System.Data.Common.DbCommandBuilder.BuildWhereClause C# (CSharp) Method

        private int BuildWhereClause(
            DataTableMapping mappings,
            DataRow dataRow,
            StringBuilder builder,
            DbCommand command,
            int parameterCount,
            bool isUpdate
            )
        {
            string beginNewCondition = string.Empty;
            int whereCount = 0;

            builder.Append(Where);
            builder.Append(LeftParenthesis);

            DbSchemaRow[] schemaRows = _dbSchemaRows;
            for (int i = 0; i < schemaRows.Length; ++i)
            {
                DbSchemaRow row = schemaRows[i];

                if ((null == row) || (0 == row.BaseColumnName.Length) || !IncludeInWhereClause(row, isUpdate))
                {
                    continue;
                }
                builder.Append(beginNewCondition);
                beginNewCondition = And;

                object value = null;
                string sourceColumn = _sourceColumnNames[i];
                string baseColumnName = QuotedColumn(row.BaseColumnName);

                if ((null != mappings) && (null != dataRow))
                    value = GetColumnValue(dataRow, sourceColumn, mappings, DataRowVersion.Original);

                if (!row.AllowDBNull)
                {
                    //  (<baseColumnName> = ?)
                    builder.Append(LeftParenthesis);
                    builder.Append(baseColumnName);
                    builder.Append(Equal);
                    builder.Append(
                        CreateParameterForValue(
                            command,
                            GetOriginalParameterName(i),
                            sourceColumn,
                            DataRowVersion.Original,
                            parameterCount,
                            value,
                            row, (isUpdate ? StatementType.Update : StatementType.Delete), true
                        )
                    );
                    parameterCount++;
                    builder.Append(RightParenthesis);
                }
                else
                {
                    //  ((? = 1 AND <baseColumnName> IS NULL) OR (<baseColumnName> = ?))
                    builder.Append(LeftParenthesis);

                    builder.Append(LeftParenthesis);
                    builder.Append(
                        CreateParameterForNullTest(
                            command,
                            GetNullParameterName(i),
                            sourceColumn,
                            DataRowVersion.Original,
                            parameterCount,
                            value,
                            row, (isUpdate ? StatementType.Update : StatementType.Delete), true
                        )
                    );
                    parameterCount++;
                    builder.Append(EqualOne);
                    builder.Append(And);
                    builder.Append(baseColumnName);
                    builder.Append(IsNull);
                    builder.Append(RightParenthesis);

                    builder.Append(Or);

                    builder.Append(LeftParenthesis);
                    builder.Append(baseColumnName);
                    builder.Append(Equal);
                    builder.Append(
                        CreateParameterForValue(
                            command,
                            GetOriginalParameterName(i),
                            sourceColumn,
                            DataRowVersion.Original,
                            parameterCount,
                            value,
                            row, (isUpdate ? StatementType.Update : StatementType.Delete), true
                        )
                    );
                    parameterCount++;
                    builder.Append(RightParenthesis);

                    builder.Append(RightParenthesis);
                }

                if (IncrementWhereCount(row))
                {
                    whereCount++;
                }
            }

            builder.Append(RightParenthesis);

            if (0 == whereCount)
            {
                if (isUpdate)
                {
                    if (ConflictOption.CompareRowVersion == ConflictOption)
                    {
                        throw ADP.DynamicSQLNoKeyInfoRowVersionUpdate();
                    }
                    throw ADP.DynamicSQLNoKeyInfoUpdate();
                }
                else
                {
                    if (ConflictOption.CompareRowVersion == ConflictOption)
                    {
                        throw ADP.DynamicSQLNoKeyInfoRowVersionDelete();
                    }
                    throw ADP.DynamicSQLNoKeyInfoDelete();
                }
            }
            return parameterCount;
        }