apewer-dotnet/Apewer/Source/Sqlite.cs

#if EXTRA

/* 2021.08.03 */

using Apewer;
using Apewer.Source;
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SQLite;
using System.Text;
using System.Data.Common;
//using Mono.Data.Sqlite;

namespace Apewer.Source
{

    /// <summary>用于快速连接 SQLite 数据库的辅助。</summary>
    public class Sqlite : IDatabase, IOrm, IDisposable
    {

        #region 变量定义。

        private SQLiteConnection _db = null;

        private Timeout _timeout = new Timeout();
        private string _connstring = "";
        private string _path = "";
        private string _pass = "";
        private byte[] _passdata = BinaryUtility.EmptyBytes;

        #endregion

        #region this

        private void VarInit(string path, Timeout timeout, string pass, byte[] passData)
        {
            _path = (path == null) ? "" : path;
            _passdata = (passData == null) ? BinaryUtility.EmptyBytes : passData;
            _pass = (pass == null) ? "" : pass;
            _timeout = timeout;
        }

        /// <summary>连接内存。</summary>
        public Sqlite() => VarInit(Memory, new Timeout(), null, null);

        /// <summary>连接指定文件。</summary>
        public Sqlite(string path) => VarInit(path, new Timeout(), null, null);

        /// <summary>连接指定文件。</summary>
        private Sqlite(string path, byte[] passData) => VarInit(path, new Timeout(), null, passData);

        /// <summary>连接指定文件。</summary>
        public Sqlite(string path, string pass) => VarInit(path, new Timeout(), pass, null);

        /// <summary>连接指定文件。</summary>
        public Sqlite(string path, Timeout timeout) => VarInit(path, timeout, null, null);

        /// <summary>连接指定文件。</summary>
        private Sqlite(string path, Timeout timeout, byte[] pass) => VarInit(path, timeout, null, pass);

        /// <summary>连接指定文件。</summary>
        public Sqlite(string path, Timeout timeout, string pass) => VarInit(path, timeout, pass, null);

        #endregion

        #region 日志。

        /// <summary>获取或设置日志记录。</summary>
        public Logger Logger { get; set; }

        private void LogError(string action, Exception ex, string addtion)
        {
            var logger = Logger;
            if (logger != null) logger.Error(this, "SQLite", action, ex.GetType().FullName, ex.Message, addtion);
        }

        private void LogError(string action, string message)
        {
            var logger = Logger;
            if (logger != null) logger.Error(this, "SQLite", action, message);
        }

        #endregion

        #region 实现接口。

        /// <summary>数据库是否已经连接。</summary>
        public bool Online { get => _db != null && _db.State == ConnectionState.Open; }

        /// <summary>连接数据库，若未连接则尝试连接。</summary>
        /// <returns>是否已连接。</returns>
        public bool Connect()
        {
            if (_db == null)
            {
                _db = new SQLiteConnection();
                _db.ConnectionString = ConnectionString;
                //if (string.IsNullOrEmpty(_connstring) && string.IsNullOrEmpty(_pass) && (_passdata.Length > 0))
                //{
                //    _db.SetPassword(_pass);
                //}
            }
            else
            {
                if (_db.State == ConnectionState.Open) return true;
            }
            try
            {
                _db.Open();
                switch (_db.State)
                {
                    case ConnectionState.Open: return true;
                    default: return false;
                }
            }
            catch (Exception ex)
            {
                LogError("Connection", ex, _db.ConnectionString);
                Close();
                return false;
            }
        }

        /// <summary>关闭连接，并释放对象所占用的系统资源。</summary>
        public void Close()
        {
            if (_db != null)
            {
                //_db.Close();
                _db.Dispose();
                _db = null;
            }
        }

        /// <summary>关闭连接，释放对象所占用的系统资源，并清除连接信息。</summary>
        public void Dispose() { Close(); }

        /// <summary>查询。</summary>
        public IQuery Query(string sql) => Query(sql, null);

