Iterating all columns to find and replace a character - oracle

Question

I want to iterate through all columns to find and replace a specific character. here is my pl/sql block:
Declare
match_count Number:=0;
v_search_string VARCHAR2(4000) := '%ي%';
BEGIN
FOR t IN
(SELECT owner,
table_name,
column_name
FROM all_tab_columns
WHERE (SUBSTR(table_name,1,2)='PN'
OR (SUBSTR(table_name,1,2) ='CD'
AND owner ='PNET_USER' ))
AND (data_type ='VARCHAR2'
OR data_type ='CLOB')
)
LOOP
BEGIN
EXECUTE IMMEDIATE 'SELECT count(*) FROM '||t.owner || '.' || t.table_name|| ' WHERE '||t.column_name||' LIKE :1' INTO match_count USING v_search_string;
IF match_count > 0 THEN
dbms_output.put_line( t.owner || '.' || t.table_name ||' '||t.column_name||' '||match_count );
--EXECUTE IMMEDIATE 'UPDATE '||t.table_name||' SET '||t.column_name||'=replace()'
END IF;
END;
END LOOP;
It works fine and prints the name of columns that have the invalid characters. But I don't know how to replace the characters. How can i get the value of t.column_name , replace the invalid character and then update the t.table_name ?

Answer 1

Well it was almost fine (and stevo's answer also). I let you change v_from and v_to with your chars.
Declare
match_count Number :=0;
v_from varchar2(5) := 'a';
v_like varchar2(5) := '%'||v_from||'%';
v_to varchar2(5) := 'b';
v_sql varchar2(1000);
v_emesg varchar2(1000);
CURSOR s is
(SELECT owner, table_name, column_name
FROM all_tab_columns
where SUBSTR(table_name,1,2) IN ('PN', 'CD')
AND owner ='PNET_USER'
AND data_type IN('VARCHAR2', 'CLOB'););
begin
for t in s LOOP
begin
EXECUTE IMMEDIATE 'SELECT count(*) FROM '||t.owner || '.' || t.table_name|| ' WHERE '||t.column_name||' LIKE :1' INTO match_count USING v_like;
IF match_count > 0 THEN
begin
dbms_output.put_line( t.owner || '.' || t.table_name ||' '||t.column_name||' '||match_count );
v_sql := 'UPDATE '||t.owner||'.'||t.table_name||' SET '||t.column_name||'= REPLACE('||t.column_name||', '''||v_from||''', '''||v_to||''') WHERE '||t.column_name||' LIKE '''|| v_like||'''';
dbms_output.put_line(v_sql);
EXECUTE IMMEDIATE v_sql;
EXCEPTION WHEN OTHERS THEN
v_emesg := SQLERRM;
dbms_output.put_line(v_emesg);
dbms_output.put_line('Errow while trying to update '||t.owner||'.'||.t.table_name||' : column '||t.column_name||'.';
END;
END IF;
end;
END LOOP;
end;

Answer 2

Something like
EXECUTE IMMEDIATE 'UPDATE '||t.table_name||' SET '||t.column_name||'=replace('||t.column_name||',''FROM'',''TO'')'
Should do it, where FROM is the invalid character and TO is whatever you want to change it to.
See oracle docs in link for an explanation of how REPLACE works.
http://docs.oracle.com/cd/B19306_01/server.102/b14200/functions134.htm.
NB I don't have anywhere to try this, so syntax might not be correct.