Merge pull request #47 from aminroosta/fix46

fix #46

Author: aminroosta

hdr/sqlite_modern_cpp.h

@@ -302,6 +302,14 @@ namespace sqlite {
 			return *this << std::string(sql);
 		}
 
+		database_binder::chain_type operator<<(const std::u16string& sql) {
+			return database_binder::chain_type(new database_binder(_db, sql));
+		}
+
+		database_binder::chain_type operator<<(const char16_t* sql) {
+			return *this << std::u16string(sql);
+		}
+
 		connection_type connection() const { return _db; }
 
 		sqlite3_int64 last_insert_rowid() const {

tests/readme_example.cc

@@ -0,0 +1,72 @@
+#include<iostream>
+#include <sqlite_modern_cpp.h>
+using namespace  sqlite;
+using namespace std;
+
+int main() {
+
+	try {
+		// creates a database file 'dbfile.db' if it does not exists.
+		database db(":memory:");
+
+		// executes the query and creates a 'user' table
+		db <<
+			"create table if not exists user ("
+			"   _id integer primary key autoincrement not null,"
+			"   age int,"
+			"   name text,"
+			"   weight real"
+			");";
+
+		// inserts a new user record.
+		// binds the fields to '?' .
+		// note that only types allowed for bindings are :
+		//      int ,long, long long, float, double
+		//      string , u16string
+		// sqlite3 only supports utf8 and utf16 strings, you should use std::string for utf8 and std::u16string for utf16.
+		// note that u"my text" is a utf16 string literal of type char16_t * .
+		db << "insert into user (age,name,weight) values (?,?,?);"
+			<< 20
+			<< u"bob"
+			<< 83.25;
+
+		int age = 21;
+		float weight = 68.5;
+		string name = "jack";
+		db << u"insert into user (age,name,weight) values (?,?,?);" // utf16 query string
+			<< age
+			<< name
+			<< weight;
+
+		cout << "The new record got assigned id " << db.last_insert_rowid() << endl;
+
+		// slects from user table on a condition ( age > 18 ) and executes
+		// the lambda for each row returned .
+		db << "select age,name,weight from user where age > ? ;"
+			<< 18
+			>> [&](int age, string name, double weight) {
+			cout << age << ' ' << name << ' ' << weight << endl;
+		};
+
+		// selects the count(*) from user table
+		// note that you can extract a single culumn single row result only to : int,long,long,float,double,string,u16string
+		int count = 0;
+		db << "select count(*) from user" >> count;
+		cout << "cout : " << count << endl;
+
+		// you can also extract multiple column rows
+		db << "select age, name from user where _id=1;" >> tie(age, name);
+		cout << "Age = " << age << ", name = " << name << endl;
+
+		// this also works and the returned value will be automatically converted to string
+		string str_count;
+		db << "select count(*) from user" >> str_count;
+		cout << "scount : " << str_count << endl;
+	}
+	catch (exception& e) {
+		cerr << e.what() << endl;
+		exit(EXIT_FAILURE);
+	}
+
+  return 0;
+}