MySQL在（相同结构的）多个表中搜索ID

Question

I have products in 3 (identically structured) tables with 3 columns columns: id, date, requests. When searching for a specific product id I'd like to search in all tables (I don't know in advance in which table the product id can be found)

table1 is very large (over 100 million rows), and currently I'm using this query to create a temporary table which I use to perform other queries on.

CREATE TEMPORARY TABLE temp ENGINE=MEMORY 
as (select DISTINCT id, date, requests from table1 WHERE id='$id');

SELECT ... FROM temp

Merging the 3 tables using UNION and then look for the id takes forever due to the size of table1 (over 100 million rows), so that is not the right approach.

The fastest way I came up with is (I would do this using PHP):

search table1, if id found create temporary table, 
if id not found in table 1 then
search table2, if id found create temporary table, 
if id not found in table 2 then
search table3, if id found create temporary table, 
if id not found in table3 then return id not found. 

However this way I end up performing multiple queries (if id is located in table 3 then 4 queries will have been executed).

is there a better way of doing this with MySQL?

ADDED:

Would something like this work (what is the proper syntax for this, what I have below throws an error)

CREATE TEMPORARY TABLE temp ENGINE=MEMORY 
as (
(select DISTINCT id, date, requests from table1 WHERE id='$id')
UNION
(select DISTINCT id, date, requests from table2 WHERE id='$id')
UNION
(select DISTINCT id, date, requests from table3 WHERE id='$id')
)

Answer 1

try this
SELECT * FROM information_schema.columns WHERE column_name = 'column_name';

or

SELECT table_name, column_name FROM information_schema.columns WHERE column_name = 'column_name';