SQL query that gives distinct results that match multiple columns

Question

Sorry, I couldn't provide a better title for my problem as I am quite new to SQL. I am looking for a SQL query string that solves the below problem. Let's assume the following table: ``` DOCUMENT_ID | TAG ---------------------------- 1 | tag1 1 | tag2 1 | tag3 2 | tag2 3 | tag1 3 | tag2 4 | tag1 5 | tag3 ``` Now I want to select all distinct document id's that contain one or more tags (but those must provide all specified tags). For example: Select all document_id's with tag1 and tag2 would return 1 and 3 (but not 4 for example as it doesn't have tag2). What would be the best way to do that? Regards, Kai

Accepted Answer

```
SELECT document_id
FROM table
WHERE tag = 'tag1' OR tag = 'tag2'
GROUP BY document_id
HAVING COUNT(DISTINCT tag) = 2
```

Edit:

Updated for lack of constraints...

SQL query that gives distinct results that match multiple columns

Solution

Problem