推測你可能是要求"當日同月份銷售量總和".
<pre class="c" name="code">CREATE TABLE ithelp150317(
id TINYINT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY,
amount DECIMAL(7,2) NOT NULL,
trade_dt DATE NOT NULL
);
INSERT INTO ithelp150317(amount, trade_dt) VALUES
(200.3, "2015-02-20"),
(450.2, "2015-02-21"),
(107.5, "2015-03-10"),
(264.2, "2015-02-11"),
(2227.5, "2015-03-12");
SELECT MONTH(NOW()) AS "月份"
, SUM(amount) AS "當月目前交易總額"
FROM ithelp150317
WHERE MONTH(trade_dt) = MONTH(NOW());
+--------+--------------------------+
| 月份 | 當月目前交易總額 |
+--------+--------------------------+
| 3 | 2335.00 |
+--------+--------------------------+
PL/SQL
<pre class="c" name="code">SELECT * FROM a
WHERE SYSDATE = TO_DATE(a.date, 'YYYYMMDD')