Convert a Result Set from SQL Array to Array of Strings

Matt picture Matt · Feb 18, 2013 · Viewed 82.8k times · Source

I am querying the information_schema.columns table in my PostgreSQL database. Using a table name, the result set finds all the column names, type, and whether it is nullable (except for the primary key, 'id'). This is the query being used:

SELECT column_name, is_nullable,data_type FROM information_schema.columns
WHERE lower(table_name) = lower('TABLE1') AND column_name != 'id'
ORDER BY ordinal_position;

I have a string array for each of these results and I am trying to use the ResultSet method getArray(String columnLabel) to avoid looping through the results. I want to store the returned Arrays in the string arrays, but get a type mismatch error

Type mismatch: cannot convert from Array to String[]

Is there a way to convert or typecast the SQL Array object to a String[]?

Relevant Code:

String[] columnName, type, nullable;

//Get Field Names, Type, & Nullability 
String query = "SELECT column_name, is_nullable,data_type FROM information_schema.columns "
        + "WHERE lower(table_name) = lower('"+tableName+"') AND column_name != 'id' "
        + "ORDER BY ordinal_position";

try{
    ResultSet rs = Query.executeQueryWithRS(c, query);
    columnName = rs.getArray(rs.getArray("column_name"));
    type = rs.getArray("data_type");
    nullable = rs.getArray("is_nullable");
}catch (Exception e) {
    e.printStackTrace();
}

Answer

BobTheBuilder picture BobTheBuilder · Feb 18, 2013

Use:

Array a = rs.getArray("is_nullable");
String[] nullable = (String[])a.getArray();

As explained here

Array is SQL type, getArray() returns an object to cast to java array.