Question

I have a table of keywords with an integer weight associated with it. In another table I have a table of texts. I would like to compute the value of each text by finding the keywords and summing the weights in the text. Is there a way to do this entirely in SQL?

Answer 1

If you represent your texts as

| text_id | count | word      |
|---------+-------+-----------|
|       1 |     1 | nice      |
|       1 |     2 | weather   |
|       1 |     3 | no?       |
|       2 |     1 | Mayer     |
|       2 |     2 | Hawthorne |
|       2 |     3 | has       |
|       2 |     4 | soul      |

where text with ID 1 is “nice weather no?”, for example, you can calculate the text scores using the keyword table

| keyword   | weight |
|-----------+--------|
| weather   |      2 |
| nice      |      3 |
| Hawthorne |     10 |
| soul      |      5 |

with

SELECT t.text_id AS text_id, SUM(k.weight) AS score
FROM texts t
LEFT JOIN keywords k
ON k.keyword == t.word
GROUP BY t.text_id;

resulting in

| text_id | score |
|---------+-------|
|       1 |     5 |
|       2 |    15 |