Question

我正在运行查询

SELECT LOCATION_OID,UPPER(NAME) AS LOCATION_NAME FROM LOCATION LEFT OUTER JOIN LOCATION_CHILD_LOCATION parent on (parent.LOCATION_OID = LOCATION.LOCATION_OID)

有两个表LOCATION和LOCATION_CHILD_LOCATION，Location有456条记录，location_child_location有4条记录。 location_child_location中的记录使用来自父节点位置表的location_oid进行映射。为什么这个查询会出错？

Answer 1

您需要指定您想要LOCATION_OID的表格，否则分析器会混淆它必须查找哪个表来获取数据。试试这个：

SELECT LOCATION.LOCATION_OID,UPPER(NAME) AS LOCATION_NAME 
FROM LOCATION LEFT OUTER JOIN LOCATION_CHILD_LOCATION parent
 on (parent.LOCATION_OID = LOCATION.LOCATION_OID)

Answer 2

您必须在LOCATION_OID子句中的select前添加表名：

SELECT LOCATION.LOCATION_OID,UPPER(NAME) AS LOCATION_NAME FROM LOCATION LEFT OUTER JOIN LOCATION_CHILD_LOCATION on (parent.LOCATION_OID = LOCATION.LOCATION_OID)

Answer 3

请尝试以下查询，其中正确提及命名以避免表格中的冲突：

SELECT l.LOCATION_OID,UPPER(NAME) AS LOCATION_NAME 
FROM LOCATION as l
LEFT OUTER JOIN LOCATION_CHILD_LOCATION parent on (parent.LOCATION_OID = LOCATION.LOCATION_OID)

Answer 4

为每个表使用别名，而不是混合两种方法（使用和不使用别名）：

SELECT L.LOCATION_OID
    ,UPPER(L.NAME) AS LOCATION_NAME
FROM LOCATION L
LEFT OUTER JOIN LOCATION_CHILD_LOCATION P ON P.LOCATION_OID = L.LOCATION_OID

希望这会有所帮助。

查询抛出错误; “各列定义不明”

4 个答案: