be a list ([abc]) or a range ([a-c]) or denote a character class (like [[:space:]] where the inner brackets are part of the classname). POSIX does not mandate multi-range ( [a-c0-3] ) support, which derive originally from regular expressions .
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 ...