如何像在T-SQL中一样在PL / SQL中声明和使用变量？

In Sql Server, often times when I'm testing the body of a stored procedure, I copy the body into SSMS, DECLARE the variables at the top of the page, set them to some sample values, and execute the body as-is.

在Sql Server中，经常在我测试存储过程的主体时，我将主体复制到SSMS中，将页面顶部的变量DECLARE，将它们设置为一些样本值，然后按原样执行主体。

For Example, if my proc is

例如，如果我的proc是

CREATE PROC MySampleProc
    @Name   VARCHAR(20)
AS
    SELECT @Name

Then my test sql would be

然后我的测试SQL将是

DECLARE @Name VARCHAR(20)
SET     @Name = 'Tom'

    SELECT @Name

What is the Oracle PL/SQL equivalent to this?

什么是Oracle PL / SQL相当于此？

This is the closest that I've come up with, but I'm getting "PLS-00428: an INTO clause is expected in this SELECT statement"

这是我提出的最接近的，但是我得到了“PLS-00428：在这个SELECT语句中需要一个INTO子句”

DECLARE
   myname varchar2(20);
BEGIN
     myname := 'Tom';

     select myname from DUAL;
END;

This is a better example of what I'm really trying to do:

这是我真正想要做的更好的例子：

DECLARE
   myname varchar2(20);
BEGIN
     myname := 'Tom';

     SELECT *
     FROM   Customers
     WHERE  Name = myname;
END;

But again, it wants an 'INTO' when really I just want the records printed on the screen, not stored in another table....

但是，当我真的只想要在屏幕上打印的记录而不是存储在另一个表格中时，它想要一个'INTO'。

RESOLVED:

解决：

Thanks to @Allan, I've got it working well enough. Oracle SQL Developer apparently remembers the parameter values you supply it with. PL/SQL Developer, however, wants nothing to do with this....

感谢@Allan，我的工作得很好。 Oracle SQL Developer显然会记住您提供的参数值。但是，PL / SQL Developer不需要这个......

If you "Run As Script", it will abide by your defaults, but it will only return results as ASCI text, not in a grid/spreadsheet

如果你“运行为脚本”，它将遵守你的默认值，但它只会返回结果为ASCI文本，而不是网格/电子表格

3 个解决方案

#1

Revised Answer

修订后的答案

If you're not calling this code from another program, an option is to skip PL/SQL and do it strictly in SQL using bind variables:

如果您没有从其他程序调用此代码，则可以选择跳过PL / SQL并使用绑定变量在SQL中严格执行此操作：

var myname varchar2(20);

exec :myname := 'Tom';

SELECT *
FROM   Customers
WHERE  Name = :myname;

In many tools (such as Toad and SQL Developer), omitting the var and exec statements will cause the program to prompt you for the value.

在许多工具（例如Toad和SQL Developer）中，省略var和exec语句将导致程序提示您输入值。

---

Original Answer

原始答案

A big difference between T-SQL and PL/SQL is that Oracle doesn't let you implicitly return the result of a query. The result always has to be explicitly returned in some fashion. The simplest way is to use DBMS_OUTPUT (roughly equivalent to print) to output the variable:

T-SQL和PL / SQL之间的一个很大区别是Oracle不允许您隐式返回查询结果。结果总是必须以某种方式显式返回。最简单的方法是使用DBMS_OUTPUT（大致相当于print）来输出变量：

DECLARE
   myname varchar2(20);
BEGIN
     myname := 'Tom';

     dbms_output.print_line(myname);
END;

This isn't terribly helpful if you're trying to return a result set, however. In that case, you'll either want to return a collection or a refcursor. However, using either of those solutions would require wrapping your code in a function or procedure and running the function/procedure from something that's capable of consuming the results. A function that worked in this way might look something like this:

但是，如果您尝试返回结果集，这并不是非常有用。在这种情况下，您要么返回一个集合，要么返回一个refcursor。但是，使用这些解决方案中的任何一个都需要将代码包装在函数或过程中，并从能够消耗结果的内容中运行函数/过程。以这种方式工作的函数可能如下所示：

CREATE FUNCTION my_function (myname in varchar2)
     my_refcursor out sys_refcursor
BEGIN
     open my_refcursor for
     SELECT *
     FROM   Customers
     WHERE  Name = myname;

     return my_refcursor;
END my_function;

#2

In Oracle PL/SQL, if you are running a query that may return multiple rows, you need a cursor to iterate over the results. The simplest way is with a for loop, e.g.:

在Oracle PL / SQL中，如果您正在运行可能返回多行的查询，则需要一个游标来迭代结果。最简单的方法是使用for循环，例如：

declare
  myname varchar2(20) := 'tom';
begin
  for result_cursor in (select * from mytable where first_name = myname) loop
    dbms_output.put_line(result_cursor.first_name);
    dbms_output.put_line(result_cursor.other_field);
  end loop;
end;

If you have a query that returns exactly one row, then you can use the select...into... syntax, e.g.:

如果您的查询只返回一行，那么您可以使用select ... into ...语法，例如：

declare 
  myname varchar2(20);
begin
  select first_name into myname 
    from mytable 
    where person_id = 123;
end;

#3

Variables are not defined, but declared.

变量未定义，但已声明。

This is possible duplicate of declare variables in a pl/sql block

这可能是pl / sql块中声明变量的重复

But you can look here :

但你可以看看这里：

http://docs.oracle.com/cd/B19306_01/appdev.102/b14261/fundamentals.htm#i27306

http://docs.oracle.com/cd/B19306_01/appdev.102/b14261/fundamentals.htm#i27306

http://docs.oracle.com/cd/B19306_01/appdev.102/b14261/overview.htm

http://docs.oracle.com/cd/B19306_01/appdev.102/b14261/overview.htm

UPDATE:

更新：

Refer here : How to return a resultset / cursor from a Oracle PL/SQL anonymous block that executes Dynamic SQL?

请参阅此处：如何从执行动态SQL的Oracle PL / SQL匿名块返回结果集/游标？