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  2. Set operations (SQL) - Wikipedia

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

    The SQL EXCEPT operator takes the distinct rows of one query and returns the rows that do not appear in a second result set. For purposes of row elimination and duplicate removal, the EXCEPT operator does not distinguish between NULLs. The EXCEPT ALL operator does not remove duplicates, but if a row appears X times in the first query and Y ...

  3. List of SQL reserved words - Wikipedia

    en.wikipedia.org/wiki/List_of_SQL_reserved_words

    Reserved words in SQL and related products In SQL:2023 [3] In IBM Db2 13 [4] In Mimer SQL 11.0 [5] In MySQL 8.0 [6] In Oracle Database 23c [7] In PostgreSQL 16 [1] In Microsoft SQL Server 2022 [2]

  4. Column (database) - Wikipedia

    en.wikipedia.org/wiki/Column_(database)

    For example, a database that represents company contact information might have the following columns: ID, Company Name, Address Line 1, Address Line 2, City, and Postal Code. More formally, a row is a tuple containing a specific value for each column, [ 4 ] for example: (1234, 'Big Company Inc.', '123 East Example Street', '456 West Example ...

  5. Select (SQL) - Wikipedia

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

    Rows Pagination [9] is an approach used to limit and display only a part of the total data of a query in the database. Instead of showing hundreds or thousands of rows at the same time, the server is requested only one page (a limited set of rows, per example only 10 rows), and the user starts navigating by requesting the next page, and then ...

  6. Relational database - Wikipedia

    en.wikipedia.org/wiki/Relational_database

    Codd showed that data relationships of arbitrary complexity can be represented by a simple set of concepts. [2] Part of this processing involves consistently being able to select or modify one and only one row in a table. Therefore, most physical implementations have a unique primary key (PK) for each row in a table. When a new row is written ...

  7. Relational algebra - Wikipedia

    en.wikipedia.org/wiki/Relational_algebra

    In SQL implementations, joining on a predicate is usually called an inner join, and the on keyword allows one to specify the predicate used to filter the rows. It is important to note: forming the flattened Cartesian product then filtering the rows is conceptually correct, but an implementation would use more sophisticated data structures to ...

  8. Primary key - Wikipedia

    en.wikipedia.org/wiki/Primary_key

    In the relational model of databases, a primary key is a designated attribute that can reliably identify and distinguish between each individual record in a table.The database creator can choose an existing unique attribute or combination of attributes from the table (a natural key) to act as its primary key, or create a new attribute containing a unique ID that exists solely for this purpose ...

  9. Entity–attribute–value model - Wikipedia

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

    SQL Server has limitations on row size if attempting to change the storage format of a column: the total contents of all atomic-datatype columns, sparse and non-sparse, in a row that contain data cannot exceed 8016 bytes if that table contains a sparse column for the data to be automatically copied over.