is it possible in pl/sql? 2005-02-11 - By Anthony Wilson
Hi,
I only have 10g here to test on but I believe MERGE will work in 9i.
Don't know if this is any more efficient than other solutions already
offered, but it DOES get rid of the cursor looping, for better or
worse(!) and also allows for new tables which are not already present
in my_tables.
create function count_from_table(table_name in varchar2)
return number
is
cnt number(12);
begin
execute immediate 'select count(*) from '||table_name
into cnt;
return cnt;
end;
merge into my_tables m
using (select table_name from user_tables where table_name != 'MY_TABLES') n
on (m.table_name = n.table_name)
when matched then update set m.new_rows = (select count_from_table(m.table
_name) from dual)
when not matched then insert (m.table_name, m.new_rows)
values (n.table_name, (select count_from_table(n.table_name) from dual));
Now I'm sure the gurus can pick it to pieces... in fact please do. I
learn more that way...
Oh, and here is more than you ever wanted to know about count(1) vs.
count(*). Short answer, it's a myth according to the venerable Tom
Kyte. The SQL engine silently rewrites count(1) to count(*):
http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:1156159920245
cheers,
Anthony Wilson
On Wed, Feb 09, 2005 at 04:16:30PM, Guang Mei wrote:
> -- oracle 9i
> -- code works something like this now:
>
> CURSOR c_user_tables IS
> SELECT table_name FROM user_tables ;
>
> begin
> FOR x IN c_user_tables LOOP
> BEGIN
> SELECT table_name INTO dummy FROM myTables
> WHERE table_name = x.Table_Name;
> sqlstmt := 'UPDATE myTables SET new_Rows = (select count(*)
> from ' || x.Table_Name|| ') WHERE Table_Name = ' || x.Table_Name||';
> -- execute dynamic sql
> END;
> END LOOP;
> end;
> /
>
> Is there a way to get rid off the cursor looping. And
>
> 1. I don't want to use dynamic sql
> 2. I don't want to analyze user_tables
> 3. I want to update myTables is one sql statment, prefer using static sql.
>
> Possible?
--
Anthony Wilson
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