sql - INTERSECT in MySQL

Question

I have two tables, records and data. records has multiple fields (firstname, lastname, etc.). Each of these fields is a foreign key for the data table where the actual value is stored. I need to search on multiple record fields.

Below is an example query using INTERSECT, but I need one that works in MySQL.

SELECT records.id FROM records, data WHERE data.id = records.firstname AND data.value = "john"
INTERSECT
SELECT records.id FROM records, data WHERE data.id = records.lastname AND data.value = "smith"

Thanks for any help.

Answer 1

You can use an inner join to filter for rows that have a matching row in another table:

SELECT DISTINCT records.id 
FROM records
INNER JOIN data d1 on d1.id = records.firstname AND data.value = "john"
INNER JOIN data d2 on d2.id = records.lastname AND data.value = "smith"

One of many other alternatives is an in clause:

SELECT DISTINCT records.id 
FROM records
WHERE records.firstname IN (
    select id from data where value = 'john'
) AND records.lastname IN (
    select id from data where value = 'smith'
)