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  2. Set operations (SQL) - Wikipedia

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

    In SQL the UNION clause combines the results of two SQL queries into a single table of all matching rows. The two queries must result in the same number of columns and compatible data types in order to unite. Any duplicate records are automatically removed unless UNION ALL is used.

  3. Relational algebra - Wikipedia

    en.wikipedia.org/wiki/Relational_algebra

    The relational algebra uses set union, set difference, and Cartesian product from set theory, and adds additional constraints to these operators to create new ones.. For set union and set difference, the two relations involved must be union-compatible—that is, the two relations must have the same set of attributes.

  4. Hierarchical and recursive queries in SQL - Wikipedia

    en.wikipedia.org/wiki/Hierarchical_and_recursive...

    Recursive CTEs are also supported by Microsoft SQL Server (since SQL Server 2008 R2), [2] Firebird 2.1, [3] PostgreSQL 8.4+, [4] SQLite 3.8.3+, [5] IBM Informix version 11.50+, CUBRID, MariaDB 10.2+ and MySQL 8.0.1+. [6] Tableau has documentation describing how CTEs can be used. TIBCO Spotfire does not support CTEs, while Oracle 11g Release 2's ...

  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. Join (SQL) - Wikipedia

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

    Specifically, any columns mentioned in the USING list will appear only once, with an unqualified name, rather than once for each table in the join. In the case above, there will be a single DepartmentID column and no employee.DepartmentID or department.DepartmentID. The USING clause is not supported by MS SQL Server and Sybase.

  7. Norovirus cases are surging. A doctor explains what to look for

    www.aol.com/norovirus-cases-surging-doctor...

    Use an internal thermometer and make sure that what you are cooking reaches the recommended temperature. Don’t eat perishable food that has been left out for more than two hours. Be sure to wash ...

  8. Union (SQL) - Wikipedia

    en.wikipedia.org/?title=Union_(SQL)&redirect=no

    Set operations (SQL)#UNION operator To a section : This is a redirect from a topic that does not have its own page to a section of a page on the subject. For redirects to embedded anchors on a page, use {{ R to anchor }} instead .

  9. Region by Region, This is What's On American's Christmas Tables

    www.aol.com/region-region-whats-americans...

    South. Ham – especially country ham – is a more common Christmas main dish in the South than elsewhere in the country, along with sides including mac & cheese and cornbread.Lechon, or spit ...