Error 16 Cannot implicitly convert type 'object' to 'string'. An explicit conversion exists (are you missing a cast?)

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C#

public string generateFNo()
            {
                String str = "SELECT Max(fdk_No) From tblFeedback";
                string fNo = null;
                SqlCommand con = new SqlCommand(str, cn);
                cn.Open();

                if (con.ExecuteScalar().Equals(DBNull.Value))
                {
                    fNo = "F01";
                }
                else
                {
                     fNo = con.ExecuteScalar();

         //Display the new fdkno (by get the last fdkno  from db)+1
                    string[] splitCode = Strings.Split(fNo, "F", 2);
                  fNo = "F0" + ((Convert.ToInt32(splitCode[1])) + 1).ToString();
                }

                cn.Close();
            }
        }

Posted 16-Dec-14 2:18am

Member 11308948

Updated 16-Dec-14 2:23am

CPallini

v2

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2 solutions

Solution 2

you are assign object to a string. as the answer1 explains you can fix the issue but!
if you trying to get the next fdk_No based on this result you will end up with several issues.
if two users connect and try to get the max id, both of them will have the same next fdk_No. when they insert records you will have duplicates or if you have unique or primary key then on of the insert will fail.
you better separate the string part of the fdkno and the numeric part in separate columns. numeric part can be set auto incremented, then you don't need to worry about duplicates and also you don't need to read current maximum value before insert. database will handle all of these.
when you need to get the fdk_No you can join these two column values in the select statement and get it as one value. hope this helps.

Posted 16-Dec-14 2:43am

DamithSL

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CPallini · Accepted Answer · 2014-12-16T02:25:00

Solution 1

Change from

Quote:
fNo = con.ExecuteScalar();

to

fNo = (string) con.ExecuteScalar();

Posted 16-Dec-14 2:25am

CPallini