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  2. SQL syntax - Wikipedia

    en.wikipedia.org/wiki/SQL_syntax

    TIME: for time values (e.g. 15:51:36). TIME WITH TIME ZONE: the same as TIME, but including details about the time zone in question. TIMESTAMP: This is a DATE and a TIME put together in one variable (e.g. 2011-05-03 15:51:36.123456). TIMESTAMP WITH TIME ZONE: the same as TIMESTAMP, but including details about the time zone in question.

  3. PL/SQL - Wikipedia

    en.wikipedia.org/wiki/PL/SQL

    PL/SQL refers to a class as an "Abstract Data Type" (ADT) or "User Defined Type" (UDT), and defines it as an Oracle SQL data-type as opposed to a PL/SQL user-defined type, allowing its use in both the Oracle SQL Engine and the Oracle PL/SQL engine. The constructor and methods of an Abstract Data Type are written in PL/SQL.

  4. Conjunctive query - Wikipedia

    en.wikipedia.org/wiki/Conjunctive_Query

    Conjunctive queries without distinguished variables are called boolean conjunctive queries.Conjunctive queries where all variables are distinguished (and no variables are bound) are called equi-join queries, [1] because they are the equivalent, in the relational calculus, of the equi-join queries in the relational algebra (when selecting all columns of the result).

  5. Query language - Wikipedia

    en.wikipedia.org/wiki/Query_language

    Broadly, query languages can be classified according to whether they are database query languages or information retrieval query languages. The difference is that a database query language attempts to give factual answers to factual questions, while an information retrieval query language attempts to find documents containing information that is relevant to an area of inquiry.

  6. Optimistic concurrency control - Wikipedia

    en.wikipedia.org/wiki/Optimistic_concurrency_control

    This includes transactions that completed after this transaction's start time, and optionally, transactions that are still active at validation time. Commit/Rollback: If there is no conflict, make all changes take effect. If there is a conflict, resolve it, typically by aborting the transaction, although other resolution schemes are possible.

  7. SQL - Wikipedia

    en.wikipedia.org/wiki/SQL

    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 ...

  8. SQL:2011 - Wikipedia

    en.wikipedia.org/wiki/SQL:2011

    Time period definitions use two standard table columns as the start and end of a named time period, with closed set-open set semantics. This provides compatibility with existing data models, application code, and tools

  9. User-defined function - Wikipedia

    en.wikipedia.org/wiki/User-defined_function

    2. On Microsoft SQL Server 2005 the result of the same code execution is the opposite: view is executed faster than the "function-wrapper". User-defined functions are subroutines made of one or more Transact-SQL statements that can be used to encapsulate code for reuse. It takes zero or more arguments and evaluates a return value.