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The data complexity is the computational complexity when the query is fixed and when the input is just the database. For instance, we say that query evaluation has polynomial-time data complexity for a class of queries if, for every fixed query Q in that class, given a database D, we can compute the answers to Q on D in polynomial time.
In Oracle SQL, most operations and searches are case-sensitive by default, [6] while in most other DBMSes, SQL searches are case-insensitive by default. [ 7 ] Case-insensitive operations are sometimes said to fold case , from the idea of folding the character code table so that upper- and lowercase letters coincide.
To allow several users to edit a database table at the same time and also prevent inconsistencies created by unrestricted access, a single record can be locked when retrieved for editing or updating. Anyone attempting to retrieve the same record for editing is denied write access because of the lock (although, depending on the implementation ...
The terms schema matching and mapping are often used interchangeably for a database process. For this article, we differentiate the two as follows: schema matching is the process of identifying that two objects are semantically related (scope of this article) while mapping refers to the transformations between the objects. For example, in the ...
A CSS width setting for the overall table in desktop view acts like width settings on divs and tables on webpages outside Wikipedia. A horizontal scrollbar is created when the screen is too narrow for the width setting. See width outside Wikipedia: width - CSS: Cascading Style Sheets | MDN; CSS width Property.
In SQL (Structured Query Language), the term cardinality refers to the uniqueness of data values contained in a particular column (attribute) of a database table. The lower the cardinality, the more duplicated elements in a column. Thus, a column with the lowest possible cardinality would have the same value for every row.
Object–relational impedance mismatch is a set of difficulties going between data in relational data stores and data in domain-driven object models. Relational Database Management Systems (RDBMS) is the standard method for storing data in a dedicated database, while object-oriented (OO) programming is the default method for business-centric design in programming languages.
A SELECT statement retrieves zero or more rows from one or more database tables or database views. In most applications, SELECT is the most commonly used data manipulation language (DML) command. As SQL is a declarative programming language, SELECT queries specify a result set, but do not specify how to calculate it.