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  2. Order by - Wikipedia

    en.wikipedia.org/wiki/Order_by

    An ORDER BY clause in SQL specifies that a SQL SELECT statement returns a result set with the rows being sorted by the values of one or more columns. The sort criteria does not have to be included in the result set (restrictions apply for SELECT DISTINCT, GROUP BY, UNION [DISTINCT], EXCEPT [DISTINCT] and INTERSECT [DISTINCT].)

  3. Database index - Wikipedia

    en.wikipedia.org/wiki/Database_index

    The non-clustered index tree contains the index keys in sorted order, with the leaf level of the index containing the pointer to the record (page and the row number in the data page in page-organized engines; row offset in file-organized engines). In a non-clustered index, The physical order of the rows is not the same as the index order.

  4. Block Range Index - Wikipedia

    en.wikipedia.org/wiki/Block_Range_Index

    Table data is held in blocks or 'storage cells' on the storage servers. These storage cells are opaque to the storage server and are returned to the database engine on request, by their identifier. Previously, the database nodes must request all the storage cells in order to scan them. [6]

  5. Select (SQL) - Wikipedia

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

    The SQL SELECT statement returns a result set of rows, from one or more tables. [1] [2] 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.

  6. Join (SQL) - Wikipedia

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

    A natural join is a type of equi-join where the join predicate arises implicitly by comparing all columns in both tables that have the same column-names in the joined tables. The resulting joined table contains only one column for each pair of equally named columns. In the case that no columns with the same names are found, the result is a ...

  7. Database normalization - Wikipedia

    en.wikipedia.org/wiki/Database_normalization

    If a table in 5NF has one primary key column and N attributes, representing the same information in 6NF will require N tables; multi-field updates to a single conceptual record will require updates to multiple tables; and inserts and deletes will similarly require operations across multiple tables.

  8. Help:Sortable tables - Wikipedia

    en.wikipedia.org/wiki/Help:Sortable_tables

    A plus sign after a number breaks default numerical sorting if it is in one of the first 5 cells in a column. A plus sign in an otherwise empty cell breaks default numerical sorting of a column. That is if the cell is one of the first 5 cells in the column. You can also use 2 columns for a range if you want to sort by either the lower or upper ...

  9. Help:Creating tables - Wikipedia

    en.wikipedia.org/wiki/Help:Creating_tables

    To do so with multiple columns click the top left non-column-header cell, and then shift-click the bottom right cell. When you click on "ascending" or "descending" in the data menu the table will be sorted alphabetically. That is the default. Paste that sorted table (or just the selected columns of interest) directly into the visual editor.