SQL Server Express and C# : Database Charting [ANSWERED]

SQL Server Express and C# : Database Charting

Asked By: mcoliver88
Originally Asked On: 2014-01-02 11:27:07
Asked Via: stackoverflow

I am trying to link my SQL Server Express database to a chart in a c# application. I am trying to extract the age of some employees to display them in a bar char. Here is my code

string constring = "Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\Michael\Downloads\Employee\Employee\Employee\EmployeeDetails.mdf;Integrated Security=True;User Instance=True;Initial Catalog=Employee";

SqlConnection conDatabase = new SqlConnection(constring);
SqlCommand cmdDatabase = new SqlCommand("Select * from Employee;", conDatabase);
SqlDataReader myReader;

try{
    conDatabase.Open();
    myReader=cmdDatabase.ExecuteReader();

    while(myReader.Read())
    {
        this.chart1.Series["Age"].Points.AddXY(myReader.GetString("FirstName"), myReader.GetInt32("Age"));
    }
}

When I compile my program, I get 4 error messages, which relate to this line:

(myReader.GetString("FirstName"), myReader.GetInt32("Age"))

The error messages are:

The best overloaded method match for ‘System.Data.Common.DbDataReader.GetString(int)’ has some invalid arguments
Argument 1: cannot convert from ‘string’ to ‘int’
The best overloaded method match for ‘System.Data.Common.DbDataReader.GetInt32(int)’ has some invalid arguments
Argument 1: cannot convert from ‘string’ to ‘int’

The SQL Server Express database uses VARCHAR for FirstName and INT for Age

what have i done wrong?

He received 4 answers
eventually accepting:

StuartLC’s answer to

SQL Server Express and C# : Database Charting

IDataReader‘s .Get* methods only take the index of the column to be accessed, not the column name.

So instead of

myReader.GetString("FirstName")

You’ll need something like

myReader["FirstName"].ToString()

and

Convert.ToInt32(myReader.GetInt32("Age")))

If you are doing this in a tight loop, then you can cache the name : index mappings.

The answer with the highest score with 2 points was:

Soner Gönül’s answer to

SQL Server Express and C# : Database Charting

Error 1 The best overloaded method match for
‘System.Data.Common.DbDataReader.GetString(int)’ has some invalid
arguments

DbDataReader.GetString method takes argument as an int, not string.

Gets the value of the specified column as an instance of String.

public abstract string GetString(
    int ordinal
)

Use this method with what is the zero-based column ordinal of your FirstName and Age columns.

Error 2 Argument 1: cannot convert from ‘string’ to ‘int’

There is no implicit conversation from string to int. You get this error actually because myReader.GetString("FirstName") method returns string but your AddXY() method probably except int as a first parameter.

If the selected answer did not help you out, the other answers might!

All Answers For: SQL Server Express and C# : Database Charting

StuartLC’s answer to

SQL Server Express and C# : Database Charting

IDataReader‘s .Get* methods only take the index of the column to be accessed, not the column name.

So instead of

myReader.GetString("FirstName")

You’ll need something like

myReader["FirstName"].ToString()

and

Convert.ToInt32(myReader.GetInt32("Age")))

If you are doing this in a tight loop, then you can cache the name : index mappings.

ayilmaz’s answer to

SQL Server Express and C# : Database Charting

you should use GetString(0) or GetString(1) or GetString(2)

Soner Gönül’s answer to

SQL Server Express and C# : Database Charting

Error 1 The best overloaded method match for
‘System.Data.Common.DbDataReader.GetString(int)’ has some invalid
arguments

DbDataReader.GetString method takes argument as an int, not string.

Gets the value of the specified column as an instance of String.

public abstract string GetString(
    int ordinal
)

Use this method with what is the zero-based column ordinal of your FirstName and Age columns.

Error 2 Argument 1: cannot convert from ‘string’ to ‘int’

There is no implicit conversation from string to int. You get this error actually because myReader.GetString("FirstName") method returns string but your AddXY() method probably except int as a first parameter.

user3093781’s answer to

SQL Server Express and C# : Database Charting

Please try this code.

try{
    conDatabase.Open();
    myReader=cmdDatabase.ExecuteReader();

    chart1.DataSource = myReader;

    chart1.Series["Age"].XValueMember = "FirstName";
    chart1.Series["Age"].YValueMembers = "Age";

    chart1.DataBind(); 
}

Of course, you should really check out the original question.

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