具有重复表名的 SELECT 语句

Question

我有两个不同的功能 sql 语句需要组合。

尽量避免在 SELECT 语句中出现重复名称，同时仍在 SQL 查询中检索我要查找的数据。

第一个更长的查询：

Select USER.USER_NAME, ASSET.NAME AS KACE_ASSET_NAME, FIELD_31, V3.FIELD_VALUE AS CUSTOM_3, FIELD_20 AS BARCODE, FIELD_27 AS SERIAL_NUMBER

FROM ASSET
JOIN USER ON ASSET.OWNER_ID = USER.ID

JOIN ASSET_DATA_5 ON ASSET.ASSET_DATA_ID = ASSET_DATA_5.ID AND ASSET_TYPE_ID = 5


LEFT JOIN USER_FIELD_VALUE V3 ON V3.USER_ID = USER.ID AND V3.FIELD_ID = 3 

LEFT JOIN ASSET ASSET_LOCATION  ON ASSET_LOCATION.ID = ASSET.LOCATION_ID
LEFT JOIN ASSET_ASSOCIATION J21 ON J21.ASSET_ID = ASSET.ID AND J21.ASSET_FIELD_ID=21
LEFT JOIN ASSET A21 ON A21.ID = J21.ASSOCIATED_ASSET_ID
LEFT JOIN ASSET_DATA_1 AD21 ON AD21.ID = A21.ASSET_DATA_ID
WHERE V3.FIELD_VALUE = 'TERMINATED'

第二个较小的查询：

SELECT ASSET.NAME AS CITY 
FROM ASSET_DATA_1 LEFT JOIN ASSET ON ASSET_DATA_1.ID = ASSET.ASSET_DATA_ID AND ASSET.ASSET_TYPE_ID=1

我尽力将两者结合起来：

Select USER.USER_NAME, ASSET.NAME AS KACE_ASSET_NAME, FIELD_31, V3.FIELD_VALUE AS CUSTOM_3, FIELD_20 AS BARCODE, FIELD_27 AS SERIAL_NUMBER, ASSET.NAME as CITY

FROM ASSET
JOIN USER ON ASSET.OWNER_ID = USER.ID

JOIN ASSET_DATA_5 ON ASSET.ASSET_DATA_ID = ASSET_DATA_5.ID AND ASSET_TYPE_ID = 5


LEFT JOIN USER_FIELD_VALUE V3 ON V3.USER_ID = USER.ID AND V3.FIELD_ID = 3 

LEFT JOIN ASSET ASSET_LOCATION  ON ASSET_LOCATION.ID = ASSET.LOCATION_ID
LEFT JOIN ASSET_ASSOCIATION J21 ON J21.ASSET_ID = ASSET.ID AND J21.ASSET_FIELD_ID=21
LEFT JOIN ASSET A21 ON A21.ID = J21.ASSOCIATED_ASSET_ID
LEFT JOIN ASSET_DATA_1 AD21 ON AD21.ID = A21.ASSET_DATA_ID


#IMPORTANT JOIN HERE - NEED TO LINK THIS INFO BACK TO SELECT STATEMENT
LEFT JOIN ASSET ASSET_DATA_1 ON ASSET_DATA_1.ID = ASSET.ASSET_DATA_ID AND ASSET.ASSET_TYPE_ID=1  


WHERE V3.FIELD_VALUE = 'TERMINATED'

因此尝试构建此 SELECT 语句，以便将 assets.name 正确链接回此处列出的最后一个 LEFT JOIN。问题是有两个名为 ASSET.NAME 的列和两个 ASSET 表，我相信。我不确定如何在 SELECT 语句中调用“ASSET_DATA_1”表中的“ASSET.NAME”数据，而不仅仅是获取第一个 Asset 表的副本。 我四处寻找答案，并尝试了诸如括号中的 SELECT 语句和 UNION 命令之类的方法，但这些似乎都不是答案。 SQL noob 并对此感到有些不知所措。

