我有以下代码:
$var1 = NULL;
$var2 = NULL;
$var3 = NULL;
$var4 = NULL;
/* (...) code for logical flow condition (...) */
/* After the code, only var1 is different
*/
// $var1 = "something"
$query = "INSERT INTO (...) VALUES ('$var1','$var2','$var3','$var4');
事情是这样的:所有变量的所有字段都是唯一的。代码的问题是，数据库没有插入"$var2,3,4的重复值"，因为它插入的变量是' '而不是NULL。我希望值是NULL 但是维护它在一个连贯的查询…在一种连接中，如果你可以说，为了不破坏我的逻辑流代码的简单性…
我想要$query = "INSERT INTO (...) VALUES ('$var1','$var2','$var3','$var4');
$query = "INSERT INTO (...) VALUES ('$var1',NULL,NULL,NULL);
而不是how it is:
$query = "INSERT INTO (...) VALUES ('$var1','','','');
那么，我怎么能做到这保持变量在查询，无论是NULL和非NULL?Tyvm for your help
您需要测试该值是字符串还是null，并且只有当它是字符串时才在SQL中添加引号:
$var1_sql = $var1 === null ? "NULL" : "'$var1'";
$var2_sql = $var2 === null ? "NULL" : "'$var2'";
$var3_sql = $var3 === null ? "NULL" : "'$var3'";
$var4_sql = $var4 === null ? "NULL" : "'$var4'";
$query = "INSERT INTO (...) VALUES ($var1_sql, $var2_sql, $var3_sql, $var4_sql)";
但是最好使用准备好的查询。
$query = "INSERT INTO (...) VALUES (?, ?, ?, ?)";
$stmt = $conn->prepare($query);
$stmt->bind_param("ssss", $var1, $var2, $var3, $var4);
$stmt->execute();
试试这样:
$var1 = NULL;
$var2 = "'a value'";
$var3 = NULL;
$var4 = "'another val'";
$query = "INSERT INTO (...) VALUES ($var1,$var2,$var3,$var4)";