要从通话记录中查找A用户通话过的所有人,可以使用SQL查询。假设你的通话记录表结构如下:
CALL_LOGS ( id INT PRIMARY KEY, caller VARCHAR(255), receiver VARCHAR(255), call_time DATETIME )
这里有一个SQL查询示例,用于查找用户A通话过的所有人(无论是作为主叫还是被叫):
SELECT DISTINCT other_user FROM ( SELECT receiver AS other_user FROM CALL_LOGS WHERE caller = 'A' UNION SELECT caller AS other_user FROM CALL_LOGS WHERE receiver = 'A' ) AS combined_calls;解释:
内层子查询:将两次选择结果联合在一起,第一次选择是找出A用户作为主叫拨打电话的所有被叫用户,第二次选择是找出A用户作为被叫接听电话的所有主叫用户。
SELECT receiver AS other_user FROM CALL_LOGS WHERE caller = 'A' UNION SELECT caller AS other_user FROM CALL_LOGS WHERE receiver = 'A'SELECT receiver AS other_user FROM CALL_LOGS WHERE caller = 'A':查找A用户作为主叫的所有被叫用户。UNION:将两个结果集进行合并,去除重复值。SELECT caller AS other_user FROM CALL_LOGS WHERE receiver = 'A':查找A用户作为被叫的所有主叫用户。
外层查询:选择出所有的不同用户。sqlSELECT DISTINCT other_userFROM ( ...) AS combined_calls;
使用DISTINCT确保结果中没有重复的用户。这样,你就可以查找到用户A通话过的所有人。
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