MYSQL SUM的正负值

Question

I have a column name 'AmountLC' in the db table. Another column name 'DebitCredit' determines whether the 'AmountLC' is Positive or Negative. If DebitCredit="H", the values in AmountLC is Negative. If DebitCredit="S", the values in AmountLC is Positive. I need to make query to get the sum of AmountLC. I have tried to get the logic but didn't get any. I would be grateful if anyone can help me.

I tried the below code as per other stackoverflow discussions.

$F7 = mysql_query("SELECT 
                SUM(CASE WHEN DebitCredit='H' THEN DebitCredit ELSE 0 END) as NegativeTotal,
                SUM(CASE WHEN DebitCredit='S' THEN DebitCredit ELSE 0 END) as PostiveTotal 
                FROM T1_CSV_Table 
                WHERE Month='$getMonth' AND TaxCode='A0'");

THANKS! Update Code

$F7 = mysql_query("SELECT 
                    SUM(CASE WHEN DebitCredit='H' THEN AmountLC*-1 ELSE AmountLC END) as Total 
                    FROM T1_CSV_Table 
                    WHERE Month='$getMonth' AND TaxCode='A0'");
    $rowf7 = mysql_fetch_array($F7);
    echo "Total-".$rowf7['Total'];

Update code for results: SELECT AmountLC,DebitCredit FROM T1_CSV_Table WHERE TaxCode="A0" AND Month="12"

Answer 1

You can do that calculation all in one go if all you want is a total of the debits and credits

SELECT 
    SUM(CASE WHEN DebitCredit='H' THEN AmountLC*-1 ELSE AmountLC END) as Total
FROM T1_CSV_Table 
WHERE Month='$getMonth' AND TaxCode='A0'

NOTE: Your script is at risk of SQL Injection Attack Have a look at what happened to Little Bobby Tables Even if you are escaping inputs, its not safe! Use prepared parameterized statements