SQL查询以合并具有不同列数的多个表

Question

I have several tables with the first three rows identical and the rest different (in numbers as well). I want to union all tables into one, with first three columns as they are and the rest concatenated together into a single column named as "description". Now, I was able to do this manually but i have lots of tables. can a while loop be used, with variables? or is it doable?

Answer 1

It sounds like you want to join the tables together. In MySQL, this would look like:

select t1.col1, t1.col2, t1.col3,
       concat(t1.col4, t2.col4, t3.col4) as description
from t1 left outer join
     t2
     on t1.col1 = t2.col1 and t1.col2 = t2.col2 and t1.col3 = t2.col3 left outer join
     t3
     on t1.col1 = t3.col1 and t1.col2 = t3.col2 and t1.col3 = t3.col3