Comments by giadich (Top 2 by date)

Select * isn't okay if you only want the whole table schema.

Back in the days when I was still new at [the company] and doing data analyst (with a little background in programming) work, one of the application keeps getting slower and slower by the week. Every time we loaded some data into SQL, it would take longer to run the app - from 1 minute to 5 minutes then 10 minutes... I was so frustrated and started to dig into the code and found the culprit - "Select *".

It turned out, one of our programmers wanted to get the schema of the table and used Select * to retrieve it. That is okay if the table is small but if your table is growing constantly then this will be a huge problem.

After discovering the problem, I changed the code to Select Top 0 * and the problem was gone and the app ran faster than ever. So if you really want to get the schema of the table and do not know it before hand and need to used Select *, make sure you limit the number of rows returned.