plsql - oracle sql dynamic query to select column in cursor -

i've declared below cursor , variables:

l_level           varchar2(100); l_level_value     varchar2(100); l_select_clause   clob; cursor l_data     select level1, level2, level3        levels; 

then loop through cursor:

for c1line in l_data loop     case when c1line.level1 null l_level := 'c1line.level2'          when c1line.level2 null l_level := 'c1line.level3'          when c1line.level3 null l_level := 'c1line.level4'          else l_level := null     end case; end loop;  l_select_clause := 'select ' || l_level || ' l_level_value dual;';  execute immediate l_select_clause; 

and have other statements execute depending on selected variable l_level_value

my problem when execute procedure following error:

ora-00904: "c1line"."level2": invalid identifier ora-06512: @ "my_procedure", line 110 ora-06512: @ line 2

does know have done wrong? thanks

about actual error c1line.level1 , open cursor dynamically? seems valid in thee code have shown

then..

execute immediate accepts bind variable, whereas should after execution only. mention, semicolon (;) not needed in query string

l_select_clause := 'select ' || l_level || '  dual';  execute immediate l_select_clause l_level_value;