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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; Definition of application time period tables (elsewhere called valid time tables), using the PERIOD FOR annotation
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.
A valid time period may be in the past, span the current time, or occur in the future. For the example above, to record valid time, the person table has two fields added, valid_from and valid_to. These specify the period when a person's address is valid in the real world. On 1975-04-04, John's father registered his son's birth.
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.
This can result in the accumulation of a large number of records in a fact table over time. Fact tables are defined as one of three types: Transaction fact tables record facts about a specific event (e.g., sales events) Snapshot fact tables record facts at a given point in time (e.g., account details at month end) Accumulating snapshot tables ...
In SQL:1999 a recursive (CTE) query may appear anywhere a query is allowed. It's possible, for example, to name the result using CREATE [ RECURSIVE ] VIEW . [ 16 ] Using a CTE inside an INSERT INTO , one can populate a table with data generated from a recursive query; random data generation is possible using this technique without using any ...
In the first overtime period, a team has the option of kicking an extra point or attempting a two-point conversion. In the second overtime, that choice is gone, with both teams having to go for two.
Major DBMSs, including SQLite, [5] MySQL, [6] Oracle, [7] IBM Db2, [8] Microsoft SQL Server [9] and PostgreSQL [10] support prepared statements. Prepared statements are normally executed through a non-SQL binary protocol for efficiency and protection from SQL injection, but with some DBMSs such as MySQL prepared statements are also available using a SQL syntax for debugging purposes.