Search results
Results from the WOW.Com Content Network
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. This standard is not freely available. Despite the existence of the standard, SQL code is not completely portable among different database systems without adjustments.
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 ...
The Suppliers and Parts database is an example relational database that is referred to extensively in the literature [citation needed] and described in detail in C. J. Date's An Introduction to Database Systems, 8th ed. [1] It is a simple database comprising three tables: Supplier, Part and Shipment, and is often used as a minimal exemplar of the interrelationships found in a database.
The valid-time period is an interval based on event times, which are referred to as event datetime in data vault. [1] [2] Other names are application-time period [1] or real-world timeline. [1] SQL:2011 supports valid time through so-called application time-period tables.
The period is an interval based on load times (called load datetime in data vault [1] [2]), also called inscription timestamp. [1] Other names of the interval is assertion timeline [3]), state timeline [3]) or technical timeline. [3] SQL:2011 has support for transaction time through so-called system-versioned tables. [4] [5] [6] [7]
SQL-92 was the third revision of the SQL database query language. Unlike SQL-89, it was a major revision of the standard. Aside from a few minor incompatibilities, the SQL-89 standard is forward-compatible with SQL-92. The standard specification itself grew about five times compared to SQL-89.
It supports the CREATE SCHEMA syntax as a way to group DDL statements into a single unit creating all objects created as a part of the schema as a single owner. Informix supports a database mode called ANSI mode which supports creating objects with the same name but owned by different users.
The basic unit of a PL/SQL source program is the block, which groups together related declarations and statements. A PL/SQL block is defined by the keywords DECLARE, BEGIN, EXCEPTION, and END. These keywords divide the block into a declarative part, an executable part, and an exception-handling part.