public String buildDropColumnStatement(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.getOldColumn(), "Old column is null");
            Column column = expression.getOldColumn();
            Preconditions.checkState(column.getName() != null && !column.getName().trim().isEmpty(),
                    "The column name is blank");
            sb.append("DROP COLUMN `").append(column.getName()).append("`");
            if (iterator.hasNext()) {
                sb.append(",");
            }
        }
        return sb.toString();
    }
Build the statement of DropColumn

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