[SOLVED] mysql query help

[will35010]

I have a table to store fuel info. I want to retrieve the last two records entered to calculate miles-per-gallon.

 

Here's my table:

-- Table structure for table `fuel`
--

CREATE TABLE IF NOT EXISTS `fuel` (
  `vin` varchar(20) NOT NULL,
  `mileage` mediumint(9) NOT NULL,
  `gallons` float NOT NULL,
  `total` float NOT NULL,
  `date` date NOT NULL,
  `driver` varchar(20) NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

 

I have this query but I don't know how to retrieve just the last two records. Or is there a better way to calculate it?

 

SELECT mileage, gallons FROM fuel WHERE vin = '$vin'

[ldougherty]

When you say just the last two records you mean for example you have 10 rows in the database and you want to retrieve miles and gallons for entry 9 and 10?

[will35010]

When you say just the last two records you mean for example you have 10 rows in the database and you want to retrieve miles and gallons for entry 9 and 10?

 

Correct. I just want to make sure that it will actually be the last two records. For instance if record 2 was edited, would it's number now become 10 since it was the last one edited? I only want to retrieve the last two records entered.

[Maq]

Assuming 'date' is the date when you inserted the record, you can use that to order.

 

ORDER BY `date` DESC LIMIT 2

[will35010]

Assuming 'date' is the date when you inserted the record, you can use that to order.

 

ORDER BY `date` DESC LIMIT 2

 

I thought about that but I thought I would have to do that from the php side and was trying to avoid that. I didn't know you could do it from the mysql side. Thanks!!!

[Maq]

Assuming 'date' is the date when you inserted the record, you can use that to order.

 

ORDER BY `date` DESC LIMIT 2

 

I thought about that but I thought I would have to do that from the php side and was trying to avoid that. I didn't know you could do it from the mysql side. Thanks!!!

 

In this case PHP would have nothing to do with the query except for retrieving the desired vin #.  The final query should look something similar to:

 

SELECT mileage, gallons FROM fuel WHERE vin = '$vin' ORDER BY `date` DESC LIMIT 2;

 

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Good luck.