Novice advice: how to write php multi-condition query search MYsql

Question

According to such query conditions, how to search for the user name and password in the database?

Answer 1

Directly add multiple and   conditions after where. If the value is not selected, it will be empty.

Answer 2

Cannot upload pictures. . .

Answer 3

good

Answer 4

Add the last one yourself

Answer 5

Add the last one yourself

Answer 6

if($chengbenjia!=0){

switch ($chengbenjia) {

case 1:

$sql = $sql."and cost_price>=0 and cost_price<=99 ";

break;

case 2:

$sql = $sql."and cost_price>=100 and cost_price<200 ";

break;

case 3:

$sql = $sql."and cost_price>=200 and cost_price<=299 ";

break;

case 4:

$sql = $sql."and cost_price>=300 ";

break;

case 5:

$sql = $sql."and cost_price =0 ";

break;

}

}

if($shoujia!=0){

switch ($shoujia) {

case 1:

$sql = $sql."and sellprice>=0 and sellprice<=99 ";

break;

case 2:

$sql = $sql."and sellprice>=100 and sellprice<200 ";

break;

case 3:

$sql = $sql."and sellprice>=200 and sellprice<=299 ";

break;

case 4:

$sql = $sql."and sellprice>=300 ";

break;

}

}

我也是刚学php没多久 我用的 字符串拼接做的 有没有别的更好地办法我不太清楚