Inconsistent Datatypes: Expected NUMBER Got DATE with Oracle’s Analytic Functions

In this article, we will delve into the intricacies of Oracle Database 18c Enterprise Edition Release 18.0.0.0.0 - Production Version 18.3.0.0.0 and explore why it throws an error when using analytic functions to calculate dates.

Understanding the Issue

The provided SQL code creates a view that utilizes analytic functions to calculate various values. However, when the total_days field is calculated using the expression ( trunc(sysdate) - a.first_transaction_date ) / 2, Oracle Database throws an ORA-00932 error: “inconsistent datatypes: expected NUMBER got DATE”.

To better understand this issue, let’s break down the components of the problem.

Analytic Functions in Oracle

Analytic functions are used to perform calculations on a set of data that is partitioned by one or more columns. These functions can be useful for tasks such as calculating aggregates, ranking records, and determining the first occurrence of a value within a partition.

In this example, we use an analytic function min to calculate the first record in each partition (i.e., the earliest transaction date). The (partition by null order by null) clause is used to specify that there should be no partitions; instead, all records will be treated as individual rows.

The Calculation of Total Days

The calculation of total_days involves subtracting the first_transaction_date from the current date (sysdate). This operation yields a difference in days between these two dates.

However, when we divide this difference by 2 using the expression ( trunc(sysdate) - a.first_transaction_date ) / 2, Oracle Database expects the result to be of type NUMBER. Instead, it returns an error because trunc(sysdate) and a.first_transaction_date are both of type DATE.

The Solution

To resolve this issue, we need to cast one of the values to NUMBER before performing the division. This is achieved by wrapping the expression with the to_char function:

create or replace view test as
with
   wData as --Create a record set
      (
      select trunc(sysdate - 2) as transaction_date, 1 as transaction_amount from dual union all
      select trunc(sysdate - 1) as transaction_date, 2 as transaction_amount from dual union all
      select trunc(sysdate - 0) as transaction_date, 3 as transaction_amount from dual
      ),
   wTransactions as --Use an analytic function to calculate first record and assign to each record
      (
      select min(a.transaction_date) over (partition by null order by null) as first_transaction_date,
             a.transaction_date,
             a.transaction_amount
      from   wData a
      ),
   wTotals as --Sum the amounts
      (
      select a.*,
           to_char( trunc(sysdate) - a.first_transaction_date )                  / 2 as total_days, -- Fixed Calculation
           --
             sum(a.transaction_amount) over(partition by null order by null) as total_transaction_amount 
           --0 / 1                                                           as total_transaction_amount 
      from   wTransactions a
      )
select a.first_transaction_date,
       a.total_days,
       a.transaction_date,
       a.transaction_amount,
       a.total_transaction_amount
from wTotals a;

By casting the difference to NUMBER, we ensure that the division is performed correctly and yields an expected result of type NUMBER.

Conclusion

In conclusion, when using analytic functions in Oracle Database 18c Enterprise Edition Release 18.0.0.0.0 - Production Version 18.3.0.0.0, it’s essential to be aware of potential issues related to inconsistent datatypes. By understanding the behavior of these functions and taking steps to cast values appropriately, we can write more robust and error-free SQL code.

In this article, we’ve explored how to resolve an ORA-00932 error caused by a divide-by-zero operation when using analytic functions. We’ve also demonstrated the importance of careful consideration when working with date and number data types in Oracle Database.

I hope you found this article informative and helpful. If you have any questions or need further clarification, please don’t hesitate to ask.

Last modified on 2024-08-03