In my stored proc, I run a query like soi :
SELECT NETWORKOWNER.BUS_SEQ.NEXTVAL#LEGACYSMITH.WORLD
FROM TBLDECIDERCONTRACT#LEGACYSMITH.WORLD
WHER PROVID = 28938
How would obtaon only one NEXTVAL result?
Using dual:
SELECT NETWORKOWNER.BUS_SEQ.NEXTVAL#LEGACYSMITH.WORLD FROM dual
Or more generally: make sure your FROM and WHERE clauses result in just one row found - then NEXTVAL will be executed just once.
In addition, you can always get just a single NEXTVAL execution by invoking it natively in PL/SQL, as in:
DECLARE
l_seq INTEGER;
BEGIN
l_seq := my_sequence.NEXTVAL;
END;
Related
I have an empty table.
If I execute
select count(*) from table;
it returns 0;
However in PL/SQL, Sql*Plus
declare
c number;
begin
select count(*) into c from table;
dbms_output.put_line(c);
end;
Returns 572.
What's going on?
------------------------------------------SOLVED----------------------------------
So I had to do
delete from table;
in Sql*Plus, not in Toad.
However, I ran commit in both of them..
Commit or rollback transactions. It seems that you have been working with the table. Without commit/rollback In different sessions you will have different results.
Are you sure the SQL table has rows in it? The syntax looks correct for the SQL select. I imagine "table" will be your table name like: tblProducts? "Table" is a reserved keywork in MS SQL
Try to use i.e.:
DECLARE
c NUMBER(10) := 0;
and then:
SELECT COUNT(1) INTO c FROM table;
how can you select the same sequence twice in one query?
I have googled this and just cant get an answer.
Just to be clear, this is what I need, example :
select seq.nextval as v1, seq.nextval as v2 from dual (I know that doesn't work)
I have tried UNION as well, Just cant get my head around it.
If you always need exactly two values, you could change the sequence to increment by 2:
alter sequence seq increment by 2;
and then select the current value and its successor:
select seq.nextval,
seq.nextval + 1
from dual;
Not pretty, but it should do the job.
UPDATE
Just to clarify: the ALTER SEQUENCE should be issued only once in a lifetime, not once per session!
The Answer by Frank has a downside:
You cannot use it in transactional system, because the ALTER SEQUENCE commits any pending DML.
The Answer of Sean only pulls the sequence once.
As I understand, you want to pull two values.
As an alternative to Seans solution, you could also select two times from .nextval, due ORACLE gives you the same value twice.
I'd prefer wrapping up the sequence in a procedure.
This tricks oracle to pulling the sequence twice.
CREATE or replace FUNCTION GetSeq return number as
nSeq NUMBER;
begin
select seq.nextval into nSeq from dual;
return nSeq;
end;
/
If you need this generically, maybe you'd like:
CREATE or replace FUNCTION GetSeq(spSeq in VARCHAR2) return number as
nSeq NUMBER;
v_sql long;
begin
v_sql:='select '||upper(spSeq)||'.nextval from dual';
execute immediate v_sql into nSeq;
return nSeq;
end;
/
There are some limitations on how NEXTVAL can be used. There's a list in the Oracle docs. More to the point, the link includes a list of conditions where NEXTVAL will be called more than once.
The only scenario named on the page where a straight SELECT will call NEXTVAL more than once is in "A top-level SELECT statement". A crude query that will call NEXTVAL twice is:
SELECT seq.NEXTVAL FROM (
SELECT * FROM DUAL
CONNECT BY LEVEL <= 2) -- Change the "2" to get more sequences
Unfortunately, if you try to push this into a subquery to flatten out the values to one row with columns v1 and v2 (like in your question), you'll get the ORA-02287: sequence number not allowed here.
This is as close as I could get. If the query above won't help you get where you want, then check out the other answers that have been posted here. As I've been typing this, a couple of excellent answers have been posted.
Telling you to just call sequence.nextval multiple times would be boring, so here's what you can try:
create type t_num_tab as table of number;
CREATE SEQUENCE SEQ_TEST
START WITH 1
MAXVALUE 999999999999999999999999999
MINVALUE 1
NOCYCLE
CACHE 100
NOORDER;
create or replace function get_seq_vals(i_num in number) return t_num_tab is
seq_tab t_num_tab;
begin
select SEQ_TEST.nextval
bulk collect into seq_tab
from all_objects
where rownum <= i_num;
return seq_tab;
end;
And you can use it as follows. This example is pulling 7 numbers at once from the sequence:
declare
numbers t_num_tab;
idx number;
begin
-- this grabs x numbers at a time
numbers := get_seq_vals(7);
-- this just loops through the returned numbers
-- to show the values
idx := numbers.first;
loop
dbms_output.put_line(numbers(idx));
idx := numbers.next(idx);
exit when idx is null;
end loop;
end;
Also note that I use "next" instead of first..last as its possible you may want to remove numbers from the list before iterating through (or, sometimes a sequence cache can results in numbers incrementing by more than 1).
