How to Export & Import Existing User (with its Privileges!)

Question

I have an existing MySQL instance (test), containing 2 databases and a few users each having different access privileges to each database.

I now need to duplicate one of

Answer 1

I tackled this with a small C# program. There is code here to generate a script or apply the grants directly from source to destination. If porting from a Windows -> *nix environment you may have to consider case sensitivity issues.

using System;
using MySql.Data.MySqlClient;
using System.Configuration;
using System.IO;
using System.Collections.Generic;

namespace GenerateUsersScript
{
    class Program
    {
        static void Main(string[] args)
        {
            List<string> grantsQueries = new List<string>();

            // Get A Show Grants query for each user
            using (MySqlConnection sourceConn = OpenConnection("sourceDatabase"))
            {
                using (MySqlDataReader usersReader = GetUsersReader(sourceConn))
                {
                    while (usersReader.Read())
                    {
                        grantsQueries.Add(String.Format("SHOW GRANTS FOR '{0}'@'{1}'", usersReader[0], usersReader[1]));
                    }
                }

                Console.WriteLine("Exporting Grants For {0} Users", grantsQueries.Count);

                using (StreamWriter writer = File.CreateText(@".\UserPermissions.Sql"))
                {
                    // Then Execute each in turn 
                    foreach (string grantsSql in grantsQueries)
                    {
                        WritePermissionsScript(sourceConn, grantsSql, writer);
                    }

                    //using (MySqlConnection destConn = OpenConnection("targetDatabase"))
                    //{
                    //    MySqlCommand command = destConn.CreateCommand();

                    //    foreach (string grantsSql in grantsQueries)
                    //    {
                    //        WritePermissionsDirect(sourceConn, grantsSql, command);
                    //    }
                    //}
                }
            }

            Console.WriteLine("Done - Press A Key to Continue");

            Console.ReadKey();
        }

        private static void WritePermissionsDirect(MySqlConnection sourceConn, string grantsSql, MySqlCommand writeCommand)
        {
            MySqlCommand cmd = new MySqlCommand(grantsSql, sourceConn);

            using (MySqlDataReader grantsReader = cmd.ExecuteReader())
            {
                while (grantsReader.Read())
                {
                    try
                    {
                        writeCommand.CommandText = grantsReader[0].ToString(); 

                        writeCommand.ExecuteNonQuery();
                    }
                    catch (Exception ex)
                    {
                        Console.WriteLine(grantsReader[0].ToString());

                        Console.WriteLine(ex.Message);
                    }
                }
            } 
        }

        private static void WritePermissionsScript(MySqlConnection conn, string grantsSql, StreamWriter writer)
        {
            MySqlCommand command = new MySqlCommand(grantsSql, conn);

            using (MySqlDataReader grantsReader = command.ExecuteReader())
            {
                while (grantsReader.Read())
                {
                    writer.WriteLine(grantsReader[0] + ";");
                }
            }

            writer.WriteLine();
        }

        private static MySqlDataReader GetUsersReader(MySqlConnection conn)
        {
            string queryString = String.Format("SELECT User, Host FROM USER");
            MySqlCommand command = new MySqlCommand(queryString, conn);
            MySqlDataReader reader = command.ExecuteReader();
            return reader;
        }

        private static MySqlConnection OpenConnection(string connName)
        {
            string connectionString = ConfigurationManager.ConnectionStrings[connName].ConnectionString;
            MySqlConnection connection = new MySqlConnection(connectionString);
            connection.Open();
            return connection; 

        }
    }
}

with an app.config containing ...

    <connectionStrings>
        <add name="sourceDatabase" connectionString="server=localhost;user id=hugh;password=xxxxxxxx;persistsecurityinfo=True;database=MySql" />
        <add name="targetDatabase" connectionString="server=queeg;user id=hugh;password=xxxxxxxx;persistsecurityinfo=True;database=MySql" />
    </connectionStrings> 

Answer 2

A PHP script to loop over your users to get the grant commands would be as such:

// Set up database root credentials
$host = 'localhost';
$user = 'root';
$pass = 'YOUR PASSWORD';
// ---- Do not edit below this ----
// Misc settings
header('Content-type: text/plain; Charset=UTF-8');
// Final import queries goes here
$export = array();
// Connect to database
try {
    $link = new PDO("mysql:host=$host;dbname=mysql", $user, $pass);
} catch (PDOException $e) {
    printf('Connect failed: %s', $e->getMessage());
    die();
}

// Get users from database
$statement = $link->prepare("select `user`, `host`, `password` FROM `user`");
$statement->execute();
while ($row = $statement->fetch())
{
    $user   = $row[0];
    $host   = $row[1];
    $pass   = $row[2];
    $export[] = 'CREATE USER \''. $user .'\'@\''. $host .'\' IDENTIFIED BY \''. $pass .'\'';
    // Fetch any permissions found in database
    $statement2 = $link->prepare('SHOW GRANTS FOR \''. $user .'\'@\''. $host .'\'');
    $statement2->execute();
    if ($row2 = $statement2->fetch())
    {
        $export[] = $row2[0];
    }
}

$link = null;
echo implode(";\n", $export);

Gist: https://gist.github.com/zaiddabaeen/e88a2d10528e31cd6692

Answer 3

I had the same problem. The solution is that after the import of the backup you need to do a "flush privileges;". Then the privileges of the users will be active as in the original database.

SO

mysql -u root -p -h localhost secondb < secondb_schema.sql

mysql -u root; then in mysql: "flush privileges;"