Two table compare and list php [closed]

there are two different tables. I want to find the expressions with “%USD” in the columns of the same name in these two tables do not match and list them on the screen.

Table 1 query;

<?php
include("db.php");
$queb = $conn->query("select distinct symbol from tableA WHERE symbol LIKE '%USD'"); 
while ($resb = $queb->fetch_assoc()){
$symbolb = $resb['symbol'];
}

?>

table 2 query;

<?php
include("db.php");
$quec = $conn->query("select distinct symbol from tableB WHERE symbol LIKE '%USD'"); 
while ($resc = $quec->fetch_assoc()){
$symbolc = $resc['symbol'];

}
?>

How can I list expressions that are not between two tables?

Answer

I may not be understanding your question fully. If you want to list symbols that begin with ‘USD’ that are in tableA but not in tableB along with symbols in tableB that begin with USD that are not in tableA, then the following query should return those symbols:

select distinct symbol from tableA
    where symbol LIKE '%USD' and symbol not in (select distinct symbol from tableB)
union
select distinct symbol from tableB
    where symbol LIKE '%USD' and symbol not in (select distinct symbol from tableA)

Or you can use outer joins instead:

select distinct symbol from tableA left join tableB on tableA.symbol = tableB.symbol
    where tableA.symbol like ('%USD') and tableB.symbol is null
union
select distinct symbol from tableB left join tableA on tableB.symbol = tableA.symbol
    where tableB.symbol like ('%USD') and tableA.symbol is null

In either case, performance will be improved in you have indexes on the symbol columns.