Question

I have table :

=========================================================================
| id | stem_before | stem_after | stem_freq | sentence_id | document_id | 
=========================================================================
|  1 |     a       |     b      |    1      |   0         |       1     |    
|  2 |     c       |     d      |    1      |   0         |       1     |        
|  3 |     e       |     f      |    1      |   1         |       1     |
|  4 |     g       |     h      |    1      |   2         |       1     |
|  5 |     i       |     j      |    2      |   0         |       2     |
|  6 |     k       |     l      |    1      |   0         |       2     |
=========================================================================

I want to count in 2 steps :
step one is divide 1 with the sum the value of stem_freq in every sentence_id and document_id. step two is multiplication the result of the first step with the value of stem_freq

for example :

for data with document_id = 1 and sentence_id = 0, first step: 1/(1+1) = 0.5, second step for id = 1 is 1*0.5 = 0.5. for id = 2 is 1*0.5 = 0.5.

for data with document_id = 2 and sentence_id = 0, first step: 1/(2+1) = 0.3333, second step for id = 5 is 2*0.3333 = 0.6666, for id = 6 is 1*0.3333 = 0.3333.

here’s my code :

$query = mysql_query ("SELECT sentence_id, document_id, stem_after, 
stem_freq,SUM(stem_freq) as freq 
FROM tb_stemming 
WHERE document_id ='$doc_id' 
GROUP BY(sentence_id)");

while ($row = mysql_fetch_array($query)) {
   $a    = $row['freq'];
   $freq = $row['stem_freq'];
   $tf   = $freq/$a;
}

but it only gives me result of the first data in every different sentence : can you help me. thank you 🙂

Answer 1

Try this:

SELECT
    a.*, 
    a.stem_freq * b.value
FROM
    tb_stemming as a
    JOIN 
    (
        SELECT
            document_id,
            sentence_id,
            1 / sum(stem_freq) 'value'
        FROM
            tb_stemming
        GROUP BY document_id, sentence_id
    ) as b
    ON a.document_id = b.document_id AND a.sentence_id = b.sentence_id