c# reading integer fields from database, returning empty string when reading integer type field

Question

what is wrong with this code?

field="id";
table="MInvMonth";
condition="machine_id=37";
 public static String getConditionedField(String field, String table, String condition)
    try
    {
        if (cmd == null) getConnection();
        cmd.CommandText = "Select " + field + " from " + table + " where " + condition;
        SQLiteDataReader reader = cmd.ExecuteReader();
        if (reader.HasRows==true)
        {
            reader.Read();
            string s = reader[0].ToString(); // return first element
            reader.Close();
            return s;
        }
        reader.Close();
        return null;
    }
    catch (Exception e)
    {
        MessageBox.Show("Caught exception: " + e.Message+"|"+cmd.CommandText);
        return null;
    }

I checked the sql statement, it turns the right value. why can't I read it? the returnvalue is "".

Have you tried setting a breakpoint on your string s = ... line? Try to add reader[0] to watch. What does it show? reader[1]? reader[2]? — Fyodor Soikin
– Fyodor Soikin, Commented May 16, 2010 at 13:35
JUst a word of advice, the way your setting up that sql command opens up oportunities for SQL Injection, u should look at using parametrized queries:csharp-station.com/Tutorials/AdoDotNet/Lesson06.aspx — Luis
– Luis, Commented May 16, 2010 at 14:10

Petar Minchev · Accepted Answer · 2010-05-16 13:32:48Z

1

Are you sure the zero index contains the value you need? Maybe it is another column.

answered May 16, 2010 at 13:32

Petar Minchev

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Comments

npinti · Accepted Answer · 2010-05-16 13:36:36Z

0

Sometimes the first element is 1 not 0, did you try replacing that?

answered May 16, 2010 at 13:36

npinti

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Comments

arnoldino · Accepted Answer · 2010-05-16 13:39:57Z

0

the first time I misstyped the sql staement. now it is good, it must return just the id field. The thing is, that this is a function and with other type of queries, when the returned field type is string, it is working fine.

I tried to debug, and the reader[0].value is empty.

answered May 16, 2010 at 13:39

arnoldino

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