how to join two tables

select * from foods,somedata;

for example food has 7 columns

some data has 3 columns

final table has 7*3 21 columns

each column of food allocated to some data all columns

SELECT Orders.OrderID, Orders.OrderDate, Customers.CustomerName

FROM Customers, Orders

WHERE Customers.CustomerName='Around the Horn' AND Customers.CustomerID=Orders.CustomerID;

orders.orderid select the table order and select the column order id customers.customername select the table customer from that select the customername table SELECT Orderid , orderdata, customers.customername columns form customers orders table to display it has to pass the conditon customer.customername is match with aroound the horn , it has 1000 records out of that It has again match with customers.customerid is equal to orders.customer id, two filters to get the results modify the names of the table SELECT o.OrderID, o.OrderDate, c.CustomerName FROM Customers AS c, Orders AS o WHERE c.CustomerName='Around the Horn' AND c.CustomerID=o.CustomerID; how to join two tables SELECT Orders.OrderID, Customers.CustomerName, Orders.OrderDate, orders.customerid, customers.customerid FROM Orders,customers where Orders.CustomerID=Customers.CustomerID; ist join tables and display who have matched two columns , that matched columns only display innerjoin SELECT Orders.OrderID, Customers.CustomerName, Orders.OrderDate FROM Orders two tables will join and display with condition INNER JOIN Customers ON Orders.CustomerID=Customers.CustomerID; inner join write from two table who has this conditon matched left join its like beofre but write only one table but matched with two tables SELECT column_name(s) FROM table1 LEFT JOIN table2 ON table1.column_name = table2.column_name; right join SELECT column_name(s) SELECT Orders.OrderID, Employees.LastName, Employees.FirstName FROM table1 FROM Orders RIGHT JOIN table2 RIGHT JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID ON table1.column_name = table2.column_name; ORDER BY Orders.OrderID; full join SELECT column_name(s) FROM table1 FULL OUTER JOIN table2 ON table1.column_name = table2.column_name WHERE condition; SELECT Customers.CustomerName, Orders.OrderID FROM Customers FULL OUTER JOIN Orders ON Customers.CustomerID=Orders.CustomerID ORDER BY Customers.CustomerName; self join SELECT A.CustomerName AS CustomerName1, B.CustomerName AS CustomerName2, A.City FROM Customers A, Customers B WHERE A.CustomerID <> B.CustomerID AND A.City = B.City ORDER BY A.City; union select a two tables, get the all elements which is common in both tables and if repeat, write only one SELECT City FROM Customers UNION SELECT City FROM Suppliers ORDER BY City; Each SELECT statement within UNION must have the same number of columns The columns must also have similar data types The columns in each SELECT statement must also be in the same order union all write duplicate values also for example we have a names with 10 times repeat, we want to know how many times it repeated SELECT COUNT(CustomerID), Country FROM Customers GROUP BY Country; I want to know on same address or same country how many body are there using group by we can know descind order write SELECT COUNT(CustomerID), Country FROM Customers GROUP BY Country ORDER BY COUNT(CustomerID) DESC; SELECT Shippers.ShipperName, COUNT(Orders.OrderID) AS NumberOfOrders FROM Orders LEFT JOIN Shippers ON Orders.ShipperID = Shippers.ShipperID GROUP BY ShipperName; ist it joins orders and shippers , to display it has condion where both ids are matched, that where both ids are matched order rows only we will show combination and left element order only we got all rows, from that rows it will show orders.orderid and shippers.shippername shippers.shippername is repeat how manytimes, that number will show and shipper name will show sql having we shown how manytimes shipper repeats, if shipper repeates greater than 5 times that willonly show SELECT COUNT(CustomerID), Country FROM Customers GROUP BY Country HAVING COUNT(CustomerID) > 5; SELECT COUNT(CustomerID), Country FROM Customers GROUP BY Country HAVING COUNT(CustomerID) > 5 ORDER BY COUNT(CustomerID) DESC; where matches at that joins means combination got, how many times repeats of last name writes andwrites if count>10 only SELECT Employees.LastName, COUNT(Orders.OrderID) AS NumberOfOrders FROM (Orders INNER JOIN Employees ON Orders.EmployeeID = Employees.EmployeeID) GROUP BY LastName HAVING COUNT(Orders.OrderID) > 10;