Sql 检查触发器中的未来日期

如果用户试图用未来日期替换当前日期，我想启动触发器。但触发器中可能不允许使用子查询。我如何解决这个问题？任何建议

  CREATE OR REPLACE TRIGGER check_join_date
        BEFORE UPDATE OF join_date ON DOCTOR
        FOR EACH ROW
        WHEN (NEW.join_date > (SELECT CURRENT_DATE+1 FROM DUAL) )
    BEGIN
        RAISE_APPLICATION_ERROR(-20509,'Do not Enter Future Date..');
    END check_join_date;
    /

我在Oracle中运行此代码后出现此错误

ORA-02251: subquery not allowed here

测试这个

CREATE OR REPLACE TRIGGER check_join_date
        BEFORE UPDATE OF join_date ON DOCTOR
        FOR EACH ROW
        WHEN (NEW.join_date > CURRENT_DATE+1)
    BEGIN
        RAISE_APPLICATION_ERROR(-20509,'Do not Enter Future Date..');
    END check_join_date;
    /

测试这个

CREATE OR REPLACE TRIGGER check_join_date
        BEFORE UPDATE OF join_date ON DOCTOR
        FOR EACH ROW
        WHEN (NEW.join_date > CURRENT_DATE+1)
    BEGIN
        RAISE_APPLICATION_ERROR(-20509,'Do not Enter Future Date..');
    END check_join_date;
    /