Question

Considering that I have a Schema named SBST

I want to find all empty tables list in this SBST Schema. Is there any PL/SQL procedure to find that. I found few. But those were using user tables where I was not able specify the Schema name SBST.

I was using this

select table_name from dba_tables where owner ='SBST'
having count(*)=0  group by table_name

What’s wrong in the above query?

Answer 1

Similar to @shareef’s answer, but using dynamic SQL to avoid having to create the temporary .sql file. You’ll need dbms_output to be visible, e.g. with set serveroutput on in SQL*Plus – don’t know about Toad.

declare
    cursor c(p_schema varchar2) is
        select 'select ''' || table_name || ''' from ' ||
            p_schema ||'.' || table_name || ' where rownum < 2 ' ||
            ' having count(*) = 0' as query
        from all_tables
        where owner = p_schema
        order by table_name;
    l_table all_tables.table_name%TYPE;
begin
    for r in c('SBST') loop
        begin
            execute immediate r.query into l_table;
        exception
            when no_data_found then continue;
        end;

        dbms_output.put_line(l_table);
    end loop;
end;
/

Using all_tables seems more useful than dba_tables here so you know you can select from the tables it lists. I’ve also included the schema in the from clause in case there other users have tables with the same name, and so you can still see it if you’re connected as a different user – possibly avoiding synonym issues too.

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Specifically what’s wrong with your query… you’ve got the having and group by clauses the wrong way around; but it will always return no data anyway because if SBST has any tables then count (*) from dba_tables must be non-zero, so the having always matches; and if it doesn’t then, well, there’s no data anyway so there’s nothing for the having to match against. You’re counting how many tables there are, not how many rows are in each table.