SQL stands for Structured Query Language. It is used to communicate with databases.

Databases are analogous to Spreadsheets in Excel/Google Sheets, where the tabs are called tables, and in each tab there are data organized in rows and columns. Unlike spreadsheets, databases can handle larger amounts of data, have data integrity, automate, and be used for websites and applications.

There are numerous SQL-based databases, some common options include PostgreSQL, MySQL, MariaSQL, SQLite, Oracle Databases or MS SQL Server Express. You can also use SQL on systems like Hive, Google's BigQuery, or Facebook's Presto to work with distributed data.

• SELECT column FROM table - selects the specific columns from table (e.g. * means all)
• SELECT DISTINCT(column) FROM table - call distinct on columns to remove duplicates
• SELECT COUNT(*) FROM table - called on columns to count how many rows there are
• SELECT * FROM table WHERE conditions - returns columns that only satisfy the conditions (make sure to use single quotes around strings)
• ... ORDER BY column ASC/DESC - sorts the columns based ascending or descending
• ... LIMIT how_many - limit the number of rows returned for the query
• (NOT) BETWEEN a AND b - between (not between) two conditions inclusive

Note: BETWEEN can be used with dates, but it stops on the 0:00 mark not the 23:59 mark

• WHERE color IN ('red', 'blue') - check if a value is in a list of options
• WHERE name LIKE '_Cher% - perform pattern matching, where _ represents a single character and % represents a sequence of characters (ILIKE is the case-insensitive version)