        /// <summary>查询。</summary>
        public IQuery Query(string sql, IEnumerable<IDataParameter> parameters)
        {
            if (string.IsNullOrEmpty(sql)) return Example.InvalidQueryStatement;

            const string table = "result";

            var connected = Connect();
            if (!connected) return Example.InvalidQueryConnection;

            var query = new Query();
            try
            {
                var command = new SQLiteCommand();
                command.Connection = _db;
                command.CommandTimeout = Timeout.Query;
                command.CommandText = sql;
                if (parameters != null)
                {
                    foreach (var p in parameters)
                    {
                        if (p != null) command.Parameters.Add(p);
                    }
                }
                using (var dataset = new DataSet())
                {
                    using (var da = new SQLiteDataAdapter(sql, _db))
                    {
                        da.Fill(dataset, table);
                        query.Table = dataset.Tables[table];
                    }
                }
                command.Dispose();
                query.Success = true;
            }
            catch (Exception ex)
            {
                LogError("Query", ex, sql);
                query.Success = false;
                query.Exception = ex;
            }
            return query;
        }

        /// <summary>执行单条 Transact-SQL 语句。</summary>
        public IExecute Execute(string sql) => Execute(sql, null);

        /// <summary>执行单条 Transact-SQL 语句，并加入参数。</summary>
        public IExecute Execute(string sql, IEnumerable<IDataParameter> parameters)
        {
            if (string.IsNullOrEmpty(sql)) return Example.InvalidExecuteStatement;

            var connected = Connect();
            if (!connected) return Example.InvalidExecuteConnection;

            var transaction = _db.BeginTransaction();
            var execute = new Execute();
            try
            {
                var command = new SQLiteCommand();
                command.Connection = _db;
                command.Transaction = transaction;
                command.CommandTimeout = Timeout.Execute;
                command.CommandText = sql;
                if (parameters != null)
                {
                    foreach (var p in parameters)
                    {
                        if (p != null) command.Parameters.Add(p);
                    }
                }
                execute.Rows += command.ExecuteNonQuery();
                transaction.Commit();
                command.Dispose();
                execute.Success = true;
            }
            catch (Exception ex)
            {
                try { transaction.Rollback(); } catch { }
                LogError("Execute", ex, sql);
                execute.Success = false;
                execute.Exception = ex;
            }
            try { transaction.Dispose(); } catch { }
            return execute;
        }

        #endregion

        #region 属性。

        /// <summary>获取当前的 SQLiteConnection 对象。</summary>
        public IDbConnection Connection { get => _db; }

        /// <summary>获取或设置超时。</summary>
        public Timeout Timeout { get => _timeout; set => _timeout = value; }

        /// <summary>获取或设置连接字符串，连接字符串非空时将忽略 Path 属性。数据库在线时无法设置。</summary>
        public string ConnectionString
        {
            get
            {
                if (string.IsNullOrEmpty(_connstring))
                {
                    var temp = new StringBuilder();
                    temp.Append("data source='", _path, "'; version=3; ");
                    if (!string.IsNullOrEmpty(_pass)) temp.Append("password=", _pass, "; ");
                    return temp.ToString();
                }
                else return _connstring;
            }
            set
            {
                if (Online) return;
                _connstring = string.IsNullOrEmpty(value) ? "" : value;
            }
        }

        /// <summary>获取或设置数据库路径（文件或内存）。数据库在线时无法设置。</summary>
        public string Path
        {
            get { return _path; }
            set
            {
                if (Online) return;
                _path = string.IsNullOrEmpty(value) ? "" : value;
            }
        }

        /// <summary>获取或设置数据库密码。数据库在线时无法设置。</summary>
        public string Password
        {
            get { return _pass; }
            set
            {
                if (Online) return;
                _pass = string.IsNullOrEmpty(value) ? "" : value;
            }
        }

        /// <summary>获取或设置数据库密码。数据库在线时无法设置。</summary>
        private byte[] PasswordData
        {
            get { return _passdata; }
            set
            {
                if (Online) return;
                _passdata = (value == null) ? BinaryUtility.EmptyBytes : value;
            }
        }

        /// <summary>保存当前数据库到文件，若文件已存在则将重写文件。</summary>
        public bool Save(string path)
        {
            if (!StorageUtility.CreateFile(path, 0, true))
            {
                LogError("Save", TextUtility.Merge("创建文件 ", path, " 失败。"));
                return false;
            }

            var temp = new Sqlite(path);
            var result = Save(temp);
            temp.Close();
            return result;
        }

        /// <summary>保存当前数据库到文件，若文件已存在则将重写文件。</summary>
        public bool Save(string path, string password)
        {
            if (!StorageUtility.CreateFile(path, 0, true))
            {
                LogError("Save", TextUtility.Merge("创建文件 ", path, " 失败。"));
                return false;
            }

            var temp = new Sqlite(path, password);
            var result = Save(temp);
            temp.Close();
            return result;
        }

        /// <summary>保存当前数据库到目标数据库。</summary>
        public bool Save(Sqlite destination)
        {
            var error = Backup(this, destination);
            return string.IsNullOrEmpty(error);
        }

        /// <summary>加载文件到当前数据库。</summary>
        public bool Load(string path)
        {
            var temp = new Sqlite(path);
            var result = Load(temp);
            temp.Close();
            return result;
        }

        /// <summary>加载文件到当前数据库。</summary>
        public bool Load(string path, params byte[] pass)
        {
            var temp = new Sqlite(path, pass);
            var result = Load(temp);
            temp.Close();
            return result;
        }

        /// <summary>加载文件到当前数据库。</summary>
        public bool Load(string path, string pass)
        {
            var temp = new Sqlite(path, pass);
            var result = Load(temp);
            temp.Close();
            return result;
        }

        /// <summary>加载源数据库到当前数据库。</summary>
        public bool Load(Sqlite source)
        {
            var error = Backup(source, this);
            return string.IsNullOrEmpty(error);
        }

        #endregion

        #region ORM。

        /// <summary>查询数据库中的所有表名。</summary>
        public List<string> TableNames()
        {
            var list = new List<string>();
            if (Connect())
            {
                var sql = "select name from sqlite_master where type='table' order by name; ";
                var query = (Query)Query(sql);
                for (int r = 0; r < query.Rows; r++)
                {
                    var cell = query.Text(r, 0);
                    if (TextUtility.IsBlank(cell)) continue;
                    list.Add(cell);
                }
                query.Dispose();
            }
            return list;
        }

        /// <summary>查询数据库中的所有视图名。</summary>
        public List<string> ViewNames()
        {
            var list = new List<string>();
            if (Connect())
            {
                var sql = "select name from sqlite_master where type='view' order by name; ";
                var query = (Query)Query(sql);
                for (int r = 0; r < query.Rows; r++)
                {
                    var cell = query.Text(r, 0);
                    if (TextUtility.IsBlank(cell)) continue;
                    list.Add(cell);
                }
                query.Dispose();
            }
            return list;
        }

        /// <summary>查询表中的所有列名。</summary>
        public List<string> ColumnNames(string table)
        {
            var list = new List<string>();
            if (Connect())
            {
                var t = TextUtility.AntiInject(table);
                var sql = TextUtility.Merge("pragma table_info('", TextUtility.AntiInject(t), "'); ");
                using (var query = Query(sql) as Query)
                {
                    for (int r = 0; r < query.Rows; r++)
                    {
                        var cell = query.Text(r, "name");
                        if (TextUtility.IsBlank(cell)) continue;
                        list.Add(cell);
                    }
                }
            }
            return list;
        }

        /// <summary>创建表，不修改已存在表。成功时返回空字符串，发生异常时返回异常信息。</summary>
        public string Initialize(Record model) => model == null ? "参数无效。" : Initialize(model.GetType());

        /// <summary>创建表，不修改已存在表。成功时返回空字符串，发生异常时返回异常信息。</summary>
        public string Initialize<T>() where T : Record => Initialize(typeof(T));

        /// <summary>创建表，不修改已存在表。当现存表中缺少模型中属性对应的列时增加列。成功时返回空字符串，发生异常时返回异常信息。</summary>
        public string Initialize(Type model)
        {
            var structure = null as TableStructure;
            try { structure = TableStructure.ParseModel(model); }
            catch (Exception exception) { return exception.Message; }

            // 连接数据库。
            if (!Connect()) return "连接数据库失败。";

            // 检查现存表。
            var exists = false;
            var tables = TableNames();
            if (tables.Count > 0)
            {
                var lower = structure.Table.ToLower();
                foreach (var table in tables)
                {
                    if (TextUtility.IsBlank(table)) continue;
                    if (table.ToLower() == lower)
                    {
                        exists = true;
                        break;
                    }
                }
            }

            if (exists)
            {
                return TextUtility.Merge("指定的表已经存在。");
            }
            else
            {
                var sqlcolumns = new List<string>();
                foreach (var column in structure.Columns.Values)
                {
                    var type = GetColumnDeclaration(column);
                    if (type == TextUtility.EmptyString) return TextUtility.Merge("类型 ", column.Type.ToString(), " 不受支持。");
                    sqlcolumns.Add(type);
                }
                var sql = TextUtility.Merge("create table [", structure.Table, "](", TextUtility.Join(", ", sqlcolumns), "); ");
                var execute = Execute(sql);
                if (execute.Success) return TextUtility.EmptyString;
                return execute.Error;
            }
        }

        /// <summary>插入记录。成功时候返回空字符串，发生异常时返回异常信息。</summary>
        public string Insert(Record record)
        {
            if (record == null) return "参数无效。";
            record.FixProperties();

            var structure = null as TableStructure;
            try { structure = TableStructure.ParseModel(record); }
            catch (Exception exception) { return exception.Message; }

            var parameters = structure.CreateDataParameters(record, CreateDataParameter);

            var sql = GenerateInsertStatement(structure.Table, (IEnumerable<IDataParameter>)parameters);

            var execute = Execute(sql, parameters);
            if (execute.Success && execute.Rows > 0) return TextUtility.EmptyString;
            return execute.Error;
        }

        /// <summary>更新记录，实体中的 Created 和 Key 属性不被更新。成功时返回空字符串，发生异常时返回异常信息。</summary>
        public string Update(Record record)
        {
            if (record == null) return "参数无效。";
            record.FixProperties();
            record.Updated = ClockUtility.LucidNow;

            var structure = null as TableStructure;
            try { structure = TableStructure.ParseModel(record); }
            catch (Exception exception) { return exception.Message; }

            var parameters = structure.CreateDataParameters(record, CreateDataParameter, "_created", "_key");

            var sql = GenerateUpdateStatement(structure.Table, record.Key, parameters);

            var execute = Execute(sql, parameters);
            if (execute.Success && execute.Rows > 0) return TextUtility.EmptyString;
            return execute.Error;
        }

        /// <summary>获取具有指定 Key 的记录。</summary>
        public Result<T> Get<T>(string key) where T : Record => Get<T>(key, 0);

        /// <summary>获取具有指定 Key 的记录。</summary>
        public Result<T> Get<T>(string key, long flag) where T : Record
        {
            var k = TextUtility.SafeKey(key);
            if (TextUtility.IsBlank(k) == false)
            {
                try
                {
                    var ts = TableStructure.ParseModel(typeof(T));
                    var f = (flag == 0) ? TextUtility.EmptyString : TextUtility.Merge(" _flag=", flag.ToString(), " and");
                    var query = (Query)Query(TextUtility.Merge("select * from [", ts.Table, "] where", f, " _key='", k, "' limit 1; "));
                    var list = query.Fill<T>();
                    query.Dispose();
                    if (list.Count > 0) return new Result<T>(list[0]);
                }
                catch (Exception ex)
                {
                    return new Result<T>(ex);
                }
            }
            return new Result<T>(new Exception("参数无效。"));
        }

        /// <summary>查询多条记录。</summary>
        public Result<List<T>> Query<T>() where T : Record => Query<T>(0);

        /// <summary>查询多条记录。</summary>
        public Result<List<T>> Query<T>(long flag) where T : Record
        {
            try
            {
                var ts = TableStructure.ParseModel(typeof(T));
                var f = (flag == 0) ? TextUtility.EmptyString : TextUtility.Merge(" where _flag=", flag.ToString());
                var query = Query(TextUtility.Merge("select * from [", ts.Table, "]", f, "; ")) as Query;
                var list = query.Fill<T>();
                query.Dispose();
                return new Result<List<T>>(list);
            }
            catch (Exception ex)
            {
                return new Result<List<T>>(ex);
            }
        }

