我有2個表,我使用連接從這兩個表中獲取通用記錄。SQL查詢記錄加倍左加入
我已經使用了下面的查詢,但我的問題是我得到的記錄加倍。
查詢如下,你能幫我嗎?
查詢#1:(正確的輸出)
mysql> SELECT DISTINCT
xId1 AS xId1,
xArea AS xArea,
YEAR (
STR_TO_DATE(
`xDate`,
'%d/%m/%Y'
)
) AS xYear
FROM
doTable1 AA
LEFT JOIN doTable2 BB ON AA.xId1 = BB.xId2
WHERE
xArea IN ('XX1A')
AND YEAR (
STR_TO_DATE(
`xDate`,
'%d/%m/%Y'
)
) = 2016;
+-----------+-------+-------+
| xId | xArea | xYear |
+-----------+-------+-------+
| 91623545 | XX1A | 2016 |
| 89748942 | XX1A | 2016 |
| 115956872 | XX1A | 2016 |
| 103595808 | XX1A | 2016 |
| 103623873 | XX1A | 2016 |
| 103623892 | XX1A | 2016 |
| 103623872 | XX1A | 2016 |
| 103623894 | XX1A | 2016 |
| 112072738 | XX1A | 2016 |
| 112072751 | XX1A | 2016 |
| 117818773 | XX1A | 2016 |
| 117818753 | XX1A | 2016 |
| 117885105 | XX1A | 2016 |
| 117960040 | XX1A | 2016 |
| 117885111 | XX1A | 2016 |
+-----------+-------+-------+
15 rows in set
查詢#2:(不正確的輸出,因爲2016年我有18個記錄 - 加倍的存在 - 而不是15條作爲查詢#1):
mysql> SELECT
DISTINCT COUNT(*) AS xQQQ,
xArea AS xArea,
YEAR (
STR_TO_DATE(
xDate,
'%d/%m/%Y'
)
) AS xYear
FROM
doTable1 AA
LEFT JOIN doTable2 BB ON AA.xId1 = BB.xId2
WHERE xArea IN ('XX1A')
GROUP BY
xArea,
xYear;
+------+-------+-------+
| xQQQ | xArea | xYear |
+------+-------+-------+
| 4 | XX1A | 2014 |
| 49 | XX1A | 2015 |
| 18 | XX1A | 2016 |
+------+-------+-------+
3 rows in set
在這些情況下,我將SELECT替換爲SELECT *,然後運行沒有GROUP BY的查詢,並查看每行。沒有完整的數據庫,幾乎不可能猜出問題所在。 – Linkan
@Linkan謝謝yuo的幫助,但是我發佈了**查詢#1 **,沒有** GROUP BY ** –
那str_to_date位似乎有點多餘 – Strawberry