Introduction to SQL

SQL is a high level programming language for pulling and transforming data, which are two of the most time consuming tasks in corporate finance. SQL is high level, in that the user only has to write a few lines of code to perform a massive number of calculations. This means that SQL is easy to learn, and has high utility. Finance folks can use SQL to automate much of boring parts of their jobs, and spend more time providing analysis and recommendations to management.

The main clauses of a SQL select statement are select, from, where, and group by.

Select

The “select” clause is where you list the columns of the data you want to pull, separated by commas. You can rename columns by typing “as [insert name].” You can perform calculations on data using ordinary mathematical operations.

From

The “from” clause is where you list the tables which store the data you want, separated by commas.

Where

This is where you list the table filters and join conditions. Join conditions are cross table filters used to relate tables.  

Here is a link to learn more about joins: SQL Joins

Group by

The “group by” clause is a list of columns for which you are summarizing data. Here is a link to learn more about aggregating data. Aggregating data

Simple Example

Assume there is a table named departments that has two columns- department and number_of_employees. To return the number of employees in finance you would write

"Select 

number_of_employees 

from 

departments 

where 

department = 'finance' "