Oracle – Default value for paramteters not passed SQLPlus script

oraclesqlplus

Is there a way to set default value of paramter in sqlplus script without user input?

For example, I have an SQL script sessions.sql:

SET VERIFY OFF
SET TERMOUT OFF
DEFINE uname = '&1'

COLUMN search_uname new_value search_uname
SELECT CASE WHEN '&uname' = '' THEN '%' ELSE UPPER('&uname') END AS search_uname 
FROM dual;

SET TERMOUT ON

SELECT sid, serial, username FROM v$session WHERE username LIKE '&search_uname';

And I want to invoke it from sqlplus like this:

SQL> @sessions
Enter value for 1:

       SID    SERIAL# USERNAME
---------- ---------- ------------------------------
    56  20577 CONTEXT
.....
236 rows selected.

SQL> @sessions ""

       SID    SERIAL# USERNAME
---------- ---------- ------------------------------
    56  20577 CONTEXT
.....
236 rows selected.

SQL> @sessions SDE

       SID    SERIAL# USERNAME
---------- ---------- ------------------------------
       113  56675 SDE
       165  64881 SDE
.....
43 rows selected.

SQL>

I can only pass an empty value for parameter when I am asked to enter it, or I am able to pass an empty parameter after script name through "". But this behaviour is very annoying. Some kind of IF DEFINED "&1" will be very usefull.

Do you have any tips or tricks how this should be achieved to apply WHERE conditions in sqlplus script wheter parameter is defined or not without unnecessary user interaction?

Solution

According to the article linked by Martin I modified previous script to be working without aksing for parameter values:

SET VERIFY OFF
SET TERMOUT OFF

column 1 new_value 1
SELECT '' "1" FROM dual WHERE ROWNUM = 0;
define uname = '&1'

SET TERMOUT ON

SELECT sid, serial#, username FROM v$session 
WHERE username LIKE UPPER(DECODE('&uname', '', '%', '&uname'));

undefine 1

Best Answer

For those who don't fancy chasing and perusing links that can go away anytime, here's a quick cut'n paste snippet.

set termout on
set serveroutput on
set feedback off
set verify off

-- start
column 1 new_value 1 noprint
select '' "1" from dual where rownum = 0;
define param = &1 "default"
-- end

begin
    dbms_output.put_line ( 'Param 1 value is &param' );
end;
/

exit 0
/

Execution:

$ sqlplus -s SCOTT/TIGER@ORCL @a.sql
Param 1 value is default
$ sqlplus -s POSF/POSF@ECMDB @a.sql nondef
Param 1 value is nondef

Related Solutions

Sql – Fetch the row which has the Max value for a column

I see many people use subqueries or else window functions to do this, but I often do this kind of query without subqueries in the following way. It uses plain, standard SQL so it should work in any brand of RDBMS.

SELECT t1.*
FROM mytable t1
  LEFT OUTER JOIN mytable t2
    ON (t1.UserId = t2.UserId AND t1."Date" < t2."Date")
WHERE t2.UserId IS NULL;

In other words: fetch the row from t1 where no other row exists with the same UserId and a greater Date.

(I put the identifier "Date" in delimiters because it's an SQL reserved word.)

In case if t1."Date" = t2."Date", doubling appears. Usually tables has auto_inc(seq) key, e.g. id. To avoid doubling can be used follows:

SELECT t1.*
FROM mytable t1
  LEFT OUTER JOIN mytable t2
    ON t1.UserId = t2.UserId AND ((t1."Date" < t2."Date") 
         OR (t1."Date" = t2."Date" AND t1.id < t2.id))
WHERE t2.UserId IS NULL;

Re comment from @Farhan:

Here's a more detailed explanation:

An outer join attempts to join t1 with t2. By default, all results of t1 are returned, and if there is a match in t2, it is also returned. If there is no match in t2 for a given row of t1, then the query still returns the row of t1, and uses NULL as a placeholder for all of t2's columns. That's just how outer joins work in general.

The trick in this query is to design the join's matching condition such that t2 must match the same userid, and a greater date. The idea being if a row exists in t2 that has a greater date, then the row in t1 it's compared against can't be the greatest date for that userid. But if there is no match -- i.e. if no row exists in t2 with a greater date than the row in t1 -- we know that the row in t1 was the row with the greatest date for the given userid.

In those cases (when there's no match), the columns of t2 will be NULL -- even the columns specified in the join condition. So that's why we use WHERE t2.UserId IS NULL, because we're searching for the cases where no row was found with a greater date for the given userid.

Mysql – Unlock An Oracle Table

Option 1:

Well, one of the options is to rollback the locked SQL statement. For an instance,

lock table table1 in exclusive mode;  -- is what you should've used to lock the table.

To unlock: rollback;

Option 2:

To find username and sid:

select * from v$locked_object;

To find serial# using sid:

select * from v$session where sid= put the sid you found on v$locked_object;

To kill session:

alter system kill session 'sid, serial#'; -- Execute this command as sysdba as normal user won't have privilege.

Best Answer

Related Solutions

Sql – Fetch the row which has the Max value for a column

Mysql – Unlock An Oracle Table

Related Topic