How to split column with delimiter into two columns in SQL Server Split

We can use Case and  CHARINDEX to split column with delimiter into two columns in SQL Server

select 
    case when CHARINDEX('_',name)>0 
         then SUBSTRING(name,1,CHARINDEX('_',name)-1) 
         else name end firstname, 
    CASE WHEN CHARINDEX('_',name)>0 
         THEN SUBSTRING(name,CHARINDEX('_',name)+1,len(name))  
         ELSE NULL END as lastname
from emp

you can use CASE command to control is last name available.

MS SQL Server:

Query 1:

declare @t table (id int, name  varchar(50))

insert into @t (id,name) values( 1    ,'abc_rao')
insert into @t (id,name) values( 2    ,'nani')
insert into @t (id,name) values( 3    ,'hari_babu')
insert into @t (id,name) values( 4    ,'kalibabu')
insert into @t (id,name) values( 5    ,'ab_tan')

select 
    case when CHARINDEX('_',name)>0 
         then SUBSTRING(name,1,CHARINDEX('_',name)-1) 
         else name end firstname, 
    CASE WHEN CHARINDEX('_',name)>0 
         THEN SUBSTRING(name,CHARINDEX('_',name)+1,len(name))  
         ELSE NULL END as lastname
from @t

Results:

| FIRSTNAME | LASTNAME |
|-----------|----------|
|       abc |      rao |
|      nani |   (null) |
|      hari |     babu |
|  kalibabu |   (null) |
|        ab |      tan |