At a minimum, you need to query ALL_TAB_COLUMNS, not ALL_TABLES
DECLARE
match_count integer;
v_search_string varchar2(4000) := <<string you want to search for>>;
BEGIN
FOR t IN (SELECT owner, table_name, column_name FROM all_tab_columns) LOOP
EXECUTE IMMEDIATE
'SELECT COUNT(*) FROM '||t.owner || '.' || t.table_name||
' WHERE '||t.column_name||' = :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 );
END IF;
END LOOP;
END;
/
If you are looking for a string, however, you would almost certainly want to restrict yourself to looking for columns that could store a string. It wouldn’t make sense, for example, to search a DATE column for a string. And unless you have a great deal of a priori knowledge about what a BLOB column contains and the ability to parse the BLOB column’s binary formatting, it wouldn’t make sense to search a BLOB column for a string. Given that, I suspect you want something more like
DECLARE
match_count integer;
v_search_string varchar2(4000) := <<string you want to search for>>;
BEGIN
FOR t IN (SELECT owner,
table_name,
column_name
FROM all_tab_columns
WHERE data_type in ('CHAR', 'VARCHAR2', 'NCHAR', 'NVARCHAR2',
'CLOB', 'NCLOB') )
LOOP
BEGIN
EXECUTE IMMEDIATE
'SELECT COUNT(*) FROM '||t.owner || '.' || t.table_name||
' WHERE '||t.column_name||' = :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 );
END IF;
EXCEPTION
WHEN others THEN
dbms_output.put_line( 'Error encountered trying to read ' ||
t.column_name || ' from ' ||
t.owner || '.' || t.table_name );
END;
END LOOP;
END;
/
Of course, this is going to be insanely slow– you’d full scan every table once for every string column in the table. With moderately large tables and a moderate number of string columns, that is likely to take quite a while.