unique index with multiple NULLs

MySQL unique index with null values

Can a database table have multiple rows with a NULL value in a column if there is a unique index on it? That seems like a question that we should have known the answer to from a basic RDBMS course from our studies. But for some reasons, some developers will say NO and some will strongly defend the YES option. Which group are you in?


Database performance for Hibernate developers course

Database performance for Hibernate developers

Have you ever wondered why database operations in your application are slow? Is it because of the database or Hibernate or both? Is there anything that can be done to improve that? What are those mysterious database indexes? Does using Hibernate leave me no field for performance optimization?


MySQL collations - why are there so much problems with them?

Do you share my feeling that any problem with encoding in MySQL database wastes a lot of your time? A few different settings, multiple possible combinations, you tried many of them and it is still not working? Maybe one of them was correct but should I restart MySQL instance, the whole server, the data center? Aaaaargh.


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