將多個計數返回到一個查詢中

Question

我試圖將計數值返回到多列（ORDERS_1990，ORDERS_1991）中，但是我收到錯誤“缺少關鍵字”。

SELECT
 (SELECT COUNT(*) FROM ORDERS WHERE (ODATE BETWEEN '01-JAN-90' AND '31-DEC-90')),
 (SELECT COUNT(*) FROM ORDERS WHERE (ODATE BETWEEN '01-JAN-91' AND '31-DEC-91'))
INTO ORDERS_1990, ORDERS_1991
FROM ORDERS;

Answer 1

您最有可能收到該消息，因為您在PLSQL塊之外使用SELECT ... INTO ... 如果只想標記結果，則只需正常命名子查詢即可；

SELECT
 (SELECT COUNT(*) FROM ORDERS 
  WHERE (ODATE BETWEEN '01-JAN-90' AND '31-DEC-90')) ORDERS_1990,
 (SELECT COUNT(*) FROM ORDERS 
  WHERE (ODATE BETWEEN '01-JAN-91' AND '31-DEC-91')) ORDERS_1991
FROM DUAL;

Answer 2

您可以使用條件聚合：

SELECT SUM(CASE WHEN ODATE BETWEEN '01-JAN-90' AND '31-DEC-90' THEN 1 ELSE 0 END),
       SUM(CASE WHEN ODATE BETWEEN '01-JAN-91' AND '31-DEC-91' THEN 1 ELSE 0 END)
INTO ORDERS_1991, ORDERS_1992
FROM ORDERS;

我不確定為什么會收到“缺少關鍵字”錯誤。 我希望錯誤是您返回太多行。 我認為以下方法應該有效（假設您位於PL / SQL塊中）：

SELECT (SELECT COUNT(*) FROM ORDERS WHERE (ODATE BETWEEN '01-JAN-90' AND '31-DEC-90')),
       (SELECT COUNT(*) FROM ORDERS WHERE (ODATE BETWEEN '01-JAN-91' AND '31-DEC-91'))
INTO ORDERS_1990, ORDERS_1991
FROM dual;