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  2. Nested set model - Wikipedia

    en.wikipedia.org/wiki/Nested_set_model

    The standard relational algebra and relational calculus, and the SQL operations based on them, are unable to express directly all desirable operations on hierarchies. The nested set model is a solution to that problem. An alternative solution is the expression of the hierarchy as a parent-child relation. Joe Celko called this the adjacency list ...

  3. Database schema - Wikipedia

    en.wikipedia.org/wiki/Database_schema

    The database schema is the structure of a database described in a formal language supported typically by a relational database management system (RDBMS). The term " schema " refers to the organization of data as a blueprint of how the database is constructed (divided into database tables in the case of relational databases ).

  4. Tree (abstract data type) - Wikipedia

    en.wikipedia.org/wiki/Tree_(abstract_data_type)

    If of a fixed size, the nodes might be stored in a list. Nodes and relationships between nodes might be stored in a separate special type of adjacency list. In relational databases, nodes are typically represented as table rows, with indexed row IDs facilitating pointers between parents and children.

  5. B-tree - Wikipedia

    en.wikipedia.org/wiki/B-tree

    A B-tree index creates a multi-level tree structure that breaks a database down into fixed-size blocks or pages. Each level of this tree can be used to link those pages via an address location, allowing one page (known as a node, or internal page) to refer to another with leaf pages at the lowest level.

  6. SQL syntax - Wikipedia

    en.wikipedia.org/wiki/SQL_syntax

    Each column in an SQL table declares the type(s) that column may contain. ANSI SQL includes the following data types. [14] Character strings and national character strings. CHARACTER(n) (or CHAR(n)): fixed-width n-character string, padded with spaces as needed; CHARACTER VARYING(n) (or VARCHAR(n)): variable-width string with a maximum size of n ...

  7. Flat-file database - Wikipedia

    en.wikipedia.org/wiki/Flat-file_database

    This is also called indentation or "fixed-width" data formatting. Another common convention is to separate columns using one or more delimiter characters, such as a tab or comma . Relational algebra: Each row or record in the above table meets the standard definition of a tuple under relational algebra (the above example depicts a series of 3 ...

  8. Fantasy football Start 'Em, Sit 'Em: 40 players to start or ...

    www.aol.com/fantasy-football-start-em-sit...

    The Dolphins are middle of the road defending tight ends but have allowed the fifth-most receptions per game (5.7) to the position. Continue to ride Henry with the rookie quarterback leaning on him.

  9. Entity–attribute–value model - Wikipedia

    en.wikipedia.org/wiki/Entity–attribute–value...

    An entity–attribute–value model (EAV) is a data model optimized for the space-efficient storage of sparse—or ad-hoc—property or data values, intended for situations where runtime usage patterns are arbitrary, subject to user variation, or otherwise unforeseeable using a fixed design.