编写SQL查询

Question

I have two tables:

product_description( name , product_id )

product( quantity, stock_status_id, price, product_id )

What I am trying to do is run a query that will get me the above data but I am not sure how to implement a join to get the joined data from both tables.

Resolved

I did the following:

SELECT product_description.name, product.quantity,product.price
FROM product
INNER JOIN product_description
ON product.product_id=product_description.product_id
ORDER BY product_description.name 

Answer 1

Operating under the assumption that you have matching product_id s in each table, here's a query that will return the data you need using implicit joins:

SELECT product.product_id, name, quantity, stock_status_id, price
FROM product, product_description
WHERE product.product_id = product_description.product_id

UPDATE:

This works as I would expect. Here are two table dumps that might help you, and the output of the query.

product table:

--
-- Table structure for table `product`
--

CREATE TABLE IF NOT EXISTS `product` (
  `product_id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(256) COLLATE utf8_unicode_ci NOT NULL,
  PRIMARY KEY (`product_id`)
) ENGINE=MyISAM  DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci AUTO_INCREMENT=3 ;

--
-- Dumping data for table `product`
--

INSERT INTO `product` (`product_id`, `name`) VALUES
(1, 'Croissant'),
(2, 'Danish');

product_description table:

--
-- Table structure for table `product_description`
--

CREATE TABLE IF NOT EXISTS `product_description` (
  `product_id` int(11) NOT NULL,
  `quantity` int(11) NOT NULL,
  `stock_status_id` int(11) NOT NULL,
  `price` double NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

--
-- Dumping data for table `product_description`
--

INSERT INTO `product_description` (`product_id`, `quantity`, `stock_status_id`, `price`) VALUES
(1, 6, 2, 12.5),
(2, 13, 1, 19.25);

Output from the above query:

"1","Croissant","6","2","12.5"
"2","Danish","13","1","19.25"

Answer 2

maybe something like this?

select p.id, p.quantity, p.stock_status_id, p.price, d.name
from Product p inner join `Product Description` d on d.product_id=p.id

although I'm still not sure of what the table schema actually looks like from the description in the question.

Answer 3

SELECT
   -- name each column you want here
   -- prefix columns from the PRODUCT table with its alias like so:
   p.product_id,

   -- prefix columns from the other table as its alias
   d.quantity
FROM
    PRODUCT p  -- name of your PRODUCT table aliased as p
INNER JOIN     -- join against your other table
    PRODUCT_DESCRIPTION d -- name of your other table aliased as d
ON
    p.product_id = d.product_id -- match the foreign keys

See INNER JOIN documentation for more details.

NOTE: This won't work as-is, you'll need to provide the columns that you want from each table in the SELECT clause, and probably fix the table names to match for your application.