how to add a variable value to a database value?

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i m making an application on windows form using c# and sql is the database.
i wanna do this
Quantity = Quantity + q_var
where
Quantity is a database column and q_var is a variable

i know how to use sql UPDATE command. but tell me how can i perform that airthmetic operation?

Posted 19-Jun-11 5:38am

Sweety Khan

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thatraja 20-Jun-11 1:58am

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5 solutions

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**theanil** · Answer 1 · 2011-06-19T07:22:00

Solution 1

just use dataset and sqladdapter

DataRow dRow = ds1.Tables["table name"].Rows[row number];

variable a = dRow.ItemArray.GetValue(column number).ToString();

Quantity = Quantity + q_var

a = a+q_var...

Posted 19-Jun-11 7:22am

theanil

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[no name] 21-Jun-11 9:16am

Sweety Khan might need how to perform that arithmetic operation in UPDATE command

Sudhir Kumar Srivastava lko · Answer 2 · 2011-06-21T01:21:00

Solution 3

Look at this example : suppose table name Emp contains one column that is EmpId of int type.

in C# code :
declare variable of column type exist in DB

int I=20;

create connection from C# to SQl server and pass this query from the C#:

select EmpId + I from Emp,

u will find the Result.

Posted 21-Jun-11 1:21am

Sudhir Kumar Srivastava lko

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[no name] 21-Jun-11 9:17am

Sweety Khan might need how to perform that arithmetic operation in UPDATE command.

Sweety Khan 21-Jun-11 11:56am

sangunni is right but bc of lack of time i dont studied n do this through what i know
i first bring the value from database.
then add it to the variable
n in then send it back to the database means i use one select command n one update

2irfanshaikh · Answer 3 · 2011-06-21T01:26:00

Solution 4

why don't you try this in a store procedure???

Posted 21-Jun-11 1:26am

2irfanshaikh

Comments

[no name] 21-Jun-11 9:17am

That is a good thought, since Sweety Khan need something to perform arithmetic operation in UPDATE

[no name] 22-Jun-11 0:56am

use CTE (common table expression Query )

Liju Sankar · Answer 4 · 2011-06-21T03:14:00

Solution 5

SQL

DECLARE @tmpTable as Table (Quantity INT)
INSERT INTO @tmpTable (Quantity) VALUES (100)
SELECT * FROM @tmpTable
UPDATE @tmpTable SET Quantity =Quantity +100
SELECT * FROM @tmpTable

Result Before update:100
Result After update:200

Posted 21-Jun-11 3:14am

Liju Sankar

Updated 21-Jun-11 3:15am

v3

ElectronicShocker · Answer 5 · 2011-06-20T17:57:00

Solution 2

If you Google it, you might find some ways to do it.

Posted 20-Jun-11 17:57pm

ElectronicShocker