Concatenate queries in SQL using PHP

Question

I cannot spot the difference of these queries.

$lastact="SELECT * FROM DOC_DETAILS WHERE 1=1 AND DOC_TYPE=$emp_id";    
$whr="";

1. ...

$docfk=$emprow['ICID'];
$whr .= " AND DOC_TYPE=$docfk";
$qry1=mysqli_query($conn,$lastact .$whr);

...

2. ...

$qry1=mysqli_query($conn,"SELECT * FROM DOC_DETAILS WHERE 1=1 AND DOC_FK=$docfk");

...

the 1st query doesn't return any result while the 2nd works fine.

Thanks very much for any help.

Answer 1

The SQL in the first query will be

SELECT * FROM DOC_DETAILS WHERE 1=1 AND DOC_TYPE=$emp_id AND DOC_TYPE=$docfk

If emp_id and docfk are different this will return no results.

Answer 2

在第一个查询中，您添加“ DOC_TYPE = $ emp_id”，但在第二个查询中， “ DOC_TYPE = $ emp_id”未找到此条件，因此首先需要检查此条件，如果没有得到结果，请添加/删除，然后再次告诉我