Php SQL语法错误 $query=“从来宾位置选择*”； 如果（$_POST['include2']==“是”）{ $guestNameLast=isset（$_POST['guestNameLast']）？$_POST['guestNameLast']：''； $query.=“guestNameLast类似“%$guestNameLast%””； $msg.=“guest that”。$guestNameLast.；

您的SQL语法有错误；请查看与MySQL服务器版本对应的手册，以了解第1行“guestNameLast LIKE”%%附近使用的语法是否正确。

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如何修复此错误？

此错误即将出现，因为如果

post

数据不可用，将出现的

位置就是查询。请尝试-

$query = "SELECT * FROM guest WHERE ";
if ($_POST['include2'] == "yes") {
$guestNameLast = isset($_POST['guestNameLast']) ? $_POST['guestNameLast'] :     '';
$query .= "guestNameLast LIKE '%$guestNameLast%' ";
$msg .="guest that <b>" . $guestNameLast . "</b><br/>";

$query=“选择*来自来宾”；
如果（$_POST['include2']==“是”）{
$guestNameLast=isset（$_POST['guestNameLast']）？$_POST['guestNameLast']：''；
$query.=“WHERE”；
$query.=“guestNameLast类似“%$guestNameLast%””；
$msg.=“guest that”。$guestNameLast.
；
向where子句添加一个条件。因此，如果
$\u POST['guestNameLast']
为空，则不会抛出错误：

$query = "SELECT * FROM guest ";
if ($_POST['include2'] == "yes") {
$guestNameLast = isset($_POST['guestNameLast']) ? $_POST['guestNameLast'] :     '';
$query .= " WHERE ";
$query .= "guestNameLast LIKE '%$guestNameLast%' ";
$msg .="guest that <b>" . $guestNameLast . "</b><br/>";

$query=“从来宾中选择*，其中1=1”；
如果（$_POST['include2']==“是”）{
$guestNameLast=isset（$_POST['guestNameLast']）？$_POST['guestNameLast']：''；
$query.=“和guestNameLast类似“%$guestNameLast%””；
$msg.=“guest that”。$guestNameLast.
；
添加WHERE子句，并在If条件中检查$\u POST['guestNameLast']是否为空

$query = "SELECT * FROM guest WHERE 1=1 ";
if ($_POST['include2'] == "yes") {
$guestNameLast = isset($_POST['guestNameLast']) ? $_POST['guestNameLast'] :     '';
$query .= " AND guestNameLast LIKE '%$guestNameLast%' ";
$msg .="guest that <b>" . $guestNameLast . "</b><br/>";

$query=“选择*来自来宾，其中1”；
如果（$_POST['include2']==“是”）
{
如果（设置（$_POST['guestNameLast']）和（$_POST['guestNameLast']）！=“”）
{
$guestNameLast=修剪（$_POST['guestNameLast']）；
$query.=“和guestNameLast类似“%$guestNameLast%””；
}
$msg.=“guest that”。$guestNameLast.
；
如果只有
guestNameLast

$query = "SELECT * FROM guest WHERE 1 ";
if ($_POST['include2'] == "yes") 
{
if(isset($_POST['guestNameLast']) && ($_POST['guestNameLast'] != ""))
 {
 $guestNameLast = trim($_POST['guestNameLast']);
$query .= " AND guestNameLast LIKE '%$guestNameLast%' ";
 }


$msg .="guest that <b>" . $guestNameLast . "</b><br/>";

$query=“选择*来自来宾”；
如果（$_POST['include2']==“是”）{
$guestNameLast=''；
如果（设置（$_POST['guestNameLast']）和修剪（$_POST['guestNameLast']））
{
$guestNameLast=修剪（$_POST['guestNameLast']）；
$query.=“其中guestNameLast类似“%$guestNameLast%””；
}
$msg.=“guest that”。$guestNameLast.
；
Print/log$query，然后再运行，这样您就可以看到生成的SQL是什么了
$query = "SELECT * FROM guest";

if ($_POST['include2'] == "yes") {

$guestNameLast = '';
if(isset($_POST['guestNameLast']) && trim($_POST['guestNameLast']))
{
    $guestNameLast = trim($_POST['guestNameLast']);
    $query .= " WHERE  guestNameLast LIKE '%$guestNameLast%' ";
}

$msg .="guest that <b>" . $guestNameLast . "</b><br/>";