Count no. Of visit from db by SQL query?

Question

4.33/5 (2 votes)

See more:

i want to total no. of visited patient.
i make following code in c# as:

OleDbCommand vst = new OleDbCommand("select count(*) from old_patient where Contact_no=@Contact_no GROUP BY Contact_no", cn);
                        vst.Parameters.Add(new OleDbParameter("@Contact_no", txtsno.Text));

                        //  store value in rec variable.
                        int rec = (int)vst.ExecuteNonQuery();
                        lbldtr.Text = rec.ToString();

txtsno is textbox;
lbldtr is label where i want to show or print answer.

in txtsno textbox have contact no. so , i want to get particular contact no. visit.

thank u in advance

What I have tried:

OleDbCommand vst = new OleDbCommand("select count(*) from old_patient where Contact_no=@Contact_no GROUP BY Contact_no", cn);
                        vst.Parameters.Add(new OleDbParameter("@Contact_no", txtsno.Text));

                        //  store value in rec variable.
                        int rec = (int)vst.ExecuteNonQuery();
                        lbldtr.Text = rec.ToString();

Posted 18-Sep-16 23:25pm

Member 11572517

Updated 18-Sep-16 23:36pm

Suvendu Shekhar Giri

v2

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Suvendu Shekhar Giri · Accepted Answer · 2016-09-18T23:34:00

Solution 1

You probably have forgotten to write your problem in the question.
Looking at your code, it has following mistakes
1. Query seems to be incorrect

SQL

select count(*) from old_patient where Contact_no=@Contact_no GROUP BY Contact_no

It should be-

SQL

select count(*) from old_patient where Contact_no=@Contact_no

2. You should use ExecuteScalar instead of ExecuteNonQuery

C#

int rec = (int)vst.ExecuteNonQuery();

it should be-

C#

int rec = (int)vst.ExecuteScalar();

Here is a detailed article for detailed reading-
Difference between ExecuteReader ExecuteScalar and ExecuteNonQuery[^]

Hope, it helps :)
If you find further difficulties, please let me know.

Posted 18-Sep-16 23:34pm

Suvendu Shekhar Giri

Comments

Karthik_Mahalingam 19-Sep-16 5:39am

5! much better and clean.

Suvendu Shekhar Giri 19-Sep-16 5:42am

Thanks @Karthik :)

Member 11572517 19-Sep-16 5:50am

both of u expert supeerb, it's clear. thank u so muchhhhhhhhhhhhhhhhhhhhhh.

Suvendu Shekhar Giri 19-Sep-16 5:57am

Thanks for those kind words :)
Glad that it helped resolve your issue.

Maciej Los 19-Sep-16 6:58am

5ed!

Suvendu Shekhar Giri 19-Sep-16 7:28am

Thanks :)

Karthik_Mahalingam · Accepted Answer · 2016-09-18T23:36:00

Solution 2

use ExecuteScalar [^]
ExecuteNonQuery will return the number of rows affected, not the actual value which you want to return.

C#

int rec = (int)vst.ExecuteScalar();

Posted 18-Sep-16 23:36pm

Karthik_Mahalingam

Comments

Suvendu Shekhar Giri 19-Sep-16 5:42am

Simple and straight :)
5Ed!

Karthik_Mahalingam 19-Sep-16 5:44am

Thank you SSG :)

Member 11572517 19-Sep-16 5:50am

thank both of u sir.........

Karthik_Mahalingam 19-Sep-16 5:51am

welcome :)

Maciej Los 19-Sep-16 6:58am

5ed!

Karthik_Mahalingam 19-Sep-16 6:59am

Thank you Maciej