Wednesday, June 28, 2017

Count Unique Values in Oracle and Microsoft Access

I have found that it is convenient to use Microsoft Access to create an external link to a Spreadsheet and run SQL queries against it.

In a recent project, I want to count the name of unique name in table t_test. If it is an Oracle table, it can be done using "count(distinct name)" as the following:

select count(distinct name) from t_test;
However, t_test is an linked external spreadsheet within an Access database. Access does not support "count(distinct "). So I first find the unique name and then count the number of records using the following query:
select count(*) from
SELECT  distinct name
FROM t_test