These are all great answers, unfortunately it was just not enough. Will definitely be able to return to this page when struggling in the future.
I have gone with a different method. Asked a new question and got my answer.
You can go check it out here.
LV_id number;
Cursor CR_test Is
select t.id
from table1 t
where t.foo = p_foo
order by t.creation_date;
Open CR_test;
Fetch CR_test
Into LV_id;
Close CR_test;
or this one :
select x.id
from(select t.id
from table1 t
where t.foo=p_foo
order by t.creation_date) x
where rownum = 1
Both above make similar result but i need known about which one is more efficient!
This is Tom Kyte's mantra:
You should do it in a single SQL statement if at all possible.
If you cannot do it in a single SQL Statement, then do it in PL/SQL.
If you cannot do it in PL/SQL, try a Java Stored Procedure.
If you cannot do it in Java, do it in a C external procedure.
If you cannot do it in a C external routine, you might want to seriously think about why it is you need to do it…
http://tkyte.blogspot.com/2006/10/slow-by-slow.html
Easiest way to find out in this case is to test your queries.
Make sure to test this yourself, indexes and data in your table may produce different results with your table.
Without any index, it looks like there is a better approach using analytic function DENSE_RANK:
SELECT MIN(id) KEEP (DENSE_RANK FIRST ORDER BY creation_date)
INTO lv_id
FROM table1
WHERE foo = p_foo;
I used the following code to test the time consumed by your queries (execute this block several times, results may vary):
DECLARE
p_foo table1.foo%TYPE := 'A';
lv_id table1.id%TYPE;
t TIMESTAMP := SYSTIMESTAMP;
BEGIN
FOR i IN 1 .. 100 LOOP
-- Query here
END LOOP;
dbms_output.put_line(SYSTIMESTAMP - t);
END;
Results:
Using cursor, fetching first row:
2.241 s
Using query with ROWNUM:
1.483 s
Using DENSE_RANK:
1.168 s
I need to forward a set of sequences with only DML access. Due to a bug in a piece of code several values were grabbed without a sequence but instead manually, so now the sequence is duplicating those values. So, I would like to push the sequence to the max value so that the next time nextval is called, it gives a value higher than the maximum. I've got about 50 sequences that each have to go a few thousand forward.
Is this possible with only DML access? If so, how should I go about it?
You should determine the difference between the next value of the sequence and the required value. The required value is typically the max value of a primary key column (let's name it ID).
DECLARE
maxid NUMBER;
maxseq NUMBER;
temp NUMBER; -- without this variable Oracle would skip to query the sequence
BEGIN
SELECT MAX(ID) INTO maxid FROM MYTABLE;
SELECT MYSEQ.NEXTVAL INTO maxseq FROM DUAL;
FOR i IN maxseq .. maxid LOOP
SELECT MYSEQ.NEXTVAL INTO temp FROM DUAL;
END LOOP;
END;
/
You can use dynamic SQL to do this. For example, this bit of code will select the next 10,000 values from each of a list of sequences.
DECLARE
l_num INTEGER;
BEGIN
FOR seq IN (select *
from all_sequences
where sequence_name in (<<list of 50 sequences>>)
and sequence_owner = <<owner of sequences>>)
LOOP
FOR i IN 1 .. 10000
LOOP
execute immediate
'select ' || seq.sequence_owner || '.' || seq.sequence_name || '.nextval from dual'
into l_num;
END LOOP;
END LOOP;
END;
If you had the ability to issue DDL against the sequence, you could use a similar approach to set the INCREMENT to 10,000, select one value from the sequence, and set the INCREMENT back down to 1 (or whatever it is now).
you can just
select seq.nextval from dual
until it is big enough...
If you have a table with at least as many rows as the amount you want to add to your sequences, the following will work. This increments each sequence by the same amount, which may not suit you, but it's quick and easy without requiring PL/SQL or the need to drop/re-create the sequence. I use it all the time when I want to get development server sequences ahead of production.
SELECT seq1.nextval, seq2.nextval, ..., seqN.nextval
FROM very_large_table
WHERE ROWNUM <= number_of_rows_to_add
To restart the sequence at a different value you need to drop and recreate it.