        /// <summary>获取按指定语句查询到的所有记录。</summary>
        public Result<List<T>> Query<T>(string sql) where T : Record
        {
            using (var query = Query(sql) as Query)
            {
                if (query.Exception == null) return new Result<List<T>>(query.Fill<T>());
                else return new Result<List<T>>(query.Exception);
            }
        }

        /// <summary>查询所有有效的 Key 值。</summary>
        public Result<List<string>> Keys<T>() where T : Record => Keys<T>(0);

        /// <summary>查询所有有效的 Key 值。</summary>
        public Result<List<string>> Keys<T>(long flag) where T : Record => Keys(typeof(T), flag);

        /// <summary>查询所有有效的 Key 值。</summary>
        public Result<List<string>> Keys(Type model) => Keys(model, 0);

        /// <summary>查询所有有效的 Key 值。</summary>
        public Result<List<string>> Keys(Type model, long flag)
        {
            if (model != null)
            {
                try
                {
                    var list = new List<string>();
                    var ts = TableStructure.ParseModel((Type)model);
                    var f = (flag == 0) ? TextUtility.EmptyString : TextUtility.Merge(" where _flag=", flag.ToString());
                    var query = (Query)Query(TextUtility.Merge("select _key from [", ts.Table, "]", f, "; "));
                    for (var r = 0; r < query.Rows; r++)
                    {
                        var cell = TextUtility.Trim(query.Text(r));
                        if (cell.Length > 0) list.Add(cell);
                    }
                    query.Dispose();
                    return new Result<List<string>>(list);
                }
                catch (Exception ex)
                {
                    return new Result<List<string>>(ex);
                }
            }
            return new Result<List<string>>(new Exception("参数无效。"));
        }

        #endregion

        #region static

        /// <summary>对文本转义，符合 SQL 安全性。可根据字段类型限制 UTF-8 字节数，默认为 0 时不限制字节数。</summary>
        public static string Escape(string text, int bytes = 0)
        {
            if (text.IsEmpty()) return "";

            var t = text ?? "";
            t = t.Replace("\\", "\\\\");
            t = t.Replace("'", "\\'");
            t = t.Replace("\n", "\\n");
            t = t.Replace("\r", "\\r");
            t = t.Replace("\b", "\\b");
            t = t.Replace("\t", "\\t");
            t = t.Replace("\f", "\\f");

            if (bytes > 5)
            {
                if (t.GetBytes(Encoding.UTF8).Length > bytes)
                {
                    while (true)
                    {
                        t = t.Substring(0, t.Length - 1);
                        if (t.GetBytes(Encoding.UTF8).Length <= (bytes - 4)) break;
                    }
                    t = t + " ...";
                }
            }

            return t;
        }

        private static string GetColumnTypeName(ColumnType type)
        {
            switch (type)
            {
                case ColumnType.Binary:
                    return "blob";
                case ColumnType.Integer:
                    return "integer";
                case ColumnType.Float:
                    return "float";
                case ColumnType.VarChar:
                case ColumnType.VarChar255:
                case ColumnType.VarCharMax:
                    return "varchar";
                case ColumnType.Text:
                    return "text";
                case ColumnType.NVarChar:
                case ColumnType.NVarChar255:
                case ColumnType.NVarCharMax:
                    return "nvarchar";
                case ColumnType.NText:
                    return "ntext";
                default:
                    return null;
            }
        }

        private static string GetColumnDeclaration(ColumnAttribute column)
        {
            var type = TextUtility.EmptyString;
            var length = NumberUtility.RestrictValue(column.Length, 0, 255).ToString();
            switch (column.Type)
            {
                case ColumnType.Binary:
                    type = "blob";
                    break;
                case ColumnType.Integer:
                    type = "integer";
                    break;
                case ColumnType.Float:
                    type = "real";
                    break;
                case ColumnType.VarChar:
                case ColumnType.VarChar255:
                    type = TextUtility.Merge("varchar(", length, ")");
                    break;
                case ColumnType.VarCharMax:
                    type = TextUtility.Merge("varchar(255)");
                    break;
                case ColumnType.Text:
                    type = TextUtility.Merge("text");
                    break;
                case ColumnType.NVarChar:
                case ColumnType.NVarChar255:
                    type = TextUtility.Merge("nvarchar(", length, ")");
                    break;
                case ColumnType.NVarCharMax:
                    type = TextUtility.Merge("nvarchar(255)");
                    break;
                case ColumnType.NText:
                    type = TextUtility.Merge("ntext");
                    break;
                default:
                    return TextUtility.EmptyString;
            }
            return TextUtility.Merge("[", (object)column.Field, "] ", type);
        }

