The parameter placeholder token forms a dialect's drivers accept: 'at-name' (@name), 'question' (?), 'dollar-number' ($1), 'colon-name' (:name), 'colon-number' (:1).
'at-name'
@name
'question'
?
'dollar-number'
$1
'colon-name'
:name
'colon-number'
:1
The parameter placeholder token forms a dialect's drivers accept:
'at-name'(@name),'question'(?),'dollar-number'($1),'colon-name'(:name),'colon-number'(:1).