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  2. pandas (software) - Wikipedia

    en.wikipedia.org/wiki/Pandas_(software)

    [4]: 114 A DataFrame is a 2-dimensional data structure of rows and columns, similar to a spreadsheet, and analogous to a Python dictionary mapping column names (keys) to Series (values), with each Series sharing an index. [4]: 115 DataFrames can be concatenated together or "merged" on columns or indices in a manner similar to joins in SQL.

  3. Comma-separated values - Wikipedia

    en.wikipedia.org/wiki/Comma-separated_values

    CSV is a delimited data format that has fields/columns separated by the comma character and records/rows terminated by newlines. A CSV file does not require a specific character encoding, byte order, or line terminator format (some software do not support all line-end variations). A record ends at a line terminator.

  4. Database index - Wikipedia

    en.wikipedia.org/wiki/Database_index

    The order that the index definition defines the columns in is important. It is possible to retrieve a set of row identifiers using only the first indexed column. However, it is not possible or efficient (on most databases) to retrieve the set of row identifiers using only the second or greater indexed column.

  5. Data definition language - Wikipedia

    en.wikipedia.org/wiki/Data_definition_language

    The DROP statement destroys an existing database, table, index, or view. A DROP statement in SQL removes a component from a relational database management system (RDBMS). The types of objects that can be dropped depends on which RDBMS is being used, but most support the dropping of tables , users , and databases .

  6. Pivot table - Wikipedia

    en.wikipedia.org/wiki/Pivot_table

    Column labels are used to apply a filter to one or more columns that have to be shown in the pivot table. For instance if the "Salesperson" field is dragged to this area, then the table constructed will have values from the column "Sales Person", i.e., one will have a number of columns equal to the number of "Salesperson". There will also be ...

  7. List (abstract data type) - Wikipedia

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

    A list may contain the same value more than once, and each occurrence is considered a distinct item. A singly-linked list structure, implementing a list with three integer elements. The term list is also used for several concrete data structures that can be used to implement abstract lists, especially linked lists and arrays.

  8. Help:Columns - Wikipedia

    en.wikipedia.org/wiki/Help:Columns

    To create columns in an article one may use {} and {}. Note that this is not supported by Internet Explorer version 9 and below or Opera version 11 and below — see {{ Div col }} for details. To illustrate the use of these templates, this example uses the {{ lorem }} template to generate Lorem ipsum placeholder text.

  9. Database schema - Wikipedia

    en.wikipedia.org/wiki/Database_schema

    The formal definition of a database schema is a set of formulas (sentences) called integrity constraints imposed on a database. [citation needed] These integrity constraints ensure compatibility between parts of the schema. All constraints are expressible in the same language.