        /// <summary>创建参数。</summary>
        /// <exception cref="ArgumentNullException"></exception>
        /// <exception cref="InvalidOperationException"></exception>
        public static SQLiteParameter CreateDataParameter(Parameter parameter)
        {
            if (parameter == null) throw new InvalidOperationException("参数无效。");
            return CreateDataParameter(parameter.Name, parameter.Type, parameter.Size, parameter.Value);
        }

        /// <summary>创建参数。</summary>
        public static SQLiteParameter CreateDataParameter(string name, ColumnType type, int size, object value)
        {
            var n = TextUtility.Trim(name);
            if (TextUtility.IsBlank(n)) return null;

            var t = GetColumnTypeName(type);

            var s = size;
            switch (type)
            {
                case ColumnType.VarChar:
                    s = NumberUtility.RestrictValue(s, 0, 8000);
                    break;
                case ColumnType.NVarChar:
                    s = NumberUtility.RestrictValue(s, 0, 4000);
                    break;
                case ColumnType.VarChar255:
                case ColumnType.VarCharMax:
                case ColumnType.NVarChar255:
                case ColumnType.NVarCharMax:
                    s = NumberUtility.RestrictValue(s, 0, 255);
                    break;
                default:
                    s = 0;
                    break;
            }

            var v = value;
            if (v is string && v != null && s > 0)
            {
                v = TextUtility.RestrictLength((string)v, s);
            }

            var p = new SQLiteParameter();
            p.ParameterName = n;
            p.TypeName = t;
            p.Value = v;
            if (s > 0) p.Size = s;
            return p;
        }

        /// <summary>创建参数。</summary>
        public static SQLiteParameter CreateDataParameter(string name, string type, int size, object value)
        {
            var v = value;
            if (value is string && value != null && size > 0)
            {
                v = TextUtility.RestrictLength((string)value, size);
            }

            var p = new SQLiteParameter();
            p.ParameterName = name;
            p.TypeName = type;
            p.Value = v;
            p.Size = size;
            return p;
        }

        /// <summary>创建参数。</summary>
        public static SQLiteParameter CreateDataParameter(string name, string type, object value)
        {
            var p = new SQLiteParameter();
            p.ParameterName = name;
            p.TypeName = type;
            p.Value = value;
            return p;
        }

        /// <summary>备份数据库，返回错误信息。</summary>
        public static string Backup(Sqlite source, Sqlite destination)
        {
            if (source == null) return "SQLite Backup Failed: Invalid Source";
            if (destination == null) return "SQLite Backup Failed: Invalid Destination";
            if (!source.Connect()) return "SQLite Backup Failed: Invalid Source Connection";
            if (!destination.Connect()) return "SQLite Backup Failed: Invalid Destination Connection";

            try
            {
                source._db.BackupDatabase(destination._db, "main", "main", -1, null, 0);
                return "";
            }
            catch (Exception ex)
            {
                return "SQLite Load Failed: " + ex.Message;
            }
        }

        /// <summary>创建参数。</summary>
        public static IDbDataParameter CreateParameter(string field, DbType type, int size, object value)
        {
            var p = new SQLiteParameter();
            p.ParameterName = field;
            p.DbType = type;
            p.Size = size;
            p.Value = value;
            return p;
        }

        /// <summary>创建参数。</summary>
        public static IDbDataParameter CreateParameter(string field, DbType type, object value)
        {
            var p = new SQLiteParameter();
            p.ParameterName = field;
            p.DbType = type;
            p.Value = value;
            return p;
        }

        /// <summary>整理数据库，压缩未使用的空间。</summary>
        public const string Vacuum = "vacuum";

        /// <summary>内存数据库的地址。</summary>
        public const string Memory = ":memory:";

