SQL Server到Oracle查询转换

Question

i have a code in sql server like this

IF EXISTS (SELECT * FROM address WHERE new_add=new_add)
    UPDATE address set old_add=old_add);
ELSE
    UPDATE address set old_add=new_add);

Its working properly in SQL Server. But its not working in oracle. It shows

SP2-0734: unknown command beginning "IF EXISTS ..." - rest of line ignored. 

Plese help me to change this query from SQL to Oracle. Thanks

Answer 1

SELECT 1 FROM address WHERE new_add=new_add

if @@RowCount > 0
 UPDATE address set old_add=old_add

Answer 2

In both databases, you can write the query as:

update address
    set old_add = old_add
    where exists  (SELECT * FROM address WHERE new_add = new_add);

The if is not needed at all.

However, this query is non-sensical. It either sets a column to itself in all rows (if the condition in the where matches at least one row). Or, it updates no rows (if the condition in the where has no matching rows). In either case, nothing really happens.