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-- When converting a range of values where a default precision is required, -- that default is calculated for each value because the result sometimes -- depends on the precise input and output values. This function may cause -- the entire convert process to be repeated in order to ensure that the -- same default precision is used for each ...
computes the difference in seconds between two time_t values time: returns the current time of the system as a time_t value, number of seconds, (which is usually time since an epoch, typically the Unix epoch). The value of the epoch is operating system dependent; 1900 and 1970 are often used. See RFC 868. clock
Encoding free-form values: (e.g., mapping "Male" to "M") Deriving a new calculated value: (e.g., sale_amount = qty * unit_price) Sorting or ordering the data based on a list of columns to improve search performance; Joining data from multiple sources (e.g., lookup, merge) and deduplicating the data
In a database, a table is a collection of related data organized in table format; consisting of columns and rows.. In relational databases, and flat file databases, a table is a set of data elements (values) using a model of vertical columns (identifiable by name) and horizontal rows, the cell being the unit where a row and column intersect. [1]
In lieu of function pointers, functions in PHP can be referenced by a string containing their name. In this manner, normal PHP functions can be used, for example, as callbacks or within function tables. [225] User-defined functions may be created at any time without being prototyped.
The maximum value of a signed 32-bit integer is 2 31 − 1, and the minimum value is −2 31, making it impossible to represent dates before 13 December 1901 (at 20:45:52 UTC) or after 19 January 2038 (at 03:14:07 UTC). The early cutoff can have an impact on databases that are storing historical information; in some databases where 32-bit Unix ...
Comma-separated values is a data format that predates personal computers by more than a decade: the IBM Fortran (level H extended) compiler under OS/360 supported CSV in 1972. [14] List-directed ("free form") input/output was defined in FORTRAN 77, approved in 1978. List-directed input used commas or spaces for delimiters, so unquoted character ...
A delta can be defined in 2 ways, symmetric delta and directed delta.A symmetric delta can be expressed as (,) = (),where and represent two versions.. A directed delta, also called a change, is a sequence of (elementary) change operations which, when applied to one version , yields another version (note the correspondence to transaction logs in databases).