C# database application

Question

here's my code

con.Open();
SqlCommand cmd = new SqlCommand("SELECT [Date] FROM [dbo].[DS_PROJECT] ORDER BY Date ASC", con);
cmd.ExecuteNonQuery();
SqlCommand cm = new SqlCommand("SELECT [Time] FROM [dbo].[DS_PROJECT] ORDER BY Time ASC", con);
cm.ExecuteNonQuery();
con.Close();
DateTime currenttime = DateTime.Now;
DateTime userdate = Convert.ToDateTime(cmd);
DateTime usertime = Convert.ToDateTime(cm);

i want to convert the date and time values saved in my database but am unable to do it and this exception occurs

Unable to cast object of type 'System.Data.SqlClient.SqlCommand' to type 'System.IConvertible

Please Help me. Thank You

Hi Ali, ExecuteNonQuery should be used for SQL commands that modify data (e.g. Inserts, Updates, Deletes). If you want to read data you should use ExecuteReader instead. See msdn.microsoft.com/en-us/library/9kcbe65k(v=vs.110).aspx — Rui Jarimba
– Rui Jarimba, Commented Jul 22, 2018 at 8:06
You get data by using ExecuteReader method of a SqlCommand and take data from the data reader it returns. There is a simple example on this page. — Richard
– Richard, Commented Jul 22, 2018 at 8:06
Sorry... what??? First you execute a query as non-query. Then you try to convert the query object to a value it should return. Start here: dotnetperls.com/sqldatareader — ZorgoZ
– ZorgoZ, Commented Jul 22, 2018 at 8:06
Also, if you want to get one and only one value from a SQL query you should use ExecuteScalar method, see msdn.microsoft.com/en-us/library/… — Rui Jarimba
– Rui Jarimba, Commented Jul 22, 2018 at 8:08

jcabey · Accepted Answer · 2018-07-22 08:29:37Z

1

Using ExecuteNonQuery() is intended for UPDATE, INSERT and DELETE queries that shouldn't return a value or a record set.

You can use ExecuteReader() to retrive multiple data records.

If you want to query for just a single value, you should use:

cmd.ExecuteScalar();

Note : Check for null first as it can return a a null reference if the result set is empty.

edited Jul 22, 2018 at 8:29

answered Jul 22, 2018 at 8:20

jcabey

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user6842156 · Accepted Answer · 2018-07-22 08:11:08Z

0

cm.ExecuteNonQuery()

The method is guess is not correct as per

https://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.executenonquery(v=vs.110).aspx

ExecuteNonQuery() returns the number of rows affected. Also the method is generally used when executing insert update or delete query. To get the result from the select statement, use the following blog by MSDN.

answered Jul 22, 2018 at 8:11

user6842156

3 Comments

Rui Jarimba Over a year ago

This is not an answer to the question, it should be a comment instead.

Ali Asad Over a year ago

can you edit the code , i am trying but there i am unable to do it?

user6842156 Over a year ago

@RuiJarimba I recently joined Stackoverflow and do not have enough rewards to comment. Thanks for suggestion.

Manoj M K · Accepted Answer · 2018-07-22 08:18:31Z

0

Normally, ExecuteNonQuery is used for the insert as well as update statement. You can use DataSet or DataReader , if you will have get multiple values from the database. Here in your case if you are using the query for single value retrieval, then you can use the ExecuteScalar menthod. which will return single value from the database. May be the below link will helpful..

http://csharp.net-informations.com/data-providers/csharp-sqlcommand-executescalar.htm

answered Jul 22, 2018 at 8:18

Manoj M K

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