select * from A where A.a like '%11%'
union all
select * from B where B.a like '%11%'
union all
select * from C where C.a like '%11%'
union all
select * from D where D.a like '%11%'

------解决方案--------------------

SQL code

select * from 
(
select * from A
union all select * from B
union all select * from C
union all select * from D
) t
where t.a like '%11%';

------解决方案--------------------

SQL code
select
  *
from
  (
    select * from a union all select * from b union all select * from c union all select * from d)t
where
   a like '%11%'