Answer 1

要删除重复项，请对所有选定的列使用 group by。

SELECT USER.USER_NAME, ASSET.NAME AS KACE_ASSET_NAME, FIELD_31, V3.FIELD_VALUE AS CUSTOM_3, FIELD_20 AS BARCODE, FIELD_27 AS SERIAL_NUMBER
FROM ASSET
JOIN USER ON ASSET.OWNER_ID = USER.ID
JOIN ASSET_DATA_5 ON ASSET.ASSET_DATA_ID = ASSET_DATA_5.ID AND ASSET_TYPE_ID = 5
LEFT JOIN USER_FIELD_VALUE V3 ON V3.USER_ID = USER.ID AND V3.FIELD_ID = 3 
LEFT JOIN ASSET ASSET_LOCATION  ON ASSET_LOCATION.ID = ASSET.LOCATION_ID
LEFT JOIN ASSET_ASSOCIATION J21 ON J21.ASSET_ID = ASSET.ID AND J21.ASSET_FIELD_ID=21
LEFT JOIN ASSET A21 ON A21.ID = J21.ASSOCIATED_ASSET_ID
LEFT JOIN ASSET_DATA_1 AD21 ON AD21.ID = A21.ASSET_DATA_ID
WHERE V3.FIELD_VALUE = 'TERMINATED'
GROUP BY USER.USER_NAME, ASSET.NAME, FIELD_31, V3.FIELD_VALUE, FIELD_20, FIELD_27;

Answer 2

如果你想删除重复的行，你应该使用 DISTINCT 子句

Select DISTINCT 

    USER.USER_NAME, ASSET.NAME AS KACE_ASSET_NAME, FIELD_31,
     V3.FIELD_VALUE AS CUSTOM_3, FIELD_20 AS BARCODE, FIELD_27 AS SERIAL_NUMBER

FROM ASSET
JOIN USER ON ASSET.OWNER_ID = USER.ID

JOIN ASSET_DATA_5 ON ASSET.ASSET_DATA_ID = ASSET_DATA_5.ID AND ASSET_TYPE_ID = 5


LEFT JOIN USER_FIELD_VALUE V3 ON V3.USER_ID = USER.ID AND V3.FIELD_ID = 3 

LEFT JOIN ASSET ASSET_LOCATION  ON ASSET_LOCATION.ID = ASSET.LOCATION_ID
LEFT JOIN ASSET_ASSOCIATION J21 ON J21.ASSET_ID = ASSET.ID AND J21.ASSET_FIELD_ID=21
LEFT JOIN ASSET A21 ON A21.ID = J21.ASSOCIATED_ASSET_ID
LEFT JOIN ASSET_DATA_1 AD21 ON AD21.ID = A21.ASSET_DATA_ID
WHERE V3.FIELD_VALUE = 'TERMINATED'

（当你没有聚合函数时，在这个范围内使用 group by 在 sql 中已被弃用，并且在最新版本的 mysql 中是不允许的）

Answer 3

您可以为资产表的第二个副本添加不同的别名：

Select USER.USER_NAME, 
ASSET.NAME AS KACE_ASSET_NAME, 
FIELD_31, 
V3.FIELD_VALUE AS CUSTOM_3, 
FIELD_20 AS BARCODE, 
FIELD_27 AS SERIAL_NUMBER,
 asset_again .NAME as CITY

FROM ASSET
JOIN USER ON ASSET.OWNER_ID = USER.ID

JOIN ASSET_DATA_5 ON ASSET.ASSET_DATA_ID = ASSET_DATA_5.ID AND ASSET_TYPE_ID = 5


LEFT JOIN USER_FIELD_VALUE V3 ON V3.USER_ID = USER.ID AND V3.FIELD_ID = 3 

LEFT JOIN ASSET ASSET_LOCATION  ON ASSET_LOCATION.ID = ASSET.LOCATION_ID
LEFT JOIN ASSET_ASSOCIATION J21 ON J21.ASSET_ID = ASSET.ID AND J21.ASSET_FIELD_ID=21
LEFT JOIN ASSET A21 ON A21.ID = J21.ASSOCIATED_ASSET_ID
LEFT JOIN ASSET_DATA_1 AD21 ON AD21.ID = A21.ASSET_DATA_ID


#IMPORTANT JOIN HERE - NEED TO LINK THIS INFO BACK TO SELECT STATEMENT
LEFT JOIN ASSET asset_again ON ad21 .ID = asset_again.ASSET_DATA_ID AND asset_again .ASSET_TYPE_ID=1  


WHERE V3.FIELD_VALUE = 'TERMINATED'

事实上，再次阅读这个问题，我看到你试图通过使用 ASSET_DATA_1 作为别名来混淆事情。使用唯一的（查询）别名并使用该别名来引用列列表中的表