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Merge Statement Part-1

 --Create Source_Student
 if object_id('Source_Student') is null
 create table Source_Student(id int identity(1,1) ,Name varchar(20)Marks int)
               
--Insert Some Sample Data to Source_Student
  insert Source_Student (Name,Marks) values('Rakesh',500)
  insert Source_Student (Name,Marks) values('Raju',400)
               
--Create Target_Student
 if object_id('Target_Student') is null
 create table Target_Student(id int ,Name varchar(20), Marks int)
               
--Insert Some Sample Data to Target_Student
  insert Target_Student (id,Name,Marks) values(1,'Rakesh',600)
  insert Target_Student (id,Name,Marks) values(3,'Nani',700)
               
  --Select Two Tables Data
   select * from Source_Student
   select * from Target_Student

In the Source table Id -1 record need to update marks column. Id-2 record need to insert in the Target Column. In the Target column Id-3 record need delete from Target column.
  --Run Merge Satement
  merge into Target_Student as trg
   using  Source_Student  as src 
   on trg.Name=Src.Name
    when matched then update
              set trg.Name=src.Name, trg.Marks=src.Marks
    when not matched then insert (id,Name,Marks)
                                    values(src.id,src.Name,src.Marks)
   when not matched by source then delete;

 Select * from Target_Student
     



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