WEEK 4 - Power Query and SQL Query

Power Query: Left Outer

All rows from left and matching from right

Power Query: Full Outer

All rows from both: matching and not matching

Power Query: Right Outer

All rows from right and matching from left

Power Query: Left Anti

Not matching rows from left

Power Query: Inner

Only matching rows

Power Query: Right Anti

Not matching rows from right

Structured Query Language (SQL)

• Standard language for querying and manipulating data

• Can handl big data sets

SQL: SELECT

Defines which varaibles/fields that you want

SQL: FROM

Defines table you are pulling from

SQL: ORDER BY

Orders data by ascending (ASC) unless descending (DESC) is specified

• Must be last line in a query

SQL: AS

Gives an informative name to the aggregate value

SQL: WHERE

Filter to find rows/observations that match specified criteria BEFORE grouping

SQL: HAVING

Filter to find aggregate values that match specified criteria AFTER grouping