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These mistakes are usually the result of confusion between Null and either 0 (zero) or an empty string (a string value with a length of zero, represented in SQL as ''). Null is defined by the SQL standard as different from both an empty string and the numerical value 0, however. While Null indicates the absence of any value, the empty string ...
Without an ORDER BY clause, the order of rows returned by an SQL query is undefined. The DISTINCT keyword [5] eliminates duplicate data. [6] The following example of a SELECT query returns a list of expensive books. The query retrieves all rows from the Book table in which the price column contains a value greater
Stata utilizes integer storage types which occupy only one or two bytes rather than four, and single-precision (4 bytes) rather than double-precision (8 bytes) is the default for floating-point numbers. Stata's proprietary output language is known as SMCL, which stands for Stata Markup and Control Language and is pronounced "smickle". [10]
Object REXX is a high-level, general-purpose, interpreted, object-oriented (class-based) programming language.Today it is generally referred to as ooRexx (short for “Open Object Rexx”), which is the maintained and direct open-source successor to Object REXX.
(empty set) ∅ denoting the set ∅. (empty string) ε denoting the set containing only the "empty" string, which has no characters at all. (literal character) a in Σ denoting the set containing only the character a. Given regular expressions R and S, the following operations over them are defined to produce regular expressions:
Replace all consonants (include the first letter) with digits as in [2.] above. Replace all adjacent same digits with one digit, and then remove all the zero (0) digits; If the saved letter's digit is the same as the resulting first digit, remove the digit (keep the letter). Append 3 zeros if result contains less than 3 digits.
The empty string has several properties: |ε| = 0. Its string length is zero. ε ⋅ s = s ⋅ ε = s. The empty string is the identity element of the concatenation operation. The set of all strings forms a free monoid with respect to ⋅ and ε. ε R = ε. Reversal of the empty string produces the empty string, so the empty string is a palindrome.
A node may be left blank, a literal and/or be identified by a URI. An arc may also be identified by a URI. A literal for a node may be of two types: plain (untyped) and typed. A plain literal has a lexical form and optionally a language tag. A typed literal is made up of a string with a URI that identifies a particular datatype.