See the Oracle docs for ALTER SEQUENCE here.
And for CREATE SEQUENCE here
So, no I don't think it's possible with DML access, unless you just increment repeatedly like Randy suggests.
you can just;
declare
l_MaxVal pls_integer;
l_Currval pls_integer default - 1;
begin
select max(id)
into l_MaxVal
from people;
while l_Currval < l_Maxval
loop
select my_seq.nextval
into l_Currval
from dual;
end loop;
end;
There's a trick you can use to select a sequence of numbers, one per row. For example:
SELECT ROWNUM FROM DUAL CONNECT BY ROWNUM <= 100
Replace ROWNUM with <sequence>.NEXTVAL to fast-forward the sequence in large steps, for instance:
SELECT <sequence>.NEXTVAL FROM DUAL CONNECT BY ROWNUM <= 100
I wouldn't use this for making changes to a production database, but for a dev database, it may be sufficient.
I'm attempting to write a simple query where I declare some variables and then use them in a select statement in Oracle. I've been able to do this before in SQL Server with the following:
DECLARE #date1 DATETIME
SET #date1 = '03-AUG-2010'
SELECT U.VisualID
FROM Usage u WITH(NOLOCK)
WHERE U.UseTime > #Date1
From the searching I've done it appears you can not declare and set variables like this in Select statements. Is this right or am I mssing something?
From the searching I've done it appears you can not declare and set variables like this in Select statements. Is this right or am I missing something?
Within Oracle PL/SQL and SQL are two separate languages with two separate engines. You can embed SQL DML within PL/SQL, and that will get you variables. Such as the following anonymous PL/SQL block. Note the / at the end is not part of PL/SQL, but tells SQL*Plus to send the preceding block.
declare
v_Date1 date := to_date('03-AUG-2010', 'DD-Mon-YYYY');
v_Count number;
begin
select count(*) into v_Count
from Usage
where UseTime > v_Date1;
dbms_output.put_line(v_Count);
end;
/
The problem is that a block that is equivalent to your T-SQL code will not work:
SQL> declare
2 v_Date1 date := to_date('03-AUG-2010', 'DD-Mon-YYYY');
3 begin
4 select VisualId
5 from Usage
6 where UseTime > v_Date1;
7 end;
8 /
select VisualId
*
ERROR at line 4:
ORA-06550: line 4, column 5:
PLS-00428: an INTO clause is expected in this SELECT statement
To pass the results of a query out of an PL/SQL, either an anonymous block, stored procedure or stored function, a cursor must be declared, opened and then returned to the calling program. (Beyond the scope of answering this question. EDIT: see Get resultset from oracle stored procedure)
The client tool that connects to the database may have it's own bind variables. In SQL*Plus:
SQL> -- SQL*Plus does not all date type in this context
SQL> -- So using varchar2 to hold text
SQL> variable v_Date1 varchar2(20)
SQL>
SQL> -- use PL/SQL to set the value of the bind variable
SQL> exec :v_Date1 := '02-Aug-2010';
PL/SQL procedure successfully completed.
SQL> -- Converting to a date, since the variable is not yet a date.
SQL> -- Note the use of colon, this tells SQL*Plus that v_Date1
SQL> -- is a bind variable.
SQL> select VisualId
2 from Usage
3 where UseTime > to_char(:v_Date1, 'DD-Mon-YYYY');
no rows selected
Note the above is in SQLPlus, may not (probably won't) work in Toad PL/SQL developer, etc. The lines starting with variable and exec are SQLPlus commands. They are not SQL or PL/SQL commands. No rows selected because the table is empty.
I have tried this and it worked:
define PROPp_START_DT = TO_DATE('01-SEP-1999')
select * from proposal where prop_start_dt = &PROPp_START_DT
The SET command is TSQL specific - here's the PLSQL equivalent to what you posted:
v_date1 DATE := TO_DATE('03-AUG-2010', 'DD-MON-YYYY');
SELECT u.visualid
FROM USAGE u
WHERE u.usetime > v_date1;
There's also no need for prefixing variables with "#"; I tend to prefix variables with "v_" to distinguish between variables & columns/etc.
See this thread about the Oracle equivalent of NOLOCK...
Try the to_date function.
Coming from SQL Server as well, and this really bugged me. For those using Toad Data Point or Toad for Oracle, it's extremely simple. Just putting a colon in front of your variable name will prompt Toad to open a dialog where you enter the value on execute.
SELECT * FROM some_table WHERE some_column = :var_name;