[英]What is the best way to construct a complex sql query in sqlite3
我有两张桌子
用户
+----+-------+--------------+-------------------------------+ | ID | Login | Password | Guid | +----+-------+--------------+-------------------------------+ | 1 | john | johnpassword | 8f6nf7-r73hd3-43nhd7-df74hd | | 2 | mary | marypassword | 4552mf-234jdf-43njduy-fwujd | | 3 | mark | markpassword | dfh32-fdwe34-3442dr-43wdj45 | | 4 | tom | tompassword | edri84-234jd-234jf-2345jd83 | +----+-------+--------------+-------------------------------+
往来
+----+---------------+------------------+---------+ | ID | RequestSender | RequestRecipient | Status | +----+---------------+------------------+---------+ | 1 | 1 | 2 | 3 | | 2 | 1 | 3 | 3 | | 3 | 4 | 1 | 3 | +----+---------------+------------------+---------+
RequestSender和RequestRecipient是“用户”表中“ ID”的外键。 状态可以是1(已请求),2(已拒绝)和3(已接受)
我想编写一个查询,通过仅提供他的guid从联系人表中获取所有约翰的联系人,并得到这样的结果
结果
+----+-------+-----------------------------+ | ID | Login | Guid | +----+-------+-----------------------------+ | 2 | mary | 4552mf-234jdf-43njduy-fwujd | | 3 | mark | dfh32-fdwe34-3442dr-43wdj45 | | 4 | tom | edri84-234jd-234jf-2345jd83 | +----+-------+-----------------------------+
请注意,只要Status为3(即有效的联系关系),john的ID可以同时位于RequestSender或RequestRecipient上
我正在使用SQLITE3,所以无法在SQL Server上执行某些复杂的工作
根本没有复杂的东西。 这是非常基本的SQL:
SELECT ID, Login, Guid FROM Users WHERE ID IN (
SELECT RequestSender FROM Contacts WHERE RequestRecipient=(
SELECT ID FROM Users WHERE Guid=?1
) UNION SELECT RequestRecipient FROM Contacts WHERE RequestSender=(
SELECT ID FROM Users WHERE Guid=?1
)
)
只需将?1
替换为所需的GUID。
编辑:更正的表名称。
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