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 t

Answer 1

This assumes DocumentID and Tag are the Primary Key.

Edit: Changed HAVING clause to count DISTINCT tags. That way it doesn't matter what the primary key is.

Test Data

-- Populate Test Data
CREATE TABLE #table (
  DocumentID varchar(8) NOT NULL, 
  Tag varchar(8) NOT NULL
)

INSERT INTO #table VALUES ('1','tag1')
INSERT INTO #table VALUES ('1','tag2')
INSERT INTO #table VALUES ('1','tag3')
INSERT INTO #table VALUES ('2','tag2')
INSERT INTO #table VALUES ('3','tag1')
INSERT INTO #table VALUES ('3','tag2')
INSERT INTO #table VALUES ('4','tag1')
INSERT INTO #table VALUES ('5','tag3')

INSERT INTO #table VALUES ('3','tag2')  -- Edit: test duplicate tags

Query

-- Return Results
SELECT DocumentID FROM #table
WHERE Tag IN ('tag1','tag2')
GROUP BY DocumentID
HAVING COUNT(DISTINCT Tag) = 2

Results

DocumentID
----------
1
3