if pgerrs.Is(err, pgerrs.CheckViolation) {
    println("violates a CHECK")
}

if pgerrs.ViolatesForeignKeyConstraint(err, "users", "address_id") {
    println("cannot add user, invalid address_id")
}

if pgerrs.ViolatesUniqueConstraint(err, "users", "email") {
    println("user with the given email already exists")
}

if pgerrs.ViolatesConstraint(err, "connections_from_to_key") {
    println("there can be only one connection with the given `from` and `to`")
}