qXwhk0at

1open existing sqlite3 database under QT
2void MainWindow::func()
3{
4    QSqlQuery query;
5    accounts_db = new QSqlDatabase();
6    *accounts_db = QSqlDatabase::addDatabase("QSQLITE");
7    perror("? ");
8accounts_db->setDatabaseName("/home/user/xyz.db");
9QSqlError *a = new QSqlError();
10*a = accounts_db->lastError();
11perror(a->text().toLatin1());
12if (!accounts_db->open()) {
13    perror("database open error :");
14}
15if ( !accounts_db->isOpen() ) {
16    perror("database is not open");
17}
18query.exec("select accno,branchcode,fname,lname,curbalance,accdate from accounts");
19while(query.next()) {
20    QString str = query.value(0).toString();
21    std::cerr << qPrintable(str) << std::endl;
22}
23end:
24;
25}
26	
27No such file or directory
28: Invalid argument
29QSqlQuery::exec: database not open
30	
31QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE", "connection_name");
32// Open db...
33QSqlQuery query(db);
34if (!query.exec(...)) {
35   // ...
36}
37// ...
38	
39#include <QSqlDatabase>
40#include <QSqlQuery>
41#include <QSqlError>
42#include <QVariant>
43
44int main(int argc, char *argv[])
45{
46    // Create database.
47    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE", "Connection");
48    db.setDatabaseName("/tmp/test.db");
49    if (!db.open()) {
50        qDebug("Error occurred opening the database.");
51        qDebug("%s.", qPrintable(db.lastError().text()));
52        return -1;
53    }
54
55    // Insert table.
56    QSqlQuery query(db);
57    query.prepare("CREATE TABLE IF NOT EXISTS test (id INTEGER PRIMARY KEY, text TEXT)");
58    if (!query.exec()) {
59        qDebug("Error occurred creating table.");
60        qDebug("%s.", qPrintable(db.lastError().text()));
61        return -1;
62    }
63
64    // Insert row.
65    query.prepare("INSERT INTO test VALUES (null, ?)");
66    query.addBindValue("Some text");
67    if (!query.exec()) {
68        qDebug("Error occurred inserting.");
69        qDebug("%s.", qPrintable(db.lastError().text()));
70        return -1;
71    }
72
73    // Query.
74    query.prepare("SELECT * FROM test");
75    if (!query.exec()) {
76        qDebug("Error occurred querying.");
77        qDebug("%s.", qPrintable(db.lastError().text()));
78        return -1;
79    }
80    while (query.next()) {
81        qDebug("id = %d, text = %s.", query.value(0).toInt(),
82               qPrintable(query.value(1).toString()));
83    }
84
85    return 0;
86}
87	
88void MainWindow::func()
89{
90    // Note: no pointer!
91    QSqlDatabase accounts_db = QSqlDatabase::addDatabase("QSQLITE");
92    accounts_db.setDatabaseName("/home/user/xyz.db");
93    if (!accounts_db.open())
94    {
95        qDebug() << "Could not open database file:";
96        qDebug() << accounts_db.lastError();
97        return;
98    }
99    // Note: don't construct queries before you have a database!
100    QSqlQuery query;
101    if (!query.exec("select accno,branchcode,fname,lname,curbalance,accdate from accounts"))   
102    {
103        qDebug() << "Query failed:";
104        qDebug() << query.lastError();
105        return;
106    }
107    while(query.next()) {
108      QString str = query.value(0).toString();
109      std::cerr << qPrintable(str) << std::endl;
110    }
111}
112	
113QSqlError *a = new QSqlError();
114
115accounts_db = new QSqlDatabase();
116*accounts_db = QSqlDatabase::addDatabase("QSQLITE");
117
118accounts_db->setDatabaseName("/home/user/test.db");
119
120if ( !accounts_db->open() ) {
121    qDebug() << accounts_db->lastError();
122    qDebug() << "Could not open database file:";
123}
124QSqlQuery query;
125
126if ( !(accounts_db->isOpen()) ) {
127    qDebug() << accounts_db->lastError();
128    qDebug() << ": Could not open database file:";
129    goto end;   // quit if not successful
130}
131
132query.exec("select * from accounts");
133
134while(query.next()) {
135    // loop for i columns
136    QString str = query.value(i).toString();
137    std::cerr << qPrintable(str) << std::endl ;
138    // loop
139}
140end:
141;