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//! [0]
# WRONG
db = QSqlDatabase.database("sales")
query = QSqlQuery("SELECT NAME, DOB FROM EMPLOYEES", db)
QSqlDatabase.removeDatabase("sales") # will output a warning

# "db" is now a dangling invalid database connection,
# "query" contains an invalid result set
//! [0]


//! [1]
db = QSqlDatabase.database("sales")
query = QSqlQuery("SELECT NAME, DOB FROM EMPLOYEES", db)
# Both "db" and "query" are destroyed because they are out of scope
QSqlDatabase.removeDatabase("sales") # correct
//! [1]


//! [2]
class MyDatabaseDriverCreatorBase(QtSql.QSqlDriverCreatorBase):
    ...
    def createObject(self):
        return MyDatabaseDriver()

mydriver = MyDatabaseDriverCreatorBase()
QtSql.QSqlDatabase.registerSqlDriver("MYDRIVER", mydriver)
db = QtSql.QSqlDatabase.addDatabase("MYDRIVER")
//! [2]


//! [3]
...
db = QSqlDatabase.addDatabase("QODBC")
db.setDatabaseName("DRIVER={Microsoft Access Driver (*.mdb)};FIL={MS Access};DBQ=myaccessfile.mdb")
if db.open():
    # success!
    pass
...
//! [3]


//! [4]
...
# MySQL connection
db.setConnectOptions("CLIENT_SSL=1;CLIENT_IGNORE_SPACE=1") # use an SSL connection to the server
if not db.open():
    db.setConnectOptions() # clears the connect option string
    ...
...
# PostgreSQL connection
db.setConnectOptions("requiressl=1")    # enable PostgreSQL SSL connections
if not db.open():
    db.setConnectOptions() # clear options
    ...
...
# ODBC connection
# set ODBC options
db.setConnectOptions("SQL_ATTR_ACCESS_MODE=SQL_MODE_READ_ONLY;SQL_ATTR_TRACE=SQL_OPT_TRACE_ON")
if not db.open():
    db.setConnectOptions()              # don't try to set this option
    ...
//! [4]


//! [5]
#include "qtdir/src/sql/drivers/psql/qsql_psql.cpp"
//! [5]


//! [6]
con = PQconnectdb("host=server user