具有相同列名但ID不同的2个表的视图

Question

I have 2 tables in MySQL t1 and t2. Both have same column names. Table t1 has huge data and t2 is not so huge as compared to t1 but in mean time t2 would also be of the same size as t1. The only difference is that the id column do not match in both the tables. I want to create a view out of these column.

What I have created is

CREATE VIEW vw_t1t2 AS  SELECT id , name , lastname, depid FROM t1
Union
SELECT  id , name , lastname, depid FROM t2;

If I do a query "Select * from vw_t1t2 where depid='100287'".

The view does not fetch the correct data, the data is mixture on all the records when I search for particular department id, some records are of different department id. Also it took 200 sec to execute the query.

Answer 1

you may consider to wrap the result of the union

SELECT * FROM
(
   SELECT id , name , lastname, depid FROM t1
   Union
   SELECT  id , name , lastname, depid FROM t2
) as sel1
WHERE depid = 2

but let us see the EXPLAIN output to optimize the query