Question

下面的一些变量（us1或sp1 ..）可能具有空值（客户有可能不填写相应的文本视图）。我怎么能语法＆＃34;哪里＆＃34;只有＆＃34; not null＆＃34;变量;例如，当us1不为null且sp1为null时，＆＃34;其中＆＃34;条款必须是：＆＃34; customer.username1 =＆＃39; us1＆＃39; ＆＃34; 提前致谢

$us1 = $_POST['username1'];
$sp1 = $_POST['startPoli1'];

SELECT `username1`,`startPoli1`, `finalPoli1`,`weight1` ,`phone1` 
 FROM customer ,registration1 
 where  customer.startPoli1 = 'sp1' and customer.username1 = 'us1'

Answer 1

以这种方式写下条件：

WHERE ('sp1' IS NULL OR customer.startPoli1 = 'sp1')
AND ('us1' IS NULL OR customer.username1 = 'us1')

Answer 2

像这样：

$us1 = $_POST['username1'];
$sp1 = $_POST['startPoli1'];

$sql = "SELECT `username1`,`startPoli1`, `finalPoli1`,`weight1` ,`phone1` 
 FROM customer ,registration1 where 1=1 ";

if($sp1 != null)
   $sql += "and customer.startPoli1 = 'sp1'";
if($us1 != null) 
   $sql += "and customer.username1 = 'us1'";

Answer 3

我认为 - 这是有问题的错误。忘记了$ sp1和$ us1是变量

$us1 = $_POST['username1'];
$sp1 = $_POST['startPoli1'];

$sql = "SELECT `username1`,`startPoli1`, `finalPoli1`,`weight1` ,`phone1` 
 FROM customer ,registration1 where 1=1 ";

if($sp1 != null)
   $sql += "and customer.startPoli1 = '" + $sp1 + "'";
if($us1 != null) 
   $sql += "and customer.username1 = '" + $us1 + "'";

where子句，不带空变量

3 个答案: