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Get get number of rows using sql in golang
package main
import (
"database/sql"
"fmt"
_ "github.com/lib/pq"
)
const (
DB_USER = "ramesh"
DB_PASSWORD = "secret"
DB_NAME = "test_db"
)
func main() {
dbinfo := fmt.Sprintf("user=%s password=%s dbname=%s sslmode=disable",
DB_USER, DB_PASSWORD, DB_NAME)
db, err := sql.Open("postgres", dbinfo)
checkErr(err)
defer db.Close()
rows, err := db.Query("SELECT COUNT(*) as count FROM table_name")
fmt.Println("Total count:",checkCount(rows))
checkErr(err)
}
func checkCount(rows *sql.Rows) (count int) {
for rows.Next() {
err:= rows.Scan(&count)
checkErr(err)
}
return count
}
func checkErr(err error) {
if err != nil {
panic(err)
}
}

Thank you!

froind commented Jul 23, 2016

not sure how i feel about go at the minute. between this and unmarshalling json its a bit of a pain. also attempt batch inserts into a table. F**k

gokca commented Feb 17, 2017

also u can:
rows := db.QueryRow("you're select count....")
rows.Scan(&count)
return count

And you will not use "for" .

agis commented Apr 28, 2017

As @gokca suggested, this can be done in a simpler way: https://gist.github.com/agis/7e8cd4c7a20d037c01e663402fcad9d0

betasve commented May 1, 2017

Actually, AFAIK, db.QueryRow("...") is the right way. db.Query() has to be avoided for DB results that return only one row. Also in the case above, it's strongly recommended to use defer rows.Close() right after receiving rows or DB connections will start leaking

@betasve What, why does Query have to be avoided for results that return only one row? I have code that is working that queries a lookup table and panics if there is more than one entry. I don't see anything in the docs to suggest that is a problem. Furthermore, the QueryRow documentation says

QueryRow executes a query that is expected to return at most one row. QueryRow always returns a non-nil value. Errors are deferred until Row's Scan method is called.

Expected to return, but not required to return. I read that to say there could be duplicates and there is no way to tell. I think it is just a convenience function.

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