[Querying and Filtering Data]

Querying Data

The first task a data analyst performs when working with data.

SQL

A tool used by data analysts to query data.

Graphical Data Tools

Tools like SQL Server Management Studio and Tableau used for querying data.

Unique Identifiers

Product IDs that can be difficult to understand without additional information.

Joining Tables

Merging data from multiple tables to make reports more informative.

Inner Join

Returns only the matching rows between two tables.

Left Outer Join

Returns all the records from the left table and matching records from the right, with nulls for non-matches.

Right Outer Join

Returns all the records from the right table and matching records from the left, with nulls for non-matches.

Full Outer Join

Returns all records from both tables, with nulls for unmatched data.

Cross Join

Returns the cartesian product of two tables.

Primary Purpose of Filtering Data

To restrict the rows in a dataset based on a condition.

Where Clause

SQL clause commonly used to filter data.

Parameterization

Using parameters in queries to allow dynamic values.

Indexing

Creating a data structure to improve speed and efficiency of data retrieval.

Temporary Table

A table that exists only within a session and is deleted upon disconnect.

Nested Query or Subquery

A query within another SQL query used to simplify complex queries.

Query Execution Plan

A visualization of the order in which a query is executed.