Using Union All and Order By in MySQL

Question

I\'ve 2 tables:

create table advertised_products(id int,title varchar(99),timestamp timestamp);
insert advertised_products select 1,\'t1\',curdate();

create         


        

Answer 1

Wrap it in a subquery.

SELECT s.*
FROM
    (
        SELECT  ap.*, 'advertised'  as type 
        FROM advertised_products as ap
          union all
        SELECT  wp.*, 'wanted' as type 
        FROM wanted_products as wp
    ) s
ORDER BY s.timestamp desc 
limit 3

Answer 2

Error lies in here,

 "ORDER BY timestamp desc limit 3"

as you are combining the two tables query must know which fields are you using in which table.clearly that you are missing the table reference in your "orderby" clause

mention the table name/alias of the table name like below

 "ORDER BY your_table_name.timestamp desc limit 3"