How can I read input values written by a user? In PL/SQL-CodePudding

DECLARE
  text VARCHAR2(20) := &text;
BEGIN
  DBMS_OUTPUT.PUT_LINE(text);
END;

When I declare this anonymous block so that the user enters a value by keyboard, it shows me an error in the console output.

This is the error:

Error starting at line: 3 of the command:
 DECLARE
  text VARCHAR2(20) := Hello;
 START
  DBMS_OUTPUT.PUT_LINE(text);
  END;
Bug report -
ORA-06550: line 2, column 26:
PLS-00201: identifier 'HELLO' must be declared
ORA-06550: line 2, column 10:
PL/SQL: Item ignored
ORA-06550: line 4, column 25:
PLS-00320: The type declaration of this expression is incomplete or has a wrong format.
incorrect
ORA-06550: line 4, column 4:
PL/SQL: Statement ignored
06550. 00000 - "line %s, column %s:\n%s"
*Cause: Usually a PL/SQL compilation error.
*Action:

CodePudding user response：

As this is a substitution variable whose datatype is varchar2, enclose it into single quotes (as any other string):

SQL> declare
  2    text varchar2(20) := '&text';            --> this
  3  begin
  4    dbms_output.put_line(text);
  5  end;
  6  /
Enter value for text: Hello
old   2:   text varchar2(20) := '&text';
new   2:   text varchar2(20) := 'Hello';
Hello

PL/SQL procedure successfully completed.

SQL>

CodePudding user response：

In this block, you are trying to pass another variable Hello (not its value) to the text variable. Use apostrophes to make the compiler interpret it as a value and not as a variable - 'Hello'

DECLARE
  text VARCHAR2(20) := Hello; --<< change to 'Hello'
 START
  DBMS_OUTPUT.PUT_LINE(text);
 END;