Aggregating Data

• SUM: Calculate the total of a numeric column.

  `SELECT SUM(column_name) FROM table_name;` 
  

• MAX, MIN: Find the maximum and minimum values in a column.

 `SELECT MAX(column_name), MIN(column_name) FROM table_name;` 

• COUNT: Count the number of rows.

 
 `SELECT COUNT(column_name) FROM table_name;` 

• AVG: Calculate the average value.

 `SELECT AVG(column_name) FROM table_name;` 

GROUP BY and HAVING

• GROUP BY: Group rows sharing a common attribute.

 
 `SELECT column_name, COUNT(*) FROM table_name GROUP BY column_name;` 

• HAVING: Filter groups after aggregation.

 `SELECT column_name, COUNT(*) FROM table_name GROUP BY column_name HAVING COUNT(*) > 1;` 

JOINS

• INNER JOIN: Return records that have matching values in both tables.

`SELECT columns FROM table1
INNER JOIN table2 ON table1.column = table2.column;` 

• LEFT JOIN: Return all records from the left table, and the matched records from the right table.

 `SELECT columns FROM table1
 LEFT JOIN table2 ON table1.column = table2.column;` 

• RIGHT JOIN: Return all records from the right table, and the matched records from the left table.

  `SELECT columns FROM table1
  RIGHT JOIN table2 ON table1.column = table2.column;` 
  

• FULL OUTER JOIN: Return all records when there is a match in either table.

 `SELECT columns FROM table1
 FULL OUTER JOIN table2 ON table1.column = table2.column;`