Insert into SQL with "-" char

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1.00/5 (3 votes)

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Insert into sql with "-" char

I have result    exp  1.00
 
How to insert into to have value -1.00?
 
Thank you

What I have tried:

using (SqlCommand cmd = new SqlCommand("INSERT INTO dbo.mp_list (iznos_sa_pdv, kupac) VALUES(@iznos_sa_pdv)", con))  
{  
cmd.Parameters.Add("@iznos_sa_pdv", SqlDbType.VarChar, 255).Value = ukupnolabel.Text;  
}

Posted 12-Dec-19 1:04am

Goran Bibic

Updated 12-Dec-19 1:30am

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Afzaal Ahmad Zeeshan 12-Dec-19 7:07am

~~Never mind~~

And what gets stored in the database after this code executes?

Goran Bibic 12-Dec-19 7:16am

This is part of code, in database is value 1.00
I need to save in database value -1.00

Need Help like this or...

cmd.Parameters.Add("@iznos_sa_pdv", SqlDbType.VarChar, 255).Value = '-'ukupnolabel.Text;

Dave Kreskowiak 12-Dec-19 8:41am

Why are you storing numbers as text in the database?

2 solutions

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phil.o · Answer 1 · 2019-12-12T01:29:00

A "brute-force" solution could be as simple as:

C#

cmd.Parameters.Add("@iznos_sa_pdv", SqlDbType.VarChar, 255).Value = $"-{ukupnolabel.Text}";

But be careful: if there is already a negative value in the textbox, you will end up with a value which is not a proper number.

It may be better to parse the string to a double, negate it, and provide the result back to the query:

C#

double value;
if (double.TryParse(ukupnolabel.Text, out value))
{
   value = -value;
   cmd.Parameters.Add("@iznos_sa_pdv", SqlDbType.VarChar, 255).Value = value.ToString();
}
else
{
   // Invalid value provided.
}

But there is an issue with your query: you specifiy two columns for INSERT statement but only provide a value for one of them.

Moreover, you should use proper data types in your database: if iznos_sa_pdv column is meant to hold real numbers, then it should not have a varchar type in the first place. It would then allow you to write

C#

double value;
if (double.TryParse(ukupnolabel.Text, out value))
{
   value = -value;
   cmd.Parameters.Add("@iznos_sa_pdv", SqlDbType.Float).Value = value;
}
else
{
   // Invalid value provided.
}

OriginalGriff · Answer 2 · 2019-12-12T01:31:00

Solution 2

If you want to change a value in an existing row, you don't INSERT - that always adds a new row.
Instead, you use UPDATE:

SQL

UPDATE MyTable SET MyColumn = @MyParameter WHERE MyIDColumn=@IDOFTheRowToChange

Posted 12-Dec-19 1:31am

OriginalGriff

v2