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  2. Set operations (SQL) - Wikipedia

    en.wikipedia.org/wiki/Set_operations_(SQL)

    A UNION query could combine results from both tables. Note that UNION ALL does not guarantee the order of rows. Rows from the second operand may appear before, after, or mixed with rows from the first operand. In situations where a specific order is desired, ORDER BY must be used. Note that UNION ALL may be much faster than plain UNION.

  3. Join (SQL) - Wikipedia

    en.wikipedia.org/wiki/Join_(SQL)

    If no matching row from the "left" table (A) exists, NULL will appear in columns from A for those rows that have no match in B. A right outer join returns all the values from the right table and matched values from the left table (NULL in the case of no matching join predicate).

  4. Relational database - Wikipedia

    en.wikipedia.org/wiki/Relational_database

    The union operator (υ) combines the tuples of two relations and removes all duplicate tuples from the result. The relational union operator is equivalent to the SQL UNION operator. The intersection operator (∩) produces the set of tuples that two relations share in common. Intersection is implemented in SQL in the form of the INTERSECT operator.

  5. SQL - Wikipedia

    en.wikipedia.org/wiki/SQL

    SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...

  6. List of set identities and relations - Wikipedia

    en.wikipedia.org/wiki/List_of_set_identities_and...

    To investigate the left distributivity of set subtraction over unions or intersections, consider how the sets involved in (both of) De Morgan's laws are all related: () = = () always holds (the equalities on the left and right are De Morgan's laws) but equality is not guaranteed in general (that is, the containment might be strict).

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  8. NFL playoff picture: Projected AFC, NFC bracket wild card ...

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    The Steelers have lost three in a row and face a Cincinnati team fighting for their slim playoff chances. Pittsburgh could be the No. 3 seed and division winner with a win and a Baltimore loss.

  9. The Commanders the lone underdog backed by bettors ... - AOL

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    Bettors like all but one favorite ahead of the NFL’s divisional round on Saturday and Sunday. The majority of money is on the Chiefs, Eagles and Ravens to cover the spread as favorites, ...