System.Data.DataTableReader.GetSchemaTableFromDataTable C# (CSharp) Метод

        internal static DataTable GetSchemaTableFromDataTable(DataTable table)
        {
            if (table == null)
            {
                throw ExceptionBuilder.ArgumentNull(nameof(DataTable));
            }

            DataTable tempSchemaTable = new DataTable("SchemaTable");
            tempSchemaTable.Locale = System.Globalization.CultureInfo.InvariantCulture;

            DataColumn ColumnName = new DataColumn(SchemaTableColumn.ColumnName, typeof(string));
            DataColumn ColumnOrdinal = new DataColumn(SchemaTableColumn.ColumnOrdinal, typeof(int));
            DataColumn ColumnSize = new DataColumn(SchemaTableColumn.ColumnSize, typeof(int));
            DataColumn NumericPrecision = new DataColumn(SchemaTableColumn.NumericPrecision, typeof(short));
            DataColumn NumericScale = new DataColumn(SchemaTableColumn.NumericScale, typeof(short));
            DataColumn DataType = new DataColumn(SchemaTableColumn.DataType, typeof(Type));
            DataColumn ProviderType = new DataColumn(SchemaTableColumn.ProviderType, typeof(int));
            DataColumn IsLong = new DataColumn(SchemaTableColumn.IsLong, typeof(bool));
            DataColumn AllowDBNull = new DataColumn(SchemaTableColumn.AllowDBNull, typeof(bool));
            DataColumn IsReadOnly = new DataColumn(SchemaTableOptionalColumn.IsReadOnly, typeof(bool));
            DataColumn IsRowVersion = new DataColumn(SchemaTableOptionalColumn.IsRowVersion, typeof(bool));
            DataColumn IsUnique = new DataColumn(SchemaTableColumn.IsUnique, typeof(bool));
            DataColumn IsKeyColumn = new DataColumn(SchemaTableColumn.IsKey, typeof(bool));
            DataColumn IsAutoIncrement = new DataColumn(SchemaTableOptionalColumn.IsAutoIncrement, typeof(bool));
            DataColumn BaseSchemaName = new DataColumn(SchemaTableColumn.BaseSchemaName, typeof(string));
            DataColumn BaseCatalogName = new DataColumn(SchemaTableOptionalColumn.BaseCatalogName, typeof(string));
            DataColumn BaseTableName = new DataColumn(SchemaTableColumn.BaseTableName, typeof(string));
            DataColumn BaseColumnName = new DataColumn(SchemaTableColumn.BaseColumnName, typeof(string));
            DataColumn AutoIncrementSeed = new DataColumn(SchemaTableOptionalColumn.AutoIncrementSeed, typeof(long));
            DataColumn AutoIncrementStep = new DataColumn(SchemaTableOptionalColumn.AutoIncrementStep, typeof(long));
            DataColumn DefaultValue = new DataColumn(SchemaTableOptionalColumn.DefaultValue, typeof(object));
            DataColumn Expression = new DataColumn(SchemaTableOptionalColumn.Expression, typeof(string));
            DataColumn ColumnMapping = new DataColumn(SchemaTableOptionalColumn.ColumnMapping, typeof(MappingType));
            DataColumn BaseTableNamespace = new DataColumn(SchemaTableOptionalColumn.BaseTableNamespace, typeof(string));
            DataColumn BaseColumnNamespace = new DataColumn(SchemaTableOptionalColumn.BaseColumnNamespace, typeof(string));

            ColumnSize.DefaultValue = -1;

            if (table.DataSet != null)
            {
                BaseCatalogName.DefaultValue = table.DataSet.DataSetName;
            }

            BaseTableName.DefaultValue = table.TableName;
            BaseTableNamespace.DefaultValue = table.Namespace;
            IsRowVersion.DefaultValue = false;
            IsLong.DefaultValue = false;
            IsReadOnly.DefaultValue = false;
            IsKeyColumn.DefaultValue = false;
            IsAutoIncrement.DefaultValue = false;
            AutoIncrementSeed.DefaultValue = 0;
            AutoIncrementStep.DefaultValue = 1;

            tempSchemaTable.Columns.Add(ColumnName);
            tempSchemaTable.Columns.Add(ColumnOrdinal);
            tempSchemaTable.Columns.Add(ColumnSize);
            tempSchemaTable.Columns.Add(NumericPrecision);
            tempSchemaTable.Columns.Add(NumericScale);
            tempSchemaTable.Columns.Add(DataType);
            tempSchemaTable.Columns.Add(ProviderType);
            tempSchemaTable.Columns.Add(IsLong);
            tempSchemaTable.Columns.Add(AllowDBNull);
            tempSchemaTable.Columns.Add(IsReadOnly);
            tempSchemaTable.Columns.Add(IsRowVersion);
            tempSchemaTable.Columns.Add(IsUnique);
            tempSchemaTable.Columns.Add(IsKeyColumn);
            tempSchemaTable.Columns.Add(IsAutoIncrement);
            tempSchemaTable.Columns.Add(BaseCatalogName);
            tempSchemaTable.Columns.Add(BaseSchemaName);

            // specific to datatablereader
            tempSchemaTable.Columns.Add(BaseTableName);
            tempSchemaTable.Columns.Add(BaseColumnName);
            tempSchemaTable.Columns.Add(AutoIncrementSeed);
            tempSchemaTable.Columns.Add(AutoIncrementStep);
            tempSchemaTable.Columns.Add(DefaultValue);
            tempSchemaTable.Columns.Add(Expression);
            tempSchemaTable.Columns.Add(ColumnMapping);
            tempSchemaTable.Columns.Add(BaseTableNamespace);
            tempSchemaTable.Columns.Add(BaseColumnNamespace);

            foreach (DataColumn dc in table.Columns)
            {
                DataRow dr = tempSchemaTable.NewRow();

                dr[ColumnName] = dc.ColumnName;
                dr[ColumnOrdinal] = dc.Ordinal;
                dr[DataType] = dc.DataType;

                if (dc.DataType == typeof(string))
                {
                    dr[ColumnSize] = dc.MaxLength;
                }

                dr[AllowDBNull] = dc.AllowDBNull;
                dr[IsReadOnly] = dc.ReadOnly;
                dr[IsUnique] = dc.Unique;

                if (dc.AutoIncrement)
                {
                    dr[IsAutoIncrement] = true;
                    dr[AutoIncrementSeed] = dc.AutoIncrementSeed;
                    dr[AutoIncrementStep] = dc.AutoIncrementStep;
                }

                if (dc.DefaultValue != DBNull.Value)
                {
                    dr[DefaultValue] = dc.DefaultValue;
                }

                if (dc.Expression.Length != 0)
                {
                    bool hasExternalDependency = false;
                    DataColumn[] dependency = dc.DataExpression.GetDependency();
                    for (int j = 0; j < dependency.Length; j++)
                    {
                        if (dependency[j].Table != table)
                        {
                            hasExternalDependency = true;
                            break;
                        }
                    }
                    if (!hasExternalDependency)
                    {
                        dr[Expression] = dc.Expression;
                    }
                }

                dr[ColumnMapping] = dc.ColumnMapping;
                dr[BaseColumnName] = dc.ColumnName;
                dr[BaseColumnNamespace] = dc.Namespace;

                tempSchemaTable.Rows.Add(dr);
            }

            foreach (DataColumn key in table.PrimaryKey)
            {
                tempSchemaTable.Rows[key.Ordinal][IsKeyColumn] = true;
            }

            tempSchemaTable.AcceptChanges();

            return tempSchemaTable;
        }