How to append URI as string in SQL query - sql

Question

Looks simple but I unable to make it happen.
When browsing domain.com/post/1, it should show data from row id which value 1.
Row id is integer (int4).
Below the the codes, which is not working:
package main
import "fmt"
import "github.com/go-martini/martini"
import "net/http"
import "database/sql"
import _ "github.com/lib/pq"
func SetupDB() *sql.DB {
db, err := sql.Open("postgres", "user=postgres password=apassword dbname=lesson4 sslmode=disable")
PanicIf(err)
return db
}
func PanicIf(err error) {
if err != nil {
panic(err)
}
}
func main() {
m := martini.Classic()
m.Map(SetupDB())
m.Get("/post/:idnumber", func(rw http.ResponseWriter, r *http.Request, db *sql.DB) {
rows, err := db.Query(`SELECT title, author, description FROM books WHERE id = params["idnumber"]`)
PanicIf(err)
defer rows.Close()
var title, author, description string
for rows.Next() {
err:= rows.Scan(&title, &author, &description)
PanicIf(err)
fmt.Fprintf(rw, "Title: %s\nAuthor: %s\nDescription: %s\n\n",
title, author, description)
}
})
m.Run()
}

Answer 1

Part of your issue is that you're using the string params["idnumber"] as part of the SQL query
db.Query(`SELECT title, author, description FROM books WHERE id = params["idnumber"]`)
That will look for a book where the id equals params["idnumber"] string.
What you need to do is use placeholders and the arguments according to http://golang.org/pkg/database/sql/#DB.Query
In this case your query should be
db.Query("SELECT title, author, description FROM books WHERE id=$1", params["idnumber"])
That should solve the issue I think you're having. However, until you actually update your question with the actual issue you're having I won't know.
Update
The error you're getting with undefined: params is because you don't have a params object in scope.
I'd suggest reading how martini works in regards of getting the arguments out of the route. https://github.com/go-martini/martini#routing

Answer 2

I think the problem is that you're using the variable name in your string literal query, you want it's value there instead.
Try changing this;
rows, err := db.Query(`SELECT title, author, description FROM books WHERE id = params["idnumber"]`)
to;
rows, err := db.Query("SELECT title, author, description FROM books WHERE id =$1", params["idnumber"])
You could have other issues beyond that but given you're not forming the query correctly I wouldn't expect you to get back the results you want.