MySQL查询解析错误

Question

$week_leave = mysql_query("select count(id),leave.id from `leave`, `users` where leave.backgroundColor = 'Green' and leave.id=(select U_id from `users` where users.username='$_SESSION['username']')");

给出以下错误：

Parse error: syntax error, unexpected '' (T_ENCAPSED_AND_WHITESPACE), expecting identifier (T_STRING) or variable (T_VARIABLE) or number (T_NUM_STRING) 

我知道问题在于子查询。有什么建议吗？

Answer 1

尝试一下，您必须在大括号之间设置数据，{$_SESSION['username']}

$week_leave = mysql_query("select count(id),leave.id from `leave`, `users` where leave.backgroundColor = 'Green' and leave.id=(select U_id from `users` where users.username='{$_SESSION['username']}')");

Answer 2

您可以使用下面的答案，因为问题在于$_SESSION变量。

$week_leave = mysql_query("select count(id),leave.id from `leave`, `users` where leave.backgroundColor = 'Green' and leave.id=(select U_id from `users` where users.username='".$_SESSION['username']."')");

Answer 3

错误在这里：

$_SESSION['username']

这两个单引号与外面的另外两个单引号有冲突。您可以使用@Osama，也可以将此值赋值给如下变量：

$username = $_SESSION['username'];

然后在查询中使用'$username'