String data types, such as VARCHAR2 or NVARCHAR2 require a size constraint. Omitting the size results in the exception
PLS-00215: String length constraints must be in range (1 .. 32767) being raised.
Noncompliant code example
DECLARE
foo VARCHAR2; -- Noncompliant - raises PLS-00215
BEGIN
NULL;
END;
/
Compliant solution
DECLARE
foo VARCHAR2(42); -- Compliant
BEGIN
NULL;
END;
/
