Oracle PL/SQL Error PLS-00428: 'INTO' Clause Missing in SELECT Statement

This error occurs when you use a SELECT statement within a PL/SQL stored procedure without an INTO clause. In PL/SQL, SELECT statements must include an INTO clause to store the result into a variable.

For example, here's a simple PL/SQL stored procedure that selects a number and stores it in a variable:

CREATE OR REPLACE PROCEDURE get_number
IS
    my_number NUMBER;
BEGIN
    SELECT 42 INTO my_number FROM dual;
    DBMS_OUTPUT.PUT_LINE('The number is: ' || my_number);
END;
/

In this example, the INTO clause stores the result of the SELECT statement in the my_number variable. Omitting the INTO clause will result in the 'PLS-00428: an INTO clause is expected in this SELECT statement' error.