/// <summary>
 ///     创建SQL
 /// </summary>
 /// <param name="expression">委托关联表达式</param>
 /// <returns>SQL表达式</returns>
 internal unsafe string Create(TmphLambdaExpression expression)
 {
     var TmphBuffer = TmphClient.SqlBuffers.Get();
     try
     {
         using (stream = new TmphCharStream(TmphBuffer.Char, TmphClient.SqlBufferSize))
         {
             create(expression, stream);
             return stream.ToString();
         }
     }
     finally
     {
         TmphClient.SqlBuffers.Push(ref TmphBuffer);
     }
 }
 /// <summary>
 ///     创建SQL
 /// </summary>
 /// <param name="expression">委托关联表达式</param>
 /// <param name="sqlStream">SQL表达式流</param>
 protected abstract void create(TmphLambdaExpression expression, TmphCharStream stream);