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  2. SQL syntax - Wikipedia

    en.wikipedia.org/wiki/SQL_syntax

    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. The SQL function EXTRACT can be used for extracting

  3. Comparison of relational database management systems - Wikipedia

    en.wikipedia.org/wiki/Comparison_of_relational...

    The SQL specification defines what an "SQL schema" is; however, databases implement it differently. To compound this confusion the functionality can overlap with that of a parent database. An SQL schema is simply a namespace within a database; things within this namespace are addressed using the member operator dot ".". This seems to be a ...

  4. 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 ...

  5. Timestamp-based concurrency control - Wikipedia

    en.wikipedia.org/wiki/Timestamp-based...

    These timestamps ensure that transactions affect each object in the same sequence of their respective timestamps. Thus, given two operations that affect the same object from different transactions, the operation of the transaction with the earlier timestamp must execute before the operation of the transaction with the later timestamp.

  6. Temporal database - Wikipedia

    en.wikipedia.org/wiki/Temporal_database

    A substantive difference between the TSQL2 proposal and what was adopted in SQL:2011 is that there are no hidden columns in the SQL:2011 treatment, nor does it have a new data type for intervals; instead two columns with datestamps (DS) or date-timestamps (DTS) can be bound together using a PERIOD FOR declaration. Another difference is ...

  7. Time formatting and storage bugs - Wikipedia

    en.wikipedia.org/wiki/Time_formatting_and...

    The 64-bit timestamps used by NTP consist of a 32-bit part for seconds and a 32-bit part for fractional second, giving NTP a time scale that rolls over every 2 32 seconds (136 years) and a theoretical resolution of 2 −32 second (233 picoseconds). NTP uses an epoch of 1 January 1900.

  8. ISO 8601 - Wikipedia

    en.wikipedia.org/wiki/ISO_8601

    ISO 8601 is an international standard covering the worldwide exchange and communication of date and time-related data.It is maintained by the International Organization for Standardization (ISO) and was first published in 1988, with updates in 1991, 2000, 2004, and 2019, and an amendment in 2022. [1]

  9. PL/SQL - Wikipedia

    en.wikipedia.org/wiki/PL/SQL

    PL/SQL provides the functionality of other procedural programming languages, such as decision making, iteration etc. A PL/SQL program unit is one of the following: PL/SQL anonymous block, procedure, function, package specification, package body, trigger, type specification, type body, library. Program units are the PL/SQL source code that is ...