更新查询，该查询将使用同一表的另一条记录中的值设置记录中的特定列

Question

look at this query;

update user_data set old_status= 'SNNNNS',
                     user_group='15',
                     default_rate='DEFAULT',
                     entity_num='1001'
where user_name='Dasu';

I know I could write the query like that and get result, but I dont want to be writing the values. These values are from another record with user_name 'sys' in the same table. I want a query that will update these particular columns in 'Dasu' with values from 'sys'.

Any idea?

Answer 1

In Oracle, you can use merge with a self-join. Alternatively, you can write correlated subqueries in the update :

update user_data
    set (old_status, user_group, default_rate, entity_num) = (select old_status, user_group, default_rate, entity_num from user_data where user_name = 'sys')
where user_name='Dasu';

Answer 2

You can nest a select in your update statement. For Example:

UPDATE Dasu
SET old_status = (SELECT old_status FROM sys WHERE Id = 1)