問題是在1995年和1996年有多少次採訪。您必須使用IN關鍵字進行比較。還有一個名爲YEAR()的函數,它將返回日期的年份部分。如何限制/刪除一些符合條件的記錄? (正確的語法)
表:
mysql> SELECT interviewdate "Date"
-> FROM interview;
+------------+
| Date |
+------------+
| 1995-06-01 |
| 1995-06-01 |
| 1995-06-30 |
| 1995-06-30 |
| 1995-07-01 |
| 1995-08-01 |
| 1995-08-01 |
| 1995-08-02 |
| 1995-12-01 |
| 1995-12-02 |
| 1995-12-04 |
| 1996-01-21 |
| 1996-02-01 |
| 1996-02-02 |
| 1996-07-01 |
| 1996-07-01 |
| 1996-08-01 |
| 1996-08-08 |
| 1996-08-11 |
| 1997-01-01 |
| 1997-01-01 |
| 1997-01-31 |
| 1997-02-01 |
| 1997-03-24 |
| 1997-03-31 |
| 1997-04-20 |
| 1997-04-22 |
| 1997-05-01 |
+------------+
28 rows in set (0.00 sec)
OUTPUT:
的條件是隻算那些1995年和1996年的日期到一個新的表作爲 「COUNT(*)」。有誰知道如何做到這一點?我是mySQL的新手,並試圖理解語法。我想是這樣的:
SELECT interviewdate, COUNT(interviewdate) AS "COUNT(*)"
FROM interview
GROUP BY interviewdate
HAVING COUNT(interviewdate) == 1995 AND 1996;
+----------+
| COUNT(*) |
+----------+
| 19 |
+----------+
1 row in set (0.00 sec)
當我看它時,它總是有意義的。像魅力一樣工作,謝謝! – TheAmazingKnight
@TheAmazingKnight - np,很高興它有幫助。乾杯! – user2480596