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All types, even value types in their boxed form, implicitly inherit from the System. Object class, the ultimate base class of all objects. This class contains the most common methods shared by all objects. Some of these are virtual and can be overridden. Classes inherit System. Object either directly or indirectly through another base class ...
By default, a Pandas index is a series of integers ascending from 0, similar to the indices of Python arrays. However, indices can use any NumPy data type, including floating point, timestamps, or strings. [4]: 112 Pandas' syntax for mapping index values to relevant data is the same syntax Python uses to map dictionary keys to values.
For referential integrity to hold in a relational database, any column in a base table that is declared a foreign key can only contain either null values or values from a parent table's primary key or a candidate key. [2] In other words, when a foreign key value is used it must reference a valid, existing primary key in the parent table.
Boxing is the operation of converting a value-type object into a value of a corresponding reference type. [108] Boxing in C# is implicit. Unboxing is the operation of converting a value of a reference type (previously boxed) into a value of a value type. [108] Unboxing in C# requires an explicit type cast. A boxed object of type T can only be ...
To represent substructure, one incorporates a special EAV table where the value column contains references to other entities in the system (i.e., foreign key values into the objects table). To get all the information on a given object requires a recursive traversal of the metadata, followed by a recursive traversal of the data that stops when ...
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Once in place, downstream developers can use scripts written in IronPython that interact with .NET objects in the framework, thereby extending the functionality in the framework's interface, without having to change any of the framework's code base. [32] IronPython makes extensive use of reflection. When passed in a reference to a .NET object ...
A primary key is unique throughout all stored records; only one of this key exists. [15] In other words, no duplicate may exist for any primary key. For example, an employee file might contain employee number, name, department, and salary. The employee number will be unique in the organization and will be the primary key.