Why is explicit error variable declaration required with database handle?

When creating a database handle, where the the variable 'db' is declared outside of main, why does this produce a panic:

db, err := sql.Open("mysql", "user:pass@unix(/path/mysqld.sock)/dbname")

but this doesn't:

var err error
db, err = sql.Open("mysql", "user:pass@unix(/path/mysqld.sock)/dbname")

the panic is a nil pointer dereference when the first query is run.

I'm fairly sure this exact piece of code is not what's causing your problem, you may need to provide more context.

Sounds like a scope error. Probably DB is both a package variable and a function variable but without context that’s just a guess. 

Or something even dumber.  I cut it down to just enough code to make a database handle and run a query and now I can't reproduce it, go figure.

Thanks for the help though, both of you.  

I'm sure you had db var declared global, so with := you created a local db var, and didn't touch the global, which remained nil.