Getting error ORA-06502 while creating Dynamic SQL query using procedure - oracle

Question

I have created a procedure and it requires Dynamic SQL block.
Procedure is as below which complies correctly but when I try to run it , it gives the below error.
I have tried to use cast() for all the variable which are used here. But this does not help.
Also, I am trying to run this procedure on Oracle using SQL - Developer tool.
Once the dynamic SQL is stored in sqlquery variable I would try and run the dynamic query and display its results!
**Output**
*Connecting to the database XXX.
ORA-06502: PL/SQL: numeric or value error: character to number conversion error
ORA-06512: at "XXX.PROCEDURE2", line 28
ORA-06512: at line 6
Who are you ?
Process exited.
Disconnecting from the database XXX.*
Procedure
*create or replace PROCEDURE PROCEDURE2 (var_owner IN dba_tab_cols.owner%TYPE) AS
CURSOR col_ident IS
select col1_name,col2,col3,col4,nullable,'_NM' as s_type
from table_name
where col2 in var_owner
and col3 like 'exp%%'
and col4 like 'exp2%';
sample_record col_ident%ROWTYPE;
BEGIN
OPEN col_ident;
LOOP
FETCH col_ident INTO sample_record;
DECLARE
col_nm VARCHAR2(30);
tab_nm VARCHAR2(30);
schema_nm VARCHAR2(30);
--a1 VARCHAR2(30);
sqlquery VARCHAR2(400);
BEGIN
col_nm := sample_record.col2;
tab_nm := sample_record.col3;
schema_nm := sample_record.col1_name;
IF sample_record.col4 = 'VARCHAR2' THEN
DBMS_OUTPUT.PUT_LINE('Who are you ? ');
sqlquery:= ('select distinct ' +col_nm+ 'from' + schema_nm+'.'+tab_nm + 'where rownum < 1');
DBMS_OUTPUT.PUT_LINE('Do you know me ');
END IF;
EXIT WHEN col_ident%NOTFOUND;
DBMS_OUTPUT.PUT_LINE(sample_record.col1_name||','||sample_record.col3
||','||sample_record.col2||','||sample_record.col4||','||
sample_record.col5||','||sample_record.nullable||','||
sample_record.s_type);
END;
END LOOP;
--Close CURSOR col_ident
CLOSE col_ident;
END PROCEDURE2;*