How to implement error handling for database operations in Go?

In Go, you can implement error handling for database operations by utilizing the built-in error handling features along with the database/sql package. Here's a general approach:

Establish a database connection: Start by opening a connection to your database using the database/sql package. It provides a consistent interface for working with different databases.

import (
    "database/sql"
    _ "github.com/go-sql-driver/mysql" // Import the database driver for your specific database
)

func main() {
    db, err := sql.Open("mysql", "user:password@tcp(localhost:3306)/dbname")
    if err != nil {
        // Handle the error
        log.Fatal(err)
    }
    defer db.Close()

    // Database operations...
}

Execute queries: Use prepared statements or raw queries to execute operations on the database. The sql.DB.Query(), QueryRow(), and Exec() functions return sql.Result or sql.Rows, along with an error.

// Executing a query
result, err := db.Exec("INSERT INTO users (name, email) VALUES (?, ?)", "John Doe", "[email protected]")
if err != nil {
    // Handle the error
    log.Fatal(err)
}

// Executing a prepared statement
stmt, err := db.Prepare("UPDATE users SET name = ? WHERE id = ?")
if err != nil {
    // Handle the error
    log.Fatal(err)
}
defer stmt.Close()

result, err := stmt.Exec("Jane Smith", 1)
if err != nil {
    // Handle the error
    log.Fatal(err)
}

Handling errors: Handle errors according to your application's requirements. Some common approaches include logging the error, returning an error to the caller, or retrying the operation.

// Returning the error to the caller
func createUser(name, email string) error {
    _, err := db.Exec("INSERT INTO users (name, email) VALUES (?, ?)", name, email)
    if err != nil {
        return fmt.Errorf("failed to create user: %w", err)
    }
    // Success
    return nil
}

// Logging the error
result, err := db.Exec("DELETE FROM users WHERE id = ?", 1)
if err != nil {
    log.Println("failed to delete user:", err)
}

// Retry operation
for retries := 0; retries < maxRetries; retries++ {
    result, err := db.Exec("UPDATE users SET name = ? WHERE id = ?", name, id)
    if err != nil {
        log.Println("failed to update user:", err)
        continue // Retry
    }
    // Success, exit loop
    break
}

By incorporating these practices, you can effectively handle errors in your Go code while performing database operations.