Get get number of rows using sql in golang

db.go

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)
    }
}

@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.

var count int
stmt, err = db.Prepare("SELECT COUNT(*) as count FROM YourTable")
if err != nil { log.Fatal(err) }
err = stmt.QueryRow().Scan(&count)
if err != nil { log.Fatal(err) }
log.Println(count)
stmt.Close() // or use defer rows.Close(), idc

Refference:
Go database/sql tutorial

The code here by trkrameshkumar is great though if you need to use the count functions often in various situations. WIll minimize your code, and make it more readable.

Cheers

Hi guys,

I am using the function checkCount() and it works fine.
The thing is when I call it twice in a row, the second time it returns 0.

I guess rows is not reset, is there a easy way to make the method reusable ?
Sorry if it 's a dumb question, It's literally my second day with GoLang

it is very goods!