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A view is defined by giving a name to such an expression, such that the name can subsequently be used as a variable name. (Note that the expression must then mention at least one base relation variable.) By using a Data Definition Language (DDL), it is able to define base relation variables. In SQL, CREATE TABLE syntax is used to define base ...
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 ...
A table in a SQL database schema corresponds to a predicate variable; the contents of a table to a relation; key constraints, other constraints, and SQL queries correspond to predicates. However, SQL databases deviate from the relational model in many details, and Codd fiercely argued against deviations that compromise the original principles. [3]
[[Category:Date-computing templates based on current time]] to the <includeonly> section at the bottom of that page. Otherwise, add <noinclude>[[Category:Date-computing templates based on current time]]</noinclude> to the end of the template code, making sure it starts on the same line as the code's last character.
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.
In the example above, the first datum is 66. This number was obtained by finding all records where both Region was East and Ship Date was 2005-01-31, and adding the Units of that collection of records (i.e., cells E2 to E7) together to get a final result. Pivot tables are not created automatically.
The listagg function, as defined in the SQL:2016 standard [2] aggregates data from multiple rows into a single concatenated string. In the entity relationship diagram, aggregation is represented as seen in Figure 1 with a rectangle around the relationship and its entities to indicate that it is being treated as an aggregate entity. [3]
To a user, SAP IQ looks just like any relational DBMS with a SQL-based language layer accessible via ODBC/JDBC drivers. However, inside, Sybase IQ is a column-oriented DBMS , which stores data tables as sections of columns of data rather than as rows of data like most transactional databases.