sql - SQL。如何映射两列频率？

我有这个PROJECT表：

    PJNO  TASKNO        DESCRIP                     Other...
    5555    11        Prototype New Screens
    4444    21        Test First Prototype
    5555    13        Create Test Plan
    6666    73        Prototype Custom Screens
    7777    73        Present Test Plan
    3333    81        Install PT-Sale Package
    7777    74        Conduct Tests
    5555    12        Convert Data Files

我需要列出所有至少包含2个任务的项目。

SELECT PJNO
FROM PROJECT
WHERE // COUNT TASKNO... here I am not sure how to introduce a conditional statement?

最佳答案

SELECT PJNO
FROM PROJECT
GROUP BY PJNO
HAVING COUNT(TASKNO)>1;