Addition operating at a SQL query?

Question

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?

Suthish Nair · Answer

First of all this is not a good way to code your logic. This leads to SQL injection. For more refer article .

Subhendu De · Answer

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.....