144 lines
3.3 KiB
C++
144 lines
3.3 KiB
C++
//
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// This example is implemented from here https://www.tutorialspoint.com/sqlite/sqlite_distinct_keyword.htm
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//
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#include <sqlite_orm/sqlite_orm.h>
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#include <iostream>
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using std::cout;
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using std::endl;
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struct Employee {
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int id;
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std::string name;
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int age;
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std::string address;
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double salary;
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};
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auto initStorage(const std::string& path) {
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using namespace sqlite_orm;
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return make_storage(path,
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make_table("COMPANY",
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make_column("ID", &Employee::id, primary_key()),
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make_column("NAME", &Employee::name),
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make_column("AGE", &Employee::age),
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make_column("ADDRESS", &Employee::address),
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make_column("SALARY", &Employee::salary)));
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}
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using Storage = decltype(initStorage(""));
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int main(int, char**) {
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Storage storage = initStorage("distinct.sqlite");
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// sync schema in case this is a very first launch
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storage.sync_schema();
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// remove all employees if it is not the very first launch
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storage.remove_all<Employee>();
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// now let's insert start values to wirk with. We'll make it within a transaction
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// for better perfomance
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storage.begin_transaction();
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storage.insert(Employee{
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-1,
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"Paul",
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32,
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"California",
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20000.0,
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});
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storage.insert(Employee{
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-1,
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"Allen",
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25,
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"Texas",
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15000.0,
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});
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storage.insert(Employee{
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-1,
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"Teddy",
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23,
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"Norway",
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20000.0,
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});
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storage.insert(Employee{
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-1,
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"Mark",
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25,
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"Rich-Mond",
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65000.0,
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});
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storage.insert(Employee{
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-1,
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"David",
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27,
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"Texas",
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85000.0,
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});
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storage.insert(Employee{
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-1,
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"Kim",
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22,
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"South-Hall",
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45000.0,
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});
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storage.insert(Employee{
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-1,
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"James",
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24,
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"Houston",
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10000.0,
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});
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storage.insert(Employee{
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-1,
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"Paul",
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24,
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"Houston",
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20000.0,
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});
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storage.insert(Employee{
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-1,
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"James",
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44,
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"Norway",
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5000.0,
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});
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storage.insert(Employee{
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-1,
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"James",
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45,
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"Texas",
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5000.0,
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});
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storage.commit();
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// SELECT 'NAME' FROM 'COMPANY'
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auto pureNames = storage.select(&Employee::name);
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cout << "NAME" << endl;
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cout << "----------" << endl;
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for(auto& name: pureNames) {
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cout << name << endl;
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}
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cout << endl;
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using namespace sqlite_orm;
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// SELECT DISTINCT 'NAME' FROM 'COMPANY'
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auto distinctNames = storage.select(distinct(&Employee::name));
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cout << "NAME" << endl;
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cout << "----------" << endl;
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for(auto& name: distinctNames) {
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cout << name << endl;
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}
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cout << endl;
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// SELECT DISTINCT 'ADDRESS', 'NAME' FROM 'COMPANY'
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auto severalColumns = storage.select(distinct(columns(&Employee::address, &Employee::name)));
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cout << "ADDRESS" << '\t' << "NAME" << endl;
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cout << "----------" << endl;
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for(auto& t: severalColumns) {
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cout << std::get<0>(t) << '\t' << std::get<1>(t) << endl;
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}
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return 0;
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}
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