UPDATE语句结合REPLACE函数进行字符串替换。UPDATE语句结合REPLACE函数进行字符串替换。php，$sql = "SELECT * FROM users WHERE age > 18";，$result = $conn>query($sql);，`，，这段代码会从users`表中筛选出年龄大于18岁的用户。SELECT @@GLOBAL.hostname;。php，$query = "SELECT * FROM table WHERE condition1 AND condition2";，$result = $conn>query($query);，while ($row = $result>fetch_assoc()) {， // process row，}，``GROUP BY子句和HAVING子句。假设你有一个名为users的表，并且你想查找在email列中重复的数据，你可以使用以下查询：，，``sql，SELECT email, COUNT(*)，FROM users，GROUP BY email，HAVING COUNT(*) > 1;，`，，这个查询会返回所有在email`列中出现超过一次的记录及其出现的次数。Powered By Z-BlogPHP 1.7.3
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