Why is using '*' to build a view bad?

Question

Why is using \'*\' to build a view bad ?

Suppose that you have a complex join and all fields may be used somewhere.

Then you just have to chose fields needed

Answer 1

Although many of the comments here are very good and reference one common problem of using wildcards in queries, such as causing errors or different results if the underlying tables change, another issue that hasn't been covered is optimization. A query that pulls every column of a table tends to not be quite as efficient as a query that pulls only those columns you actually need. Granted, there are those times when you need every column and it's a major PIA having to reference them all, especially in a large table, but if you only need a subset, why bog down your query with more columns than you need.