Using a substitution variable to pull data from a table

Question

Hello,
I am working with a simple program that asks the user to enter any info that will relate to a table in the db.
Thus far I have read 1,000 ways to accomplish this, and none of them work.
PROMPT
ACCEPT var PROMPT 'Enter var'
DECLARE
BEGIN
SELECT &var
FROM &table
WHERE var=tablevar;
END;

Answer 1

Thanks for the feedback. Though I understand your logic, it doesn't seem to properly apply here. This is a more detailed explanation of what I've done.
First, I create the table
CREATE TABLE starbright
(planet_num VARCHAR2(3),
planet VARCHAR2(20));
INSERT INTO starbright VALUES
(257, 'Neptune');
INSERT INTO starbright VALUES
(367, 'Venus');
INSERT INTO starbright VALUES
(586, 'Mars');
INSERT INTO starbright VALUES
(725, 'Earth');Now, with that table created, I want to be able to periodically use PL/SQL to call data from the table, such as below
DECLARE
p_no := '&planet_num';
BEGIN
INSERT p_no
INTO starbright;
SELECT planet_num
INTO p_no
FROM starbright
WHERE planet_num := p_no;
dbms_output.put_line( 'Result: ' || planet );
END;This is my generic error
Error report:
ORA-06550: line 2, column 6:
PLS-00103: Encountered the symbol "=" when expecting one of the following:
   constant exception <an identifier>
   <a double-quoted delimited-identifier> table LONG_ double ref
   char time timestamp interval date binary national character
   nchar
The symbol "<an identifier>" was substituted for "=" to continue.
ORA-06550: line 6, column 8:
PLS-00103: Encountered the symbol "P_NO" when expecting one of the following:
   into <a SQL statement>
ORA-06550: line 11, column 18:
PLS-00103: Encountered the symbol "=" when expecting one of the following:
   . ( * @ % & = - + ; < / > at for in is mod remainder not rem
   <an exponent (**)> <> or != or ~= >= <= <> and or like LIKE2_
   LIKE4_ LIKEC_ between group h
06550. 00000 -  "line %s, column %s:\n%s"
*Cause:    Usually a PL/SQL compilation error.
*Action: