如何声明变量并在同一个Oracle SQL脚本中使用它？

Question

我想编写可重用的代码,需要在开头声明一些变量并在脚本中重用它们,例如:

DEFINE stupidvar = 'stupidvarcontent';

SELECT stupiddata
FROM stupidtable
WHERE stupidcolumn = &stupidvar;

如何声明一个变量并在后面的语句中重用它,比如使用SQLDeveloper.

---

尝试

• 使用DECLARE部分和插入下面的SELECT语句BEGIN和END;.使用获取变量&stupidvar.
• 使用关键字DEFINE并访问变量.
• 使用关键字VARIABLE并访问变量.

但我在尝试期间遇到各种错误(未绑定变量,语法错误,预期SELECT INTO...).

Answer 1

在SQL*Plus脚本中有几种声明变量的方法.

首先是使用VAR.为VAR分配值的机制是使用EXEC调用:

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>

当我们想要调用具有OUT参数或函数的存储过程时,VAR特别有用.

Alternativley我们可以使用替换变量.这些适用于交互模式:

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>

当我们编写一个调用其他脚本的脚本时,预先定义变量会很有用:

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>

最后是匿名的PL/SQL块.如您所见,我们仍然可以交互地为声明的变量赋值:

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

如果它是char变量,请尝试使用双引号:

DEFINE stupidvar = "'stupidvarcontent'";

要么

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

在PL/SQL v.10中

keyword declare用于声明变量

DECLARE stupidvar varchar(20);

指定一个值,您可以在声明时设置它

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

或者在你使用INTO语句的变量中选择一些东西,但是你需要将语句包装在中,BEGIN并且END还需要确保只返回单个值,并且不要忘记分号.

所以完整的声明如下:

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

您的变量仅在其中可用BEGIN,END因此如果您想要使用多个变量,则必须进行多次BEGIN END包装

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;

希望这能为您节省一些时间

Answer 4

如果要声明日期，然后在SQL Developer中使用它。

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

SELECT * 
FROM proposal 
WHERE prop_start_dt = &PROPp_START_DT

Answer 5

只想添加Matas的答案。也许很明显，但是我搜索了很长时间才发现该变量只能在BEGIN-END构造内部访问，因此如果您以后需要在某些代码中使用它，则需要将此代码放在BEGIN内部-END 块。

请注意，这些块可以嵌套：

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

问题是在脚本中使用变量对我来说意味着它将在 SQL*Plus 中使用。

问题是您错过了引号，Oracle 无法将值解析为数字。

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

由于自动类型转换（或任何名称），此示例工作正常。

如果通过在 SQL*Plus 中键入 DEFINE 来检查，它将显示 num 变量是 CHAR。

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

在这种情况下这不是问题，因为 Oracle 可以处理将字符串解析为数字（如果它是有效数字）。

当字符串无法解析为数字时，Oracle 无法处理它。

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

带引号，所以不要强迫 Oracle 解析为数字，就可以了：

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

因此，要回答原始问题，应该像这个示例一样：

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

还有另一种方法可以使用Query Column Value在 SQL*Plus 中存储变量。

在COL [UMN]有NEW_VALUE从查询的字段名选项储存价值。

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;

如您所见，X.log 值被设置到了愚蠢的变量变量中，因此我们可以在当前目录中找到一个 X.log 文件，其中有一些日志。

Answer 7

在蟾蜍中我使用这个作品：

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;

然后该值将被打印到DBMS Output窗口。

参考这里和这里2。