Oracle 11g Release 2

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CREATE TABLE APPLIES(
anumber     NUMBER(6)   NOT NULL,  /* applicant number */
pnumber     NUMBER(8)   NOT NULL, /* position number */
appDate     DATE        NOT NULL, /* application date*/
CONSTRAINT APPLIES_pkey PRIMARY KEY(anumber, pnumber)
);
    CREATE OR REPLACE TRIGGER APPLIES_AIU
      AFTER INSERT OR UPDATE ON APPLIES
    BEGIN
      FOR aRow IN (SELECT ANUMBER,
                          TRUNC(APPDATE) AS APPDATE,
                          COUNT(*) AS APPLICATION_COUNT
                     FROM APPLIES
                     GROUP BY ANUMBER, TRUNC(APPDATE)
                     HAVING COUNT(*) > 2)
      LOOP
        -- If we get to here it means we have at least one user who has applied
        -- for more than two jobs in a single day.

        RAISE_APPLICATION_ERROR(-20002, 'Applicant ' || aRow.ANUMBER ||
                                        ' applied for ' || aRow.APPLICATION_COUNT ||
                                        ' jobs on ' ||
                                        TO_CHAR(aRow.APPDATE, 'DD-MON-YYYY'));
      END LOOP;
    END APPLIES_AIU;
    /
    
    CREATE INDEX APPLIES_BIU_INDEX
      ON APPLIES(ANUMBER, TRUNC(APPDATE));
      
INSERT INTO APPLIES (ANUMBER, PNUMBER, APPDATE) VALUES (1, 100, SYSDATE);
1 rows affected

INSERT INTO APPLIES (ANUMBER, PNUMBER, APPDATE) VALUES (1, 200, SYSDATE);
1 rows affected

INSERT INTO APPLIES (ANUMBER, PNUMBER, APPDATE) VALUES (1, 300, SYSDATE);
ORA-20002: Applicant 1 applied for 3 jobs on 16-MAY-2021
ORA-06512: at "FIDDLE_NJIIPZTKCMOSZYILDCEG.APPLIES_AIU", line 12
ORA-04088: error during execution of trigger 'FIDDLE_NJIIPZTKCMOSZYILDCEG.APPLIES_AIU'