如何声明变量并在同一个 Oracle SQL 脚本中使用它？

Question

I want to write reusable code and need to declare some variables at the beginning and reuse them in the script, such as:

DEFINE stupidvar = 'stupidvarcontent';

SELECT stupiddata
FROM stupidtable
WHERE stupidcolumn = &stupidvar;

How can I declare a variable and reuse it in statements that follow such as in using it SQLDeveloper.

---

Attempts

• Use a DECLARE section and insert the following SELECT statement in BEGIN and END; . Acces the variable using &stupidvar .
• Use the keyword DEFINE and access the variable.
• Using the keyword VARIABLE and access the the variable.

But I am getting all kinds of errors during my tries (Unbound variable, Syntax error, Expected SELECT INTO ...).

Answer 1

There are a several ways of declaring variables in SQL*Plus scripts.

The first is to use VAR, to declare a bind variable. The mechanism for assigning values to a VAR is with an EXEC call:

SQL> var name varchar2(20)
SQL> exec :name := 'SALES'

PL/SQL procedure successfully completed.

SQL> select * from dept
  2  where dname = :name
  3  /

    DEPTNO DNAME          LOC
---------- -------------- -------------
        30 SALES          CHICAGO

SQL>

A VAR is particularly useful when we want to call a stored procedure which has OUT parameters or a function.

Alternatively we can use substitution variables. These are good for interactive mode:

SQL> accept p_dno prompt "Please enter Department number: " default 10
Please enter Department number: 20
SQL> select ename, sal
  2  from emp
  3  where deptno = &p_dno
  4  /
old   3: where deptno = &p_dno
new   3: where deptno = 20

ENAME             SAL
---------- ----------
CLARKE            800
ROBERTSON        2975
RIGBY            3000
KULASH           1100
GASPAROTTO       3000

SQL>

When we're writing a script which calls other scripts it can be useful to DEFine the variables upfront. This snippet runs without prompting me to enter a value:

SQL> def p_dno = 40
SQL> select ename, sal
  2  from emp
  3  where deptno = &p_dno
  4  /
old   3: where deptno = &p_dno
new   3: where deptno = 40

no rows selected

SQL>

Finally there's the anonymous PL/SQL block. As you see, we can still assign values to declared variables interactively:

SQL> set serveroutput on size unlimited
SQL> declare
  2      n pls_integer;
  3      l_sal number := 3500;
  4      l_dno number := &dno;
  5  begin
  6      select count(*)
  7      into n
  8      from emp
  9      where sal > l_sal
 10      and deptno = l_dno;
 11      dbms_output.put_line('top earners = '||to_char(n));
 12  end;
 13  /
Enter value for dno: 10
old   4:     l_dno number := &dno;
new   4:     l_dno number := 10;
top earners = 1

PL/SQL procedure successfully completed.

SQL>

Answer 2

Try using double quotes if it's a char variable:

DEFINE stupidvar = "'stupidvarcontent'";

or

DEFINE stupidvar = 'stupidvarcontent';

SELECT stupiddata  
FROM stupidtable  
WHERE stupidcolumn = '&stupidvar'

upd:

SQL*Plus: Release 10.2.0.1.0 - Production on Wed Aug 25 17:13:26 2010

Copyright (c) 1982, 2005, Oracle.  All rights reserved.

SQL> conn od/od@etalon
Connected.
SQL> define var = "'FL-208'";
SQL> select code from product where code = &var;
old   1: select code from product where code = &var
new   1: select code from product where code = 'FL-208'

CODE
---------------
FL-208

SQL> define var = 'FL-208';
SQL> select code from product where code = &var;
old   1: select code from product where code = &var
new   1: select code from product where code = FL-208
select code from product where code = FL-208
                                      *
ERROR at line 1:
ORA-06553: PLS-221: 'FL' is not a procedure or is undefined

Answer 3

In PL/SQL v.10

keyword declare is used to declare variable

DECLARE stupidvar varchar(20);

to assign a value you can set it when you declare

DECLARE stupidvar varchar(20) := '12345678';

or to select something into that variable you use INTO statement, however you need to wrap statement in BEGIN and END , also you need to make sure that only single value is returned, and don't forget semicolons.

so the full statement would come out following:

DECLARE stupidvar varchar(20);
BEGIN
    SELECT stupid into stupidvar FROM stupiddata CC 
    WHERE stupidid = 2;
END;

Your variable is only usable within BEGIN and END so if you want to use more than one you will have to do multiple BEGIN END wrappings

DECLARE stupidvar varchar(20);
BEGIN
    SELECT stupid into stupidvar FROM stupiddata CC 
    WHERE stupidid = 2;

    DECLARE evenmorestupidvar varchar(20);
    BEGIN
        SELECT evenmorestupid into evenmorestupidvar FROM evenmorestupiddata CCC 
        WHERE evenmorestupidid = 42;

        INSERT INTO newstupiddata (newstupidcolumn, newevenmorestupidstupidcolumn)
        SELECT stupidvar, evenmorestupidvar 
        FROM dual

    END;
END;

Hope this saves you some time

Answer 4

If you want to declare date and then use it in SQL Developer.

