[Solved]Insert and modify the database at once

stereomatching

@
void komicaDB::add_message_number(std::map<QString, int> const &data) const
{
QSqlQuery qry;
qry.prepare("INSERT INTO komica_data (address, number) VALUES (?, ?)");

std::for_each(std::begin(data), std::end(data), [&](std::pair<QString, int> const &value)
{
  qry.addBindValue(value.first);
  qry.addBindValue(value.second);
  qry.exec&#40;&#41;;
}&#41;;

}
@

@
void komicaDB::update_message_number(std::map<QString, int> const &data) const
{
QSqlQuery qry;

qry.prepare("UPDATE komica_data SET number = ? WHERE address = ?");
std::for_each(std::begin(data), std::end(data), [&](std::pair<QString, int> const &value)
{
  qry.addBindValue(value.second);
  qry.addBindValue(value.first);
  qry.exec&#40;&#41;;
}&#41;;

}
@

I could update and add the data into the table separately, what if I like to
update and insert the data into the table simultaneous?

assume the data of the table are
Original table :
address number
one 1
two 2
three 3

the data of the std::map are
address number
one 100
two 200
three 300
four 400

now I would like to synchronous the data of the database and the std::map
Currently I do like this
@
add_message_number(data);
update_message_number(data);
@

Do I have a better choice?Thanks

lgeyer

If I have understood you correctly (you want to insert data into the table, and if the data already exists it should be updated) you can use non-standard <code>REPLACE INTO</code> (at least if you are on MySQL or SQLite, there might be a similar command in other DBMSs).

stereomatching

Thanks, I study SQL from W3C but haven't find out there are something like "REPLACE INTO"
Maybe it is because this is a non-standard instruction?

lgeyer

Yes, this is a non-standard extension specific to some DBMSs.