数据库实体生成小工具（C#+mysql）

using MySql.Data.MySqlClient;
using System;
using System.Collections.Generic;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DataTableToModel
{
    public class CreateModel
    {
        public CreateModel(string tableName, string connectionString)
        {
            this.TableName = tableName;
            this.ConnectionString = connectionString;
        }
        /// <summary>
        /// 表名称
        /// </summary>
        private string TableName { get; set; }
        /// <summary>
        /// 数据库链接
        /// </summary>
        private string ConnectionString { get; set; }

        private string FieldPath = @"D:\\CreateEntityByDB";

        //获取所有的数据库名
        //private static string GetAllDataSql = "SELECT NAME FROM MASTER.DBO.SYSDATABASES ORDER BY NAME";
        ////获取所有的表名
        //private static string GetAllTableSql = "SELECT name FROM sys.tables where type ='U'";
        //获取所有的表信息
        private static string GetTableInfoSql = @"SELECT DISTINCT a.COLUMN_NAME columnName, 
                                          a.DATA_TYPE typeName, a.IS_NULLABLE isnullAble,a.COLUMN_COMMENT comment
                                          From INFORMATION_SCHEMA.Columns a LEFT JOIN 
                                          INFORMATION_SCHEMA.KEY_COLUMN_USAGE b ON a.TABLE_NAME=b.TABLE_NAME ";


        //根据表名创建模型
        public string CreateSingleModel()
        {
            try
            {
                string sql = $"{GetTableInfoSql}  where a.table_name='{TableName}'";
                using (MySqlConnection conn = new MySqlConnection(ConnectionString))//ConnectionString为自己连接字符串
                {
                    MySqlCommand sqlCommand = new MySqlCommand(sql, conn);
                    conn.Open();
                    MySqlDataReader reader = sqlCommand.ExecuteReader();
                    StringBuilder stringBuilder = new StringBuilder();
                    stringBuilder.Append($"public class {TableName} \r\n{{\r\n");
                    while (reader.Read())
                    {
                        stringBuilder.Append($"///<summary>\r\n///{reader["comment"].ToString()}\r\n///</summary>\r\n");
                        stringBuilder.Append($"  public {GetTypeOfColumn(reader["typeName"].ToString(), reader["isnullAble"].ToString())} {reader["columnName"]} {{get;set;}}\r\n");
                    }
                    stringBuilder.Append("} \r\n");
                    string directory = string.IsNullOrEmpty(FieldPath) ? AppDomain.CurrentDomain.BaseDirectory + "\\Model\\" : FieldPath;//FieldPath为自己文件路径
                    StreamWriter sr;
                    //是否存在文件夹,不存在则创建
                    if (!Directory.Exists(directory))
                    {
                        Directory.CreateDirectory(directory);
                    }
                    string path = directory + "\\" + TableName + ".txt";
                    //如果该文件存在则追加内容，否则创建文件
                    if (File.Exists(path))
                    {
                        sr = File.AppendText(path);
                    }
                    else
                    {
                        sr = File.CreateText(path);
                    }
                    sr.Write(stringBuilder.ToString());
                    sr.Flush();
                    sr.Close();
                }
            }
            catch (Exception ex)
            {
                return ex.Message;
            }
            return "success";
        }
        //根据数据库直接生成所有模型
        //public  void BatchCreateModel()
        //{
        //    using (SqlConnection conn = new SqlConnection(ConnectionString))//ConnectionString为自己连接字符串
        //    {
        //        SqlCommand sqlCommand = new SqlCommand(GetAllTableSql, conn);
        //        conn.Open();
        //        SqlDataReader reader = sqlCommand.ExecuteReader();
        //        while (reader.Read())
        //        {
        //            CreateSingleModel(reader["name"].ToString());
        //        }
        //    }
        //}
        //获取列的类型
        private string GetTypeOfColumn(string type, string nullAble)
        {
            //新增类型
            if (type.Equals("tinyint") && nullAble.Equals("NO"))
                return "byte";
            else if (type.Equals("tinyint") && nullAble.Equals("YES"))
                return "byte?";
            else if (type.Equals("smallint") && nullAble.Equals("NO"))
                return "int";
            else if (type.Equals("smallint") && nullAble.Equals("YES"))
                return "int?";
            else if (type.Equals("bit") && nullAble.Equals("NO"))
                return "bool";

            else if (type.Equals("int") && nullAble.Equals("NO"))
                return "int";
            else if (type.Equals("int") && nullAble.Equals("YES"))
                return "int?";
            else if (type.Equals("bit") && nullAble.Equals("Not"))
                return "bool";
            else if (type.Equals("bit") && nullAble.Equals("YES"))
                return "bool?";
            else if ((type.Equals("decimal") || type.Equals("numeric") || type.Equals("float") || type.Equals("real")) && nullAble.Equals("NO"))
                return "decimal";
            else if ((type.Equals("decimal") || type.Equals("numeric") || type.Equals("float") || type.Equals("real")) && nullAble.Equals("YES"))
                return "decimal?";
            else if (type.Equals("datetime") && nullAble.Equals("YES"))
                return "DateTime?";
            else if (type.Equals("datetime") && nullAble.Equals("NO"))
                return "DateTime";
            else if (type.Equals("nchar") || type.Equals("char") || type.Equals("nvarchar") || type.Equals("varchar") || type.Equals("text"))
                return "string";
            else throw new Exception("无此类型");
        }
    }
}