プログラム C# クラス DB接続 SQLServer - git0331-lgtm/Knowledge GitHub Wiki

using System;
using System.Data;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace XXX
{
    public class SqlHelper
    {
        private string _connectionString;

        public SqlHelper(string connectionString)
        {
           // Server=myserver;Database=mydb;User Id=myuser;Password=mypassword;
            _connectionString = connectionString;
        }

        // クエリ実行
        public DataTable ExecuteQuery(string query)
        {
            string dbName = ExtractDatabaseName(_connectionString);

            DataTable dataTable = new DataTable();
            using (SqlConnection connection = new SqlConnection(_connectionString))
            {
                try
                {
                    connection.Open();
                    using (SqlCommand command = new SqlCommand(query, connection))
                    {
                        using (SqlDataAdapter adapter = new SqlDataAdapter(command))
                        {
                            adapter.Fill(dataTable);
                        }
                    }
                }
                catch (Exception ex)
                {
                    MessageBox.Show($"接続先DB : {dbName}\n実行クエリ : {query}\n" + "\n" +
                                     "エラー詳細 : " + ex.Message,
                                     "エラー",
                                    MessageBoxButtons.OK,
                                    MessageBoxIcon.Error);

                    return null;
                }
            }

            return dataTable;
        }

        // DB名取得
        private string ExtractDatabaseName(string connectionString)
        {
            var dbNameValue = connectionString.Split(';')[1].Split('=')[1];  // "Database=xxx"部分を取得
            return dbNameValue;
        }
    }
}