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50#include <QSqlDatabase>
51#include <QSqlQuery>
52#include <QSqlDriver>
53#include <QDebug>
54
55void openDatabase()
56{
57//! [0]
58// WRONG
59QSqlDatabase db = QSqlDatabase::database(connectionName: "sales");
60QSqlQuery query("SELECT NAME, DOB FROM EMPLOYEES", db);
61QSqlDatabase::removeDatabase(connectionName: "sales"); // will output a warning
62// "db" is now a dangling invalid database connection,
63// "query" contains an invalid result set
64//! [0]
65}
66
67void removeDatabase()
68{
69//! [1]
70{
71 QSqlDatabase db = QSqlDatabase::database(connectionName: "sales");
72 QSqlQuery query("SELECT NAME, DOB FROM EMPLOYEES", db);
73}
74// Both "db" and "query" are destroyed because they are out of scope
75QSqlDatabase::removeDatabase(connectionName: "sales"); // correct
76//! [1]
77}
78
79void setmyDatabase()
80{
81//! [3]
82// ...
83QSqlDatabase db = QSqlDatabase::addDatabase(type: "QODBC");
84db.setDatabaseName("DRIVER={Microsoft Access Driver (*.mdb, *.accdb)};FIL={MS Access};DBQ=myaccessfile.mdb");
85if (db.open()) {
86 // success!
87}
88// ...
89//! [3]
90}
91
92// ...
93// MySQL connection
94void dbConnect()
95{
96QSqlDatabase db;
97//! [4]
98db.setConnectOptions("SSL_KEY=client-key.pem;SSL_CERT=client-cert.pem;SSL_CA=ca-cert.pem;CLIENT_IGNORE_SPACE=1"); // use an SSL connection to the server
99if (!db.open()) {
100 db.setConnectOptions(); // clears the connect option string
101 // ...
102}
103// ...
104// PostgreSQL connection
105db.setConnectOptions("requiressl=1"); // enable PostgreSQL SSL connections
106if (!db.open()) {
107 db.setConnectOptions(); // clear options
108 // ...
109}
110// ...
111// ODBC connection
112db.setConnectOptions("SQL_ATTR_ACCESS_MODE=SQL_MODE_READ_ONLY;SQL_ATTR_TRACE=SQL_OPT_TRACE_ON"); // set ODBC options
113if (!db.open()) {
114 db.setConnectOptions(); // don't try to set this option
115 // ...
116}
117}
118//! [4]
119
120void dbQdebug()
121{
122//! [8]
123QSqlDatabase db;
124qDebug() << db.isValid(); // Returns false
125
126db = QSqlDatabase::database(connectionName: "sales");
127qDebug() << db.isValid(); // Returns \c true if "sales" connection exists
128
129QSqlDatabase::removeDatabase(connectionName: "sales");
130qDebug() << db.isValid(); // Returns false
131//! [8]
132}
133

source code of qtbase/src/sql/doc/snippets/code/src_sql_kernel_qsqldatabase.cpp