Question

I have requirement to remove the duplicate values from result set based on some unique identifier.

I need to remove the duplicates from the result set.

  while(resultSet.next())
  {     
   int seqNo = resultSet.getInt("SEQUENCE_NO");

   String tableName = resultSet.getString("TABLE_NAME");

   String columnName = resultSet.getString("COLUMN_NAME");

  String filter = resultSet.getString("FILTER");

 }

from the above iteration, i m getting 2 rows from result set. There is same seq no,same table name, different columnname, same filter.

1 PRODUCTFEES CHARGETYPE PRODUCTID

1 PRODUCTFEES PRODUCTCODE PRODUCTID

My requirement is to remove the duplicate table name, duplicate seq no, duplicate filter.

I want to get output something below,

1 PRODUCTFEES CHARGETYPE PRODUCTCODE PRODUCTID

Answer 1

By the example you provide, it seems like you want to output all distinct values for each column indidivually (there are 4 columns in the table, but you output 5 values).

Being the question tagged java, an approach you could take would be using an implementation of Set for each of the columns, so that duplicates won’t get through. Then output all the elements of each Set.

LinkedHashSet[] sets = new LinkedHashSet[]{
    new LinkedHashSet(), 
    new LinkedHashSet(),
    new LinkedHashSet(),
    new LinkedHashSet() };

while(resultSet.next()) {     
    sets[0].add(resultSet.getInt("SEQUENCE_NO"));
    sets[1].add(resultSet.getString("TABLE_NAME")););
    sets[2].add(resultSet.getString("COLUMN_NAME"));
    sets[3].add(resultSet.getString("FILTER"));
}

StringBuilder buf = new StringBuilder();
for (LinkedHashSet set : sets) {
    // append to buf all elements of each set
}

But it might be simpler to address this from the very same SQL query and just make SELECT DISTINCT columnX for each of the columns and output the result without further manipulation. Or use an aggregation function that will concatenate all distinct values. The implementation will be highly dependent on the DBMS you’re using (GROUP_CONCAT for MySQL, LISTAGG for Oracle, …). This would be a similar question for Oracle: How to use Oracle’s LISTAGG function with a unique filter?