我想有一個結果「無」每次它給了我一個空結果的時間,而不是0「無」。現在它給了我一個0爲空結果。我怎麼能有一行顯示我'沒有',而不是0爲空結果。有怎樣的行顯示我空結果
我已經試過NVL(SUM(就讀), '無')AS登記並不起作用
SELECT DISTINCT lt.STUDENT_ID,lt.FIRST_NAME, lt.LAST_NAME, NVL(SUM(ENROLLED),'none') AS ENROLLED
FROM STUDENT lt
LEFT OUTER JOIN
(SELECT s.STUDENT_ID, e.ENROLL_DATE,COUNT(z.COURSE_NO) AS ENROLLED
FROM STUDENT s
LEFT JOIN ENROLLMENT e ON s.STUDENT_ID = e.STUDENT_ID
LEFT JOIN SECTION z ON e.SECTION_ID = z.SECTION_ID
WHERE s.PHONE LIKE '702%'
GROUP BY s.STUDENT_ID, e.ENROLL_DATE) rt
ON lt.STUDENT_ID = rt.STUDENT_ID
WHERE lt.PHONE LIKE '702%'
GROUP BY lt.STUDENT_ID,lt.FIRST_NAME, lt.LAST_NAME,ENROLLMENTS;
現在我得到
STUDENT_ID FIRST_NAME LAST_NAME ENROLLED
---------- ------------------------- ------------------------- -----------
253 Walter Boremmann 1
396 James E. Norman 0
etc
但我想
STUDENT_ID FIRST_NAME LAST_NAME ENROLLED
---------- ------------------------- ------------------------- -----------
253 Walter Boremmann 1
396 James E. Norman none
這通常是你會在你的表示層處理,即顯示數據的應用程序。儘管你可以嘗試'CAST'到一個varchar類型。 – CompuChip
嘗試'IF(SUM(就讀)= 0, '無',SUM(就讀))作爲enrolled'代替 – user2577405
我沒有看到你的榜樣任何空值:/ –