if-else条件用于更新SQL Server 2005中存储过程中的表

Question

I want to update some data in a specified case, else these columns are not to be updated.

What can I write code in a stored procedure for this?

Answer 1

You can use a case to control whether you assign a new value or keep the old value.

update <sometable>
set field = case when <condition> then <newvalue> else field end
where <condition>

Example:

update questions
set reply = case when @input is not null then @input else reply end
where answer = 42

Answer 2

Use Case statement in Update clause

like

SQL Statement #6

UPDATE titles
       SET price =
                 CASE
                   WHEN (price < 5.0 AND ytd_sales > 999.99)
                                   THEN price * 1.25
                   WHEN (price < 5.0 AND ytd_sales < 1000.00)
                                   THEN price * 1.15
                   WHEN (price > 4.99 AND ytd_sales > 999.99)
                                   THEN price * 1.2
                   ELSE price
                 END

Taken from SQL SERVER UPDATE

Also you can go with if..else statement

If you would have been in SQL SERVER 2008, you could have avail the flavor of MERGE statement

Answer 3

Just an example:

IF @a <= 0 
BEGIN
    UPDATE table SET counter = @a, name = 'Minati'
END
ELSE
BEGIN
    UPDATE table SET name = 'Minati'
END

Answer 4

May be you can build the condition in the update command and easily run more than one update with the diferent conditions. It may not be the most elegant way but it is prety eficient. It depends of your needs.

UPDATE table SET field=value WHERE <<condition>>
UPDATE table SET field=value2 WHERE <<condition2>>