Is there a difference between Select * and Select [list each col] [duplicate]

Answer 1

For LinqToSql, if you plan to modify those records later, you should pull the whole record into memory.

Answer 2

selecting each column is better than just * because in case you add or delete a new row you HAVE to look at the code and take a look what you were doing with the retrieved data.
Also, it helps you understand your code better and allows you to use aliases as column names (in case you're performing a join of tables with a column sharing the name)

Answer 3

Generally, it's better to be explicit, so Select col1, col2 from Table is better. The reason being that at some point, an extra column may be added to that table, and would cause unneeded data to be brought back from the query.

This isn't a hard and fast rule though.

Answer 4

SELECT * is a bad practice in most places.

• What if someone adds a 2gb BLOB column to that table?
• What is someone adds really any column to that table?

It's a bug waiting to happen.

Answer 5

A couple things:

• A good number of people have posted here recommending against using *, and given several good reasons for those answers. Out of 10 other responses so far only one doesn't recommend listing columns.
• People often make exceptions to that rule when posting to help sites like StackOverflow, because they often don't know what columns are in your table or are important to your query. For that reason, you'll see a lot of code here and elsewhere on the web that uses the * syntax, even though the poster would tend to avoid it in his own code.

Answer 6

A quick look at the query execution plan shows that the querys are the same.

The general rule of thumb is that you will want to limit your queries to only the fields that you need returned.