如何在单个查询中搜索多个用户名

I want to search for some username in my database like this->

$skip = $_POST['username'];
$_SESSION['skip_user'] = array();
array_push($_SESSION['skip_user'],$skip);
$str = $_SESSION['skip_user'];
$string = rtrim(implode(',', $str), ',');

Now string variable looks like "name1, name2, name3";

mysqli_query($db, "SELECT * FROM users WHERE username in ({$string}) ORDER BY id DESC");

This fetches the users but i don't want these users. I mean is there any query where i can i write WHERE username !in ({$string})!

get all users except "name1, name2, name3" these users

Now after adding NOT IN I'm receiving error

mysqli_query($db, "SELECT * FROM users  WHERE username NOT IN ({$string}) ORDER BY id DESC")or die(mysqli_error($db)); php is giving error Unknown column 'name1' in 'where clause'

Try NOT IN in the SQL query.

First though try to add quotes to the values you are trying in the NOT IN part of the sql query.

$str = '';
foreach ($_SESSION['skip_user'] AS $word) {
    $str .= "'$word',";
}
$str = rtrim($str, ',');

Then use this $str in your query. Also, try to make a habit out of using `` for column names, like this:

SELECT `SOMETHING` FROM `TABLE_NAME` WHERE <CONDITION>

I hope that helps!

You should use NOT IN to exclude certain values.

mysqli_query($db, "SELECT * FROM users WHERE username NOT IN ('name1', 'name2') ORDER BY id DESC");

yep, just type "not" instead of "!"

select * from table where junk not in ('item1', 'item2', 'item3');

1) You have a few other problems though you're not adding quotes to your implode:

// you need quotes here
$string = implode("','", $str);
// And here
mysqli_query($db, "SELECT * FROM users WHERE username in ('{$string}') ORDER BY id DESC");

However, this is what you should really be doing.

2) You should bind your parameters instead as you're open to SQL injection:

$params = array();
$params[0] = "";
$sql = "SELECT * FROM users WHERE username NOT IN (";
foreach($str as $s){
    $params[0] .= "s";
    array_push($params, $s);
    $sql .= "?, ";
}
$sql = rtrim($sql, " ,").") ORDER BY id DESC";

$stmt = $conn->prepare($sql);

// this is the same as doing: $stmt->bind_param('s', $param);
call_user_func_array(array($stmt, 'bind_param'), $params);

// execute and get results
$stmt->execute();