Addition operating at a SQL query?

yokzu

Hello,
I just wanna do a simple operation. My sql query is below;

UPDATE IP_KONTROL SET up_down= '" + rdr["up_down"] + 1 + "' WHERE spe = '" + specif + "' ", conn

I just want to increase rdr's value 1, and Update it. I mean I want to increase rdr["up_down"]'s value. But it isnt adding +1. For example if rdr["up_dow"]'s value is 2, and then it is updating "21".. It should be "3", not "21". How can i do that?

2 Replies

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Suthish Nair15y ago
First of all this is not a good way to code your logic. This leads to SQL injection.

For more, refer article.
Subhendu De15y ago
There is a basic difference of + operator for string and int datatype.

int i = 2;
int j = 1;

(i+j) would give you (2+1) = 3. The mathematical sum happens here.

string i = "2";
string j = "1";

(i+j) would give you ("2" + "1") = "21". The concatenation happens here.

So do in this way

UPDATE IP_KONTROL SET up_down= '" + Convert.ToString( (Convert.ToInt32(rdr["up_down"]) + 1)) + "' WHERE spe = '" + specif + "' ", conn

Convert the string to int and then do the sum. Again convert it to string.

Thanks.....