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SQL-92 was the third revision of the SQL database query language. Unlike SQL-89, it was a major revision of the standard. Aside from a few minor incompatibilities, the SQL-89 standard is forward-compatible with SQL-92. The standard specification itself grew about five times compared to SQL-89.
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Query rewriting is a typically automatic transformation that takes a set of database tables, views, and/or queries, usually indices, often gathered data and query statistics, and other metadata, and yields a set of different queries, which produce the same results but execute with better performance (for example, faster, or with lower memory use). [1]
Unix time [a] is a date and time representation widely used in computing. It measures time by the number of non-leap seconds that have elapsed since 00:00:00 UTC on 1 January 1970, the Unix epoch. For example, at midnight on 1 January 2010, Unix time was 1262304000. Unix time originated as the system time of Unix operating systems.
millisecond: ms One thousandth of one second 1 ms: The time for a neuron in the human brain to fire one impulse and return to rest [13] 4–8 ms: The typical seek time for a computer hard disk: 10 −2: centisecond cs One hundredth of one second 1.6667 cs: The period of a frame at a frame rate of 60 Hz.
A query includes a list of columns to include in the final result, normally immediately following the SELECT keyword. An asterisk ("*") can be used to specify that the query should return all columns of all the queried tables. SELECT is the most complex statement in SQL, with optional keywords and clauses that include:
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]
The C date and time functions are a group of functions in the standard library of the C programming language implementing date and time manipulation operations. [1] They provide support for time acquisition, conversion between date formats, and formatted output to strings.