DEFINE PROPp_START_DT = TO_DATE('01-SEP-1999')

SELECT * 
FROM proposal 
WHERE prop_start_dt = &PROPp_START_DT

Answer 5

Just want to add Matas ' answer. Maybe it's obvious, but I've searched for a long time to figure out that the variable is accessible only inside the BEGIN-END construction, so if you need to use it in some code later, you need to put this code inside the BEGIN-END block .

Note that these blocks can be nested :

DECLARE x NUMBER;
BEGIN
    SELECT PK INTO x FROM table1 WHERE col1 = 'test';

    DECLARE y NUMBER;
    BEGIN
        SELECT PK INTO y FROM table2 WHERE col2 = x;

        INSERT INTO table2 (col1, col2)
        SELECT y,'text'
        FROM dual
        WHERE exists(SELECT * FROM table2);

        COMMIT;
    END;
END;

Answer 6

The question is about to use a variable in a script means to me it will be used in SQL*Plus.

The problem is you missed the quotes and Oracle can not parse the value to number.

SQL> DEFINE num = 2018
SQL> SELECT &num AS your_num FROM dual;
old   1: SELECT &num AS your_num FROM dual
new   1: SELECT 2018 AS your_num FROM dual

  YOUR_NUM
----------
      2018

Elapsed: 00:00:00.01

This sample is works fine because of automatic type conversion (or whatever it is called).

If you check by typing DEFINE in SQL*Plus, it will shows that num variable is CHAR.

SQL>define
DEFINE NUM             = "2018" (CHAR)

It is not a problem in this case, because Oracle can deal with parsing string to number if it would be a valid number.

When the string can not parse to number, than Oracle can not deal with it.

SQL> DEFINE num = 'Doh'
SQL> SELECT &num AS your_num FROM dual;
old   1: SELECT &num AS your_num FROM dual
new   1: SELECT Doh AS your_num FROM dual
SELECT Doh AS your_num FROM dual
       *
ERROR at line 1:
ORA-00904: "DOH": invalid identifier

With a quote, so do not force Oracle to parse to number, will be fine:

17:31:00 SQL> SELECT '&num' AS your_num FROM dual;
old   1: SELECT '&num' AS your_num FROM dual
new   1: SELECT 'Doh' AS your_num FROM dual

YOU
---
Doh

So, to answer the original question, it should be do like this sample:

SQL> DEFINE stupidvar = 'X'
SQL>
SQL> SELECT 'print stupidvar:' || '&stupidvar'
  2  FROM dual
  3  WHERE dummy = '&stupidvar';
old   1: SELECT 'print stupidvar:' || '&stupidvar'
new   1: SELECT 'print stupidvar:' || 'X'
old   3: WHERE dummy = '&stupidvar'
new   3: WHERE dummy = 'X'

'PRINTSTUPIDVAR:'
-----------------
print stupidvar:X

Elapsed: 00:00:00.00

There is an other way to store variable in SQL*Plus by using Query Column Value .

The COL [UMN] has new_value option to store value from query by field name.

SQL> COLUMN stupid_column_name new_value stupid_var noprint
SQL> SELECT dummy || '.log' AS stupid_column_name
  2  FROM dual;

Elapsed: 00:00:00.00
SQL> SPOOL &stupid_var.
SQL> SELECT '&stupid_var' FROM DUAL;
old   1: SELECT '&stupid_var' FROM DUAL
new   1: SELECT 'X.log' FROM DUAL

X.LOG
-----
X.log

Elapsed: 00:00:00.00
SQL>SPOOL OFF;

As you can see, X.log value was set into the stupid_var variable, so we can find a X.log file in the current directory has some log in it.

Answer 7

In Toad I use this works:

declare 
    num number;
begin 
    ---- use 'select into' works 
    --select 123 into num from dual;

    ---- also can use :=
    num := 123;
    dbms_output.Put_line(num);
end;

Then the value will be print to DBMS Output Window.

Reference to here and here2 .

Answer 8

Here's your answer:

DEFINE num := 1;       -- The semi-colon is needed for default values.
SELECT &num FROM dual;

Answer 9

One possible approach, if you just need to specify a parameter once and replicate it in several places, is to do something like this:

SELECT
  str_size  /* my variable usage */
  , LPAD(TRUNC(DBMS_RANDOM.VALUE * POWER(10, str_size)), str_size, '0') rand
FROM
  dual  /* or any other table, or mixed of joined tables */
  CROSS JOIN (SELECT 8 str_size FROM dual);  /* my variable declaration */

This code generates a string of 8 random digits.

Notice that I create a kind of alias named str_size that holds the constant 8 . It is cross-joined to be used more than once in the query.

Answer 10

You can use a with clause and move filter criteria from a where to a join .

It helps here: Oracle SQL alternative to using DEFINE .

with
 mytab as (select 'stupidvarcontent' as myvar from dual)
SELECT
 stupiddata
FROM
  stupidtable a 
 inner join
  mytab b
 on
  a.stupidcolumn = b.myvar
WHERE ...;

It works in Oracle 12R2.
It works for one SQL command only.
It is standard ANSI notation.
I'm using it in SQL Developer.

Answer 11

Sometimes you need to use a macro variable without asking the user to enter a value. Most often this has to be done with optional script parameters. The following code is fully functional

column 1 noprint new_value 1
select '' "1" from dual where 2!=2;
select nvl('&&1', 'VAH') "1" from dual;
column 1 clear
define 1

Similar code was somehow found in the rdbms/sql directory.