Execute Immediate in oracle - oracle

Question

I have below query which gives an error as encounter an symbol ( in the line where loop is used. I am trying to develop a function which takes dynamic paramater as table_name,column_name,table_id and used for other tables as well.
FUNCTION get_encryp_pass( table_name IN varchar2,column_name IN varchar2,table_id IN varchar2) RETURN VARCHAR2
IS
BEGIN
EXECUTE IMMEDIATE 'for c1 in (select * from' || table_name ||) loop
EXECUTE IMMEDIATE 'update ' || table_name || ' set ' || column_name = encrypt_val(c1.column_name) || ' where ' || table_id || ' = ' || c1.table_id and column_name is not null;
end loop;
END get_encrypt_pass;

Answer 1

this should work:
CREATE PROCEDURE get_encryp_pass(table_name IN varchar2,
column_name IN varchar2,
table_id IN varchar2) IS
BEGIN
EXECUTE IMMEDIATE 'begin for c1 in (select * from ' || table_name ||
') loop update ' || table_name || ' set ' ||
column_name || ' = encrypt_val(c1.' || column_name ||
') where ' || table_id || ' = c1.'||table_id||' and ' || column_name ||
' is not null; end loop; end;'
;
END;
But why not simply call update FTP_SFTP_SERVER set PASSWORD=encrypt_val(PASSWORD) where PASSWORD is not null ?

Answer 2

keep care of what is a variable and what is a string-literal and must be single-quoted therefore ... and string-variables mus be double-quoted:
EXECUTE IMMEDIATE 'update ' || table_name || ' set ' || column_name || ' = ''' || encrypt_val(c1.column_name) || ''' where ' || table_id || ' = ' || c1.table_id || ' and column_name is not null';
Best practice is to concatenate the statement in a varchar2-variable first and inspect this. If the content of the variable is syntactical correct and executable, the EXECUTE IMMEDIATE should work as well
declare
stmt varchar2(4000);
begin
stmt := 'update ' || table_name || ' set ' || column_name || ' = ''' || encrypt_val(c1.column_name) || ''' where ' || table_id || ' = ' || c1.table_id || ' and column_name is not null';
EXECUTE IMMEDIATE stmt;
end;

Answer 3

I think i have one alternative for your question. MERGE can be used in this case. Please try it i dont have workspaceso dint test it but it should work Let me know if it helps.
FUNCTION get_encryp_pass(
table_name IN VARCHAR2,
column_name IN VARCHAR2,
table_id IN VARCHAR2)
RETURN VARCHAR2
IS
BEGIN
EXECUTE IMMEDIATE 'MERGE INTO '||table_name||' t1 USING
(
SELECT * FROM '||table_name|| ')t2
ON
(
t1.table_id = t2.table_id
)
WHEN MATCHED THEN
UPDATE SET t1.'||column_name||' = encrypt_val(t2.'||column_name||')'
||' WHERE and t1.'||column_name||' IS NOT NULL';
END;