试试这个查询-
SELECT
t2.company_name,
t2.expose_new,
t2.expose_used,
t1.title,
t1.seller,
t1.status,
CASE status
WHEN 'New' THEN t2.expose_new
WHEN 'Used' THEN t2.expose_used
ELSE NULL
END as 'expose'
FROM
`products` t1
JOIN manufacturers t2
ON
t2.id = t1.seller
WHERE
t1.seller = 4238
602392714
清零编程群