SELECT data FROM two tables in MySQL

Question

What I have: The next structure:

table_zero
-> id (PRIMARY with auto increment)
-> other

Answer 1

Try this

SELECT *
FROM 
(
SELECT table_zero.id AS ID, table_1.varchar_field AS field
FROM table_zero
  JOIN table_1 ON table_zero.id = table_1.id
WHERE table_1.varchar_field LIKE '%str%'
UNION
SELECT table_zero.id, table_2.varchar_field  AS field
FROM table_zero
  JOIN table_2 ON table_zero.id = table_2.id
) tbl
WHERE 
tbl.field LIKE '%str%'