Can someone explain to me why this does not work?
inq := "6,7" //strings.Join(artIds, ",")
rows, err = db.Query("SELECT DISTINCT title FROM tags_for_articles LEFT JOIN tags ON tags.id = tags_for_articles.tag_id WHERE article_id IN (?)", inq)
And this does
rows, err = db.Query("SELECT DISTINCT title FROM tags_for_articles LEFT JOIN tags ON tags.id = tags_for_articles.tag_id WHERE article_id IN (6,7)", inq)
I'm trying to do a simple IN clause with a slice of ints, and every solution suggested doesn't seem very idiomatic
Tried to do this, but the problem appears to be the string substitution.
inq := strings.Join(artIds, ",")
I'm a bit surprised that go doesn't seem to have a graceful way to handle this query.
If you have been careful to build your inq string from real ints (to avoid injection), you can just build the string yourself and avoid using ?:
inq := "6,7"
sql := fmt.Sprintf("SELECT DISTINCT title FROM tags_for_articles LEFT JOIN tags ON tags.id = tags_for_articles.tag_id WHERE article_id IN (%s)",inq)
rows, err := db.Query(sql)
If you do it a lot, better to have a WhereIn function that does this for you, or use an orm. Be careful which args you accept though, as if you accept arbitrary strings anything could be injected.
Because database/sql does not inspect your query and it passes your arguments directly to the driver, it makes dealing with queries with IN clauses difficult:
SELECT * FROM users WHERE level IN (?);
When this gets prepared as a statement on the backend, the bindvar ? will only correspond to a single argument, but what is often desired is for that to be a variable number of arguments depending on the length of some slice
var levels = []int{4, 6, 7}
rows, err := db.Query("SELECT * FROM users WHERE level IN (?);", levels)
There is a way to handle these types of queries using sqlx package which provide more control over database queries.
This pattern is possible by first processing the query with sqlx.In:
var levels = []int{4, 6, 7}
query, args, err := sqlx.In("SELECT * FROM users WHERE level IN (?);", levels)
For more information Go through Godoc for InQueries