Fetching query dynamically with Golang

dynamic_fetch_query.go

package main

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

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

func main() {
    dsn := "user:password@tcp(127.0.0.1:3306)/testdb"
    db, err := sql.Open("mysql", dsn)
    if err != nil {
        log.Fatalf("Error opening database connection: %v", err)
    }
    defer db.Close()

    // Test connection
    err = db.Ping()
    if err != nil {
        log.Fatalf("Error pinging database: %v", err)
    }
    fmt.Println("Successfully connected to the database!")

    // SQL Query
    query := "SELECT id, name, age, email FROM users"
    rows, err := db.Query(query)
    if err != nil {
        log.Fatalf("Error executing query: %v", err)
    }
    defer rows.Close()

    // Get column names
    columns, err := rows.Columns()
    if err != nil {
        log.Fatalf("Failed to get column names: %v", err)
    }

    // Create slices for holding row data
    var rowData []interface{}
    for rows.Next() {
        rowData = make([]interface{}, len(columns))
        rowPointers := make([]interface{}, len(columns))
        for i := range rowData {
            rowPointers[i] = &rowData[i]
        }

        if err := rows.Scan(rowPointers...); err != nil {
            log.Printf("Failed to scan row: %v", err)
            continue
        }

        // Print data dynamically based on column names
        for i, data := range rowData {
            // Check if data is not nil before printing
            if data != nil {
                switch v := data.(type) {
                case []byte:
                    fmt.Printf("%s: %s\n", columns[i], v)
                default:
                    fmt.Printf("%s: %v\n", columns[i], v)
                }
            }
        }
        fmt.Println("---") // Separator between rows
    }

    // Check for errors after iteration
    if err := rows.Err(); err != nil {
        log.Printf("Error in rows: %v", err)
    }

    fmt.Println("Database operations completed.")
}