public String buildAddColumnStatement(List<AlterColumn> alterColumns) {
        Preconditions.checkState(alterColumns != null
                && !alterColumns.isEmpty(), "Alter columns is empty");
        Iterator<AlterColumn> iterator = alterColumns.iterator();
        StringBuilder sb = new StringBuilder();
        while (iterator.hasNext()) {
            AlterColumn expression = iterator.next();
            Preconditions.checkNotNull(expression.getNewColumn(), "New column is null");
            Column column = expression.getNewColumn();
            Preconditions.checkState(column.getName() != null && !column.getName().trim().isEmpty(),
                    "The column name is blank");
            sb.append("ADD COLUMN `").append(column.getName()).append("` ")
                    .append(convert2DorisType(expression.getNewColumn().getJdbcType(),
                            column.isNullable(), column.getDefinition()));
            if (validDefaultValue(column.getDefaultValue())) {
                sb.append(" DEFAULT ").append(quote(column.getDefaultValue()));
            }
            if (column.getComment() != null) {
                sb.append(" COMMENT ").append(quote(column.getComment()));
            }
            if (column.getPosition() != null && column.getPosition().getPositionType() != null) {
                if (column.getPosition().getPositionType() == PositionType.FIRST) {
                    sb.append(" FIRST");
                } else if (column.getPosition().getPositionType() == PositionType.AFTER) {
                    Preconditions.checkState(column.getPosition().getColumnName() != null
                            && !column.getPosition().getColumnName().trim().isEmpty(),
                            "The column name of Position is empty");
                    sb.append(" AFTER `").append(column.getPosition().getColumnName()).append("`");
                }
            }
            if (iterator.hasNext()) {
                sb.append(", ");
            }
        }
        return sb.toString();
    }
Build the statement of AddColumn

@param alterColumns The list of AlterColumn
@return A statement of AddColumn
inlong-sort/sort-flink/sort-flink-v1.13/sort-connectors/doris/src/main/java/org/apache/inlong/sort/doris/schema/OperationHelper.java