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Set-Membership constraints: The values for a column come from a set of discrete values or codes. For example, a person's sex may be Female, Male or Non-Binary. Foreign-key constraints: This is the more general case of set membership. The set of values in a column is defined in a column of another table that contains unique values.
In object-oriented computer programming, a null object is an object with no referenced value or with defined neutral (null) behavior.The null object design pattern, which describes the uses of such objects and their behavior (or lack thereof), was first published as "Void Value" [1] and later in the Pattern Languages of Program Design book series as "Null Object".
In computing, a null pointer or null reference is a value saved for indicating that the pointer or reference does not refer to a valid object. Programs routinely use null pointers to represent conditions such as the end of a list of unknown length or the failure to perform some action; this use of null pointers can be compared to nullable types ...
Pandas is built around data structures called Series and DataFrames. Data for these collections can be imported from various file formats such as comma-separated values, JSON, Parquet, SQL database tables or queries, and Microsoft Excel. [8] A Series is a 1-dimensional data structure built on top of NumPy's array.
English: PDF version of the Java Persistence Wikibook. This file was created with MediaWiki to LaTeX . The LaTeX source code is attached to the PDF file (see imprint).
A Doclet is written in Java and uses the Doclet API, The StandardDoclet included with Javadoc generates API documentation as frame-based HTML files. Other Doclets are available on the web [citation needed], often for free. These can be used to: Create other types of documentation (non-API) Output to a format other than HTML; such as PDF
Linearized PDF files (also called "optimized" or "web optimized" PDF files) are constructed in a manner that enables them to be read in a Web browser plugin without waiting for the entire file to download, since all objects required for the first page to display are optimally organized at the start of the file. [26]
Gary Kessler's list of file signatures; Online File Signature Database for Forensic Practitioners, a private compilation free to Law Enforcement; Man page for compress, uncompress, and zcat on SCO Open Server; Public Database of File Signatures [dead link ] Complete list of magic numbers with sample files