Getting matches from multiple tables in MySQL - mysql

Question

How can i return the matches of two tables.
Table 1:
CREATE TABLE `lost` (
`id` int(11) NOT NULL,
`firstName` int(100) NOT NULL,
`lastName` varchar(100) NOT NULL,
`country` varchar(2) NOT NULL,
`address` varchar(100) NOT NULL,
`email` varchar(120) NOT NULL,
`color` varchar(32) NOT NULL,
`location` varchar(100) NOT NULL,
`airport` int(11) NOT NULL,
`dateReported` date NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Table 2:
CREATE TABLE `found` (
`id` int(11) NOT NULL,
`firstName` int(100) NOT NULL,
`lastName` varchar(100) NOT NULL,
`country` varchar(2) NOT NULL,
`address` varchar(100) NOT NULL,
`email` varchar(120) NOT NULL,
`color` varchar(32) NOT NULL,
`location` varchar(100) NOT NULL,
`airport` int(11) NOT NULL,
`dateReported` date NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Now i want to create a query which selects all fields which have any matches on both tables.
And if possible another row which says how many matching fields it has per row.

Answer 1

Not sure I understood, is this what you want?
SELECT t.*,s.*,
(t.firstName = s.firstName ) +
(t.lastName = s.lastName) +
(t.country = s.country) +
(t.address = s.address) +
..... as how_many_matches
FROM `lost` t
JOIN `found` s
ON(t.id = s.id)
MySQL evaluates Boolean expressions as 1 for TRUE and 0 for FALSE , so can you just sum up the comparisons of the columns.
Note that both of your tables are exactly the same, this is not a recommended design. I advise you to add another column TYPE that will save lost / found and combine the two tables .