mysql - Different select statement for different condition -

this current mysql query.

current table query in sqlfiddle http://sqlfiddle.com/#!2/6e0420

if select * table, below

rn  pc  pc1 grp e_id 111 a1  a1  175 100 112 a1  a2  100 90 113 b1  b3  101 90 114 b1  b1  100 90 115 b1  b5  100 90 116 c1  c1  100 90 

but trying output

rn  pc  pc1 grp e_id 111 a1  a1  175 100 112 a1  a2   113 b1  b3   114 b1  b1  100 90 115 b1  b5   116 c1  c1  100 90 

so condition if pc=pc1 grp , e_id should shown, otherwise if pc!=pc1 grp , e_id should empty

 current query          select *         table1          rn in(select rn table1 group rn having count(*)=1)         , (pc = pc1)    solution        select rn, pc, pc1,         case when pc = pc1 grp else null end grp,        case when pc = pc1 e_id else null end e_id        table1        rn in(select rn table1 group rn having count(*)=1) 

qn2: above solution have added count = 1 because have sql query if count > 1. how combine both query, split count =1 , count >1 below sql query

select * table1  rn in(select rn table1 group rn having count(*)>1) , (pc = pc1) , grp in (select max(grp) table1) , e_id in( select min(e_id) table1) 

the conditions count>1 shld not affect count = 1 results.

i found solution already, union them. first part.

you can use case when, , display null (or else) when pc <> pc1

select rn, pc, pc1,         case when pc = pc1 grp else null end grp,        case when pc = pc1 e_id else null end e_id table1 

which can simplified (for null replacement)

select rn, pc, pc1,         case when pc = pc1 grp end grp,        case when pc = pc1 e_id  end e_id table1