Question

Based on this question here Selecting NOT NULL columns from a table One of the posters said

you shouldn’t use SELECT * in production.

My Question: Is it true that we shouldn’t use Select * in a mysql query on a production server? If yes, why shouldn’t we use select all?

Answer 1

Most people do advise against using SELECT * in production, because it tends to break things. There are a few exceptions though.

• SELECT * fetches all columns – while most of the times you don’t
  need them all. This causes the SQL-server to send more columns than
  needed, which is a waste and makes the system slower.
• With SELECT *, when you later add a column, the old query will also
  select this new column, while typically it will not need it. Naming
  the columns explicitly prevents this.
• Most people that write SELECT * queries also tend to grab the rows
  and use column order to get the columns – which WILL break your code
  once columns are injected between existing columns.
• Explicitly naming the columns also guarantees they are always in the same order, while SELECT * might behave differently when the table column order is modified.

But there are exceptions, for example statements like these:

INSERT INTO table_history
SELECT * FROM table 

A query like that takes rows from table, and inserts them into table_history. If you want this query to keep working when new rows are added to table AND to table_history, SELECT * is the way to go.