Question

我尝试SELECT来自此数据库WHERE statement_from或username = = $username但是这不是{\ n}}工作正常。我已经查看了之前提出的类似问题，但不确定如何在此查询中实现先前的答案。

   "SELECT * FROM `usr_statements` WHERE `statement_from` = '$username' 
    OR `username` = '$username' AND `statement_timestamp` > '$start_date'
    AND `statement_timestamp` < '$end_date' ORDER BY `statement_ref` DESC"

我想要实现的是选择数据库中statement_from或username = = $username的所有结果。

Answer 1

目前您的查询已经过验证，如此

WHERE `statement_from` = '$username' 
    OR (`username` = '$username' AND `statement_timestamp` > '$start_date')
    AND `statement_timestamp` < '$end_date'

因为AND的高于<{em> 优先级高于OR所以AND将首先评估。

您需要添加正确的括号

SELECT * FROM `usr_statements` 
WHERE (`statement_from` = '$username' 
    OR `username` = '$username') 
   AND `statement_timestamp` > '$start_date'
   AND `statement_timestamp` < '$end_date' 
ORDER BY `statement_ref` DESC

此外，您可以使用IN运算符执行 Jarlh 在评论中提到的

SELECT * FROM `usr_statements` 
WHERE $username in (statement_from, username)
   AND `statement_timestamp` > '$start_date'
   AND `statement_timestamp` < '$end_date' 
ORDER BY `statement_ref` DESC

Answer 2

运营商的优先级为NOT - ＆gt; AND - ＆gt; OR，所以你需要一些药物治疗：

"SELECT * FROM `usr_statements` WHERE (`statement_from` = '$username' 
    OR `username` = '$username') AND `statement_timestamp` > '$start_date'
    AND `statement_timestamp` < '$end_date' ORDER BY `statement_ref` DESC"

SQL WHERE，OR和AND

2 个答案: