How to Count the Number of Rows in a Database Table with Go?

Count Number of Rows in Go: A Step-by-Step Guide

Counting the number of rows in a database table using Go is a common task in web development and data processing. Here's how to achieve this efficiently:

1. Initialize Variable for Count

Declare a variable to store the number of rows, typically an integer named count.

2. Query the Database (Option 1: Query)

Use the db.Query function to execute a SQL statement that counts the rows in a table. The statement should be SELECT COUNT(*) FROM .

3. Read Row and Assign Count

After executing the query, use a loop to read each row returned by the database. Within the loop, use the Scan function to assign the value of the count column to the count variable.

4. Query the Database (Option 2: QueryRow)

If you expect to retrieve only one row, you can use the db.QueryRow function instead. This simplifies the process as it reads the single row without the need for loops.

5. Print the Count

Finally, use fmt.Printf to display the count variable as a readable string.

Example 1 (Query)

package main

import (
    "database/sql"
    "fmt"
    "log"

    _ "github.com/go-sql-driver/mysql"
)

func main() {
    db, err := sql.Open("mysql", "user:password@tcp(host:port)/database")
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()

    count := 0

    rows, err := db.Query("SELECT COUNT(*) FROM main_table")
    if err != nil {
        log.Fatal(err)
    }
    defer rows.Close()

    for rows.Next() {
        if err := rows.Scan(&count); err != nil {
            log.Fatal(err)
        }
    }

    fmt.Printf("Number of rows: %d\n", count)
}

Example 2 (QueryRow)

package main

import (
    "database/sql"
    "fmt"
    "log"

    _ "github.com/go-sql-driver/mysql"
)

func main() {
    db, err := sql.Open("mysql", "user:password@tcp(host:port)/database")
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()

    var count int

    err = db.QueryRow("SELECT COUNT(*) FROM main_table").Scan(&count)
    switch {
    case err != nil:
        log.Fatal(err)
    default:
        fmt.Printf("Number of rows: %d\n", count)
    }
}

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