SQL Server DBLlink to oracle returns numbers as string

Question

I have an Oracle database containing my data and an SQL Server database getting the data from Oracle through DBLink. Problem is - all numbers from the Oracle tables are accepted at the SQL Server as nvarchar. As a result, when i try to filter the query in the SQL Server with some_number_field = 0 i get: "Conversion failed when converting the nvarchar value '3.141' to data type int." This also happens if i try to select "some_number_field * 1" or similar expressions. Any idea ?

Answer 1

Today I ran into the same kind of problem. It seems that Oracle field with datatype NUMBER are shown as nvarchar where querying through a linked server. However, NUMBER(x,y) not.

Eg colB is the NUMBER field from an Oracle View (or table) Try this:

SELECT colA, CAST(colB AS DECIMAL(23,2)) colB
FROM OPENQUERY(LINKED_SERVER_NAME, 'select * from myView')

Note: the DECIMAL(xx,y) values depends of course on your data. Also, remember, if your NUMBER column is a repetitive fraction (eg. 33.33333333 etc), you need to place a round() on the oracle side otherwise the CAST will throw an error.