内部联接中的where子句

Question

I am generating a query. I have two tables name: flights and destinations. In a flight table, I have column: id, departure, destination, price, airline, class and in destinations table that i have column: id, destination, country, region.

Now I want to get flights detail whose region is "Europe" . I am doing inner join . My query is this:

SELECT * 
FROM  `flights` 
INNER JOIN destinations ON flights.destination = destinations.destination
where region= 'europe'

Its giving me null result. if I remove ( where region= 'europe' ) from my query then it gives me the results of all the columns of flights and destinations.

Please help me out

Answer 1

Try this

SELECT * 
FROM  `flights` 
INNER JOIN destinations 
  ON flights.destination = destinations.destination
where LOWER(region) = 'europe'

Answer 2

I note that you say 'Europe' is the region. MySQL can be case-sensitive, depending on the collations being used for the database and table (but not by default). So, I would start with comparing the proper case:

SELECT * 
FROM flights f INNER JOIN 
     destinations d
     ON f.destination = d.destination
WHERE d.region = 'Europe';

If that doesn't work, then strange characters might have crept into the region column. You can try:

WHERE lower(d.region) like '%europe%'

Answer 3

Since you are using an inner join, you can specify the region as part of the join conditions, like this:

    SELECT * 
    FROM  `flights` 
    INNER JOIN destinations ON flights.destination = destinations.destination 
        AND destinations.region = 'europe'

Does the Flights.Destination value store the Id of the Destination table? You may need to adjust the join to

flights.destination = destinations.Id