database - SQL QUERY Error :subquery returns more than one row -

i newbie sql , database learning , trying solve following database problem:

we have table 2 column name , marks. write query based on table returns grades if marks if greater 700, 'a' if less 700 , greater 500, 'b' or 'c'. main point table has 2 column.

here's query:

create table class (name varchar(20),marks int);  insert class values ("anu",1000),("abhi",100),("mittal",800),("chanchal",1200),("gurpreet",750),("somesh",1000),("sonia",600),("khushbu",450),("rashi",1100),("jyoti",550);  select * class;  

it shows following table:

| name     | marks |   | anu      |  1000 |   | abhi     |   100 |   | mittal   |   800 |   | chanchal |  1200 |   | gurpreet |   750 |   | somesh   |  1000 |   | sonia    |   600 |   | khushbu  |   450 |   | rashi    |  1100 |   | jyoti    |   550 | 

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select * class grade =(select case when marks >700 "a" when marks<700 , marks<700 "b" else "c" end grade class);  

it shows following error:

error 1242 (21000): subquery returns more 1 row

need last command.

select name ,  case when marks >700 'a' when marks<700 , marks<700 'b' else 'c' end grade class 

the above query should fulfill need , display name , grades according criteria set you. hope sql meant sql server.