Question

Is it ok to store data of different data types as a single universal data type, say ‘image’ in SQL? I will also store the data type value in another column and use this value inside my code to convert the data back into its proper type.
The advantage I get by doing this – I can avoid joining n number of tables.
Can some one point me to the down sides of storing data in this way?

Answer 1

This is a pretty bad idea for several reasons:

• Query performance will be bad because the optimizer can’t utilize indexes, foreign keys etc. because they don’t exist.
• You don’t get referential integrity and thus can make no assumption about your data.
• You introduce a new additional point of failure, because what if the data doesn’t correspond to the specified data type?
• The person having to maintain the code after you will hate you.