如何避免在选择查询选项上重复选择？

Question

我在如何避免查询重复中遇到问题，我的代码如下：

<div class="control-group">
                                <label class="control-label" for="inputPassword">User:</label>
                                <div class="controls">
                                    <select type="text" name="user_id"  placeholder="User" >

                                        <option><?php

$sql1=mysql_query("SELECT * from `user`,`appointment` where user.user_id = appointment.user_id and appointment.branch_id = $session_branchid")or die(mysql_error);

while($row = mysql_fetch_array($sql1)){
echo "<option value=".$row["user_id"].">" .$row["firstname"].' '.$row["lastname"]. "</option>";

}
?></option>

                                    </select>
                                </div>
                            </div>

代码还可以，但用户反复选择选项？

Answer 1

您必须更改查询。

  SELECT * from `user` Join `appointment` ON ( user.user_id = appointment.user_id) where appointment.branch_id = $session_branchid

Answer 2

您可以将SQL部分更改为：

$sql1 = mysql_query("SELECT DISTINCT * from `user`,`appointment` where user.user_id = appointment.user_id and appointment.branch_id = $session_branchid")or die(mysql_error);

如果用户的数据相等，则SQL将仅返回一条记录。