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  2. dplyr - Wikipedia

    en.wikipedia.org/wiki/Dplyr

    select(), which is used to subset a dataframe by its columns; arrange() , which is used to sort rows in a dataframe based on attributes held by particular columns; mutate() , which is used to create new variables, by altering and/or combining values from existing columns; and

  3. Table (database) - Wikipedia

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

    In a database, a table is a collection of related data organized in table format; consisting of columns and rows.. In relational databases, and flat file databases, a table is a set of data elements (values) using a model of vertical columns (identifiable by name) and horizontal rows, the cell being the unit where a row and column intersect. [1]

  4. Wide and narrow data - Wikipedia

    en.wikipedia.org/wiki/Wide_and_narrow_data

    The process of converting a narrow table to wide table is generally referred to as "pivoting" in the context of data transformations. The "pandas" python package provides a "pivot" method which provides for a narrow to wide transformation.

  5. Cursor (databases) - Wikipedia

    en.wikipedia.org/wiki/Cursor_(databases)

    In SQL procedures, a cursor makes it possible to define a result set (a set of data rows) and perform complex logic on a row by row basis. By using the same mechanics, a SQL procedure can also define a result set and return it directly to the caller of the SQL procedure or to a client application.

  6. Select (SQL) - Wikipedia

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

    Select only then {rows} rows with filter: First Page: select only the first {rows} rows, depending on the type of database; Next Page: select only the first {rows} rows, depending on the type of database, where the {unique_key} is greater than {last_val} (the value of the {unique_key} of the last row in the current page)

  7. Unique key - Wikipedia

    en.wikipedia.org/wiki/Unique_key

    When the data model is instantiated into a physical database, it is the key that the system uses the most when accessing the table, or joining the tables together when selecting data. Alternate A non-primary key that can be used to identify only one row in a table. Alternate keys may be used like a primary key in a single-table select. Foreign

  8. Aggregate function - Wikipedia

    en.wikipedia.org/wiki/Aggregate_function

    The listagg function, as defined in the SQL:2016 standard [2] aggregates data from multiple rows into a single concatenated string. In the entity relationship diagram , aggregation is represented as seen in Figure 1 with a rectangle around the relationship and its entities to indicate that it is being treated as an aggregate entity.

  9. Row (database) - Wikipedia

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

    A database table can be thought of as consisting of rows and columns. [1] Each row in a table represents a set of related data, and every row in the table has the same structure. For example, in a table that represents companies, each row might represent a single company. Columns might represent things like company name, address, etc.