In a Mental Status Examination a psychiatrist will assess the patient, often to decide whether they should be admitted to hospital. Quoting the article linked above, “Orientation is assessed by asking the patient … what time it is (time, day, date)”. So the patient is asked what day of the week it is. What if […]
Here are some issues which may catch you out from time to time. In each case Sql Server and Oracle, or Oracle Sql and PL/Sql, or versions of Oracle, work differently.
This is a basic tip that will save time when a query isn’t returning the expected results (typically, it’s bringing back an empty set) and you need to find out which join or WHERE clause filter is causing the problem. It’s not impossible to do, of course, but it’s nice to have a method that […]
As you probably realise, this post deals with apportionment in finance data warehouses, not the U.S. Constitutional Apportionment Problem, interesting though that topic is.
An ETL batch should not fail because of minor source data errors. In data warehousing it is assumed that there will be data quality issues. These should be dealt with. If they are not handled properly the batch may break on flaws which have no importance in reporting terms. Oracle’s DML Error Logging feature has […]
In a data warehouse you may have to drop columns on very large tables (try to avoid it if you can), and the size of the table may cause complications. The most obvious is the time it may take to do a straightforward ALTER TABLE DROP COLUMN statement. You probably don’t want to wait for […]
I work in data warehousing in banking, where we handle large amounts of data and have to change complex sql statements to fix bugs etc.. Individual queries tend to get bigger and bigger. The danger is that they become so complex that fixing one bug can break other parts of the logic.