PHP compares different data from two tables

PHP compares different data in two tables

SQL statement to compare table data:

(select *
        from EMP
        minus
        select *from EMP2)
union 
(select *
       from EMP2
       minus
       select * from EMP)

Note: The premise is that the table structure is the same, you can perform data difference query

The following results are obtained:

Result: The difference between the two tables with the same structure is obtained Data

But it is impossible to distinguish which row of data belongs to which table, so a subquery is added and the virtual column name is used to distinguish. The sql is as follows:

select a.*,'EMP' from (select *
          from EMP
        minus
        select * FROM EMP2)  a
        
union 
select b.*,'EMP2' from
(select *
         from EMP2
       minus
       select * FROM EMP) b

The obtained query The result is as follows:

Result: EMP line is added to distinguish;

Finally, use php to implement it:

<?php
$serve = &#39;localhost:3306&#39;;
$username = &#39;root&#39;;
$password = &#39;admin123&#39;;
$dbname = &#39;examples&#39;;
$link = mysqli_connect($serve,$username,$password,$dbname);
mysqli_set_charset($link,&#39;UTF-8&#39;); // 设置数据库字符集
$result = mysqli_query($link,"select a.*,&#39;EMP&#39; from (select * from EMP minus select * FROM EMP2) a union select b.*,&#39;EMP2&#39; from (select * from EMP2 minus select * FROM EMP) b");
while ($row = mysqli_fetch_assoc($result)) {   

}
?>

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