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  2. List of SQL reserved words - Wikipedia

    en.wikipedia.org/wiki/List_of_SQL_reserved_words

    Reserved words in SQL and related products In SQL:2023 [3] In IBM Db2 13 [4] In Mimer SQL 11.0 [5] In MySQL 8.0 [6] In Oracle Database 23c [7] In PostgreSQL 16 [1] In Microsoft SQL Server 2022 [2]

  3. 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 a single field (seconds, for instance) of a datetime or interval value.

  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. Database transaction - Wikipedia

    en.wikipedia.org/wiki/Database_transaction

    Transactions are available in most SQL database implementations, though with varying levels of robustness. For example, MySQL began supporting transactions from early version 3.23, but the InnoDB storage engine was not default before version 5.5.

  6. Optimistic concurrency control - Wikipedia

    en.wikipedia.org/wiki/Optimistic_concurrency_control

    Begin: Record a timestamp marking the transaction's beginning. Modify: Read database values, and tentatively write changes. Validate: Check whether other transactions have modified data that this transaction has used (read or written). This includes transactions that completed after this transaction's start time, and optionally, transactions ...

  7. Timestamp-based concurrency control - Wikipedia

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

    In this case, if the transaction's timestamp is after the object's read timestamp, the read timestamp is set to the transaction's timestamp. If a transaction wants to write to an object, but the transaction started before the object's read timestamp it means that something has had a look at the object, and we assume it took a copy of the object ...

  8. Timestamp - Wikipedia

    en.wikipedia.org/wiki/Timestamp

    The term "timestamp" derives from rubber stamps used in offices to stamp the current date, and sometimes time, in ink on paper documents, to record when the document was received. Common examples of this type of timestamp are a postmark on a letter or the "in" and "out" times on a time card.

  9. PHP syntax and semantics - Wikipedia

    en.wikipedia.org/wiki/PHP_syntax_and_semantics

    PHP has hundreds of base functions and thousands more from extensions. Prior to PHP version 5.3.0, functions are not first-class functions and can only be referenced by their name, whereas PHP 5.3.0 introduces closures. [35] User-defined functions can be created at any time and without being prototyped. [35]