What is bad in this query ?

Hi, 

What is bad in this query ? 

SELECT CASE WHEN EXIST(SELECT * FROM user WHERE name=rado)     THEN (INSERT INTO user VALUES('rado')) END; 

PostgreSQL return 

ERROR:  parser: parse error at or near "INTO"

table user have only one column 'name' .




Thanks 
-- 
Rado Petrik <r.p@szm.sk>