Question

Table1

t1Id
t1Name

Table2

t2Id
t2Name

Table1_Table2_Mapping

t1Id
t2Id

In this below query, as a second column in output, I want the t2Name Column where Having COUNT(t1Id) = 1 and I want some fixed value (‘Common’) where Having COUNT(t1Id) > 1

Select t1Id 
from Table1_Table2_Mapping
Group By t1Id

Thanks in advance.

Answer 1

SELECT m.t1Id,
       CASE
         WHEN COUNT(*) = 1 THEN MAX(t2.t2Name)
         ELSE 'Common'
       END
FROM   Table1_Table2_Mapping m
       JOIN Table2 t2
         ON t2.t2Id = m.t2Id
GROUP  BY m.t1Id