        #endregion

        #region ORM

        private static string GetParameterName(string parameter)
        {
            var name = TextUtility.AntiInject(parameter, 255);
            if (name.StartsWith("@") && name.Length > 1)
            {
                name = name.Substring(1, name.Length - 1);
            }
            return name;
        }

        private static string GetParameterName(IDataParameter parameter)
        {
            var name = TextUtility.EmptyString;
            if (parameter != null)
            {
                name = GetParameterName(parameter.ParameterName);
            }
            return name;
        }

        private static List<string> GetParametersNames(IEnumerable<IDataParameter> parameters)
        {
            var columns = new List<string>();
            if (parameters != null)
            {
                foreach (var parameter in parameters)
                {
                    var name = GetParameterName(parameter);
                    var isblank = TextUtility.IsBlank(name);
                    if (isblank) continue;
                    columns.Add(name);
                }
            }
            return columns;
        }

        private static string GenerateInsertStatement(string table, List<string> columns)
        {
            var r = TextUtility.EmptyString;
            var t = TextUtility.AntiInject(table, 255);
            if (columns != null && !TextUtility.IsBlank(t))
            {
                var count = 0;
                var names = new List<string>();
                var values = new List<string>();
                foreach (var column in columns)
                {
                    //names.Add(TextGenerator.Merge("[", column, "]"));
                    names.Add(TextUtility.Merge(column));
                    values.Add("@" + column);
                    count += 1;
                }
                var sb = new StringBuilder();
                if (count > 0)
                {
                    sb.Append("insert into [", t, "](", TextUtility.Join(", ", names), ") ");
                    sb.Append("values(", TextUtility.Join(", ", values), "); ");
                }
                r = sb.ToString();
            }
            return r;
        }

        /// <summary>生成 INSERT INTO 语句。表名必须有效，无有效参数时将获取空结果。</summary>
        /// <exception cref="System.ArgumentException"></exception>
        /// <exception cref="System.ArgumentNullException"></exception>
        public static string GenerateInsertStatement(string table, IEnumerable<IDataParameter> parameters)
        {
            if (table == null) throw new ArgumentNullException(nameof(table));
            var t = TextUtility.AntiInject(table, 255);
            if (TextUtility.IsBlank(t)) throw new ArgumentException("表名无效。", nameof(table));

            var cs = GetParametersNames(parameters);
            if (cs.Count < 1) return TextUtility.EmptyString;

            return GenerateInsertStatement(t, cs);
        }

        private static string GenerateUpdateStatement(string table, string key, List<string> columns)
        {
            var result = TextUtility.EmptyString;
            var t = TextUtility.AntiInject(table, 255);
            var k = TextUtility.AntiInject(key, 255);
            if (columns != null && !TextUtility.IsBlank(t) && !TextUtility.IsBlank(k))
            {
                var items = new List<string>();
                foreach (var column in columns)
                {
                    items.Add(TextUtility.Merge("[", column, "]=@", column));
                }
                if (items.Count > 0)
                {
                    result = TextUtility.Merge("update [", t, "] set ", TextUtility.Join(", ", items), " where [_key]='", k, "'; ");
                }
            }
            return result;
        }

        /// <summary>生成 UPDATE 语句，键字段名为“_key”。表名必须有效，键值必须有效，无有效参数时将获取空结果。</summary>
        /// <exception cref="System.ArgumentException"></exception>
        /// <exception cref="System.ArgumentNullException"></exception>
        public static string GenerateUpdateStatement(string table, string key, IEnumerable<IDataParameter> parameters)
        {
            if (table == null) throw new ArgumentNullException("argTable");
            var t = TextUtility.AntiInject(table, 255);
            if (TextUtility.IsBlank(t)) throw new ArgumentException("表名无效。", nameof(table));

            if (key == null) throw new ArgumentNullException("argKey");
            var k = TextUtility.AntiInject(key, 255);
            if (TextUtility.IsBlank(k)) throw new ArgumentException("键值无效。", nameof(key));

            var columns = GetParametersNames(parameters);
            if (columns.Count < 1) return TextUtility.EmptyString;

            return GenerateUpdateStatement(t, k, columns);
        }

        #endregion

    }

}

#endif