SQL query return data from multiple tables

Question

I would like to know the following:

• how to get data from multiple tables in my database?
• what types of methods are there to do this?
• what are

Answer 1

You can use the concept of multiple queries in the FROM keyword. Let me show you one example:

SELECT DISTINCT e.id,e.name,d.name,lap.lappy LAPTOP_MAKE,c_loc.cnty COUNTY    
FROM  (
          SELECT c.id cnty,l.name
          FROM   county c, location l
          WHERE  c.id=l.county_id AND l.end_Date IS NOT NULL
      ) c_loc, emp e 
      INNER JOIN dept d ON e.deptno =d.id
      LEFT JOIN 
      ( 
         SELECT l.id lappy, c.name cmpy
         FROM   laptop l, company c
         WHERE l.make = c.name
      ) lap ON e.cmpy_id=lap.cmpy

You can use as many tables as you want to. Use outer joins and union where ever it's necessary, even inside table subqueries.

That's a very easy method to involve as many as tables and fields.