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The SQL function EXTRACT can be used for extracting a single field (seconds, for instance) of a datetime or interval value. The current system date / time of the database server can be called by using functions like CURRENT_DATE, CURRENT_TIMESTAMP, LOCALTIME, or LOCALTIMESTAMP.
The effect is similar to searching for a specific term in a book that has no index, beginning at page one each time, instead of jumping to a list of specific pages identified in an index. The typical situation that will make a SQL query non-sargable is to include in the WHERE clause a function operating on a column value. The WHERE clause is ...
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 ...
Date variables can contain date and time. The time may be left out, but there is no way to define a variable that only contains the time. There is no DATETIME type. And there is a TIME type. But there is no TIMESTAMP type that can contain fine-grained timestamp up to millisecond or nanosecond.
Time zone abbreviations for both Standard Time and Daylight Saving Time are shown exactly as they appear in the database. See strftime and its "%Z" field. Some of zone records use 3 or 4 letter abbreviations that are tied to physical time zones, others use numeric UTC offsets.
The time when a transaction is valid can be called the transaction time-period. It is a technical timeline controlled by a integration layer (for example a data warehouse ). [ 1 ] More formally, it is the point-in-time during which a fact stored in the database is considered to be true.
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.
In very early versions of the SQL standard the return code was called SQLCODE and used a different coding schema. The following table lists the standard-conforming values - based on SQL:2011 . [ 1 ] The table's last column shows the part of the standard that defines the row.