Call SQL Query in lable

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1.00/5 (1 vote)

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Please help me.

I wrote this code but it doesn't work.

What is my mistake and what is the correct code ?

C#

protected void Page_Load(object sender, EventArgs e) 
{ 
  SqlCommand cmd = new SqlCommand(); 
  cmd.Connection = new SqlConnection(Class1.CnnStr);

  cmd.CommandText = "SELECT MAX(Code) FROM Customer"; 
  cmd.Connection.Open();   
  cmd.Parameters.AddWithValue(Code_lbl.Text,"@MAX(Code)"+1);   
  cmd.ExecuteNonQuery(); 
 }

Posted 29-Oct-11 3:39am

kitykity

Updated 29-Oct-11 3:44am

Nueman

v3

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Nueman 29-Oct-11 9:45am

Readability. Put code in block

kitykity 29-Oct-11 9:56am

How?please write it for me I don't know how to do this

2 solutions

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OriginalGriff · Answer 1 · 2011-10-29T04:09:00

That doesn't work because it is thrown together from a variety of sources, without thinking too hard what you are doing.

SQL

SELECT MAX(Code) from Customer

Does not have any parameters so trying to add them is not going to help.
Even if it did, what is the value of a string plus the number one? Answer: a string with a "1" on the end. So your code

"@MAX(Code)"+1

is actually the same as

"@MAX(Code)1"

Your Label.Text almost certainly doesn't contain the name of a parameter in your SQL statement even if you actually had any.

C#

cmd.ExecuteNonQuery();

Is a waste of time with a SELECT sql command because a SELECT command does not affect any rows in the table, it just returns them based on the selection criteria. Except that even if it did return any rows, you then throw then away, because ExecuteNonQuery returns the number of rows affected.

Without a better description of what you are actually trying to do, I can't tell you what is wrong with it, because everything is wrong - it doesn't do anything useful at all, so I can't tell what you were trying to do!

Nueman · Answer 2 · 2011-10-29T05:30:00

Solution 2

What Griff said.

Get rid of the cmd.Parameters. You have no parameters.

Also, your SQL query returns a discrete (single) value from the database. You want to use ExecuteScalar.

I am not going to code it for you, there are numerous references online. Google: "ExecuteScalar".

Posted 29-Oct-11 5:30am