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Code help for understanding countHashMap

Posted on 2006-10-26
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Last Modified: 2010-03-31
Hi
I have 20 categories of product, Each category contains more than 100 products. I want to create a java class that will query the database and get  the total number of products under each category, Like this:

Spiderman Category = Total products under this category 65

I can see that "countHashMap" will do the trick, but I am not sure how to use it. I know the question can be confusing so pls ask me if you need more information. Thank you in advance to anyone who jumps in:)
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Question by:atwork2003
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LVL 86

Expert Comment

by:CEHJ
ID: 17814054
select count(*) from product_table where category = 65

?
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LVL 86

Expert Comment

by:CEHJ
ID: 17814071
Then you can do

map.put(65, resultSet.getInt(1));

(assuming >= Java 1.5)
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LVL 14

Assisted Solution

by:hoomanv
hoomanv earned 800 total points
ID: 17814209
> get the total number of products under each category

Assume you have two tables: category_table and product_table
category_table columns: id (primary key) | name | ...
product_table columns: category_id (foreign key) | ...

SELECT category_name,COUNT(category_id)
FROM category_table,product_table
where id = category_id
GROUP BY category_name
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Author Comment

by:atwork2003
ID: 17814263
Thank you for quick and great response. I am trying these out, will update soon to get more insight:)
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Accepted Solution

by:
owenli27 earned 1200 total points
ID: 17814270
create a function to return a Map object:

Class.forName("oracle.jdbc.driver.OracleDriver");
Connection conn = DriverManager.getConnection(
      "jdbc:oracle:thin:@xyz.abcdef.com:1521:yourSID","username","password");

String sql = "select categoryName, count(*) as Total from yourTableName group by categoryName order by categoryName";
PreparedStatement stmt = conn.prepareStatement(sql);
ResultSet rs = stmt.executeQuery();

Map mp = new HashMap();
while (rs.next()) {
      mp.put(rs.getString("categoryName"), rs.getString("Total"));
}
rs.close();
stmt.close();
conn.close();
retunr mp;
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Author Comment

by:atwork2003
ID: 17906518
Thanks a lot guys:) Sorry forgot to close the question, apologize for the inconvenience.

Thank you
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