1) the first “catch-phrase” to memorize is the most common
– – – > prepare/execute/fetch
All 3 methods are specified in DBI but implemented (vendor-specific) in DBD modules ie DBD drivers.
2) For non-select, prepare/execute will do.
3) The simplest: do() alone can replace prepare/execute.
5) stored procedure with 3 result sets ie 3 selects: prepare/execute /fetch/more_results/fetch/more_results/fetch
Beware that most of these methods belong to $statement_handle like
– – – – > $statement_handle -> method1
whereas a few belong to $db_handle.
 excluding select-into. I think a select-into always returns one(???) row and saves it into variables and does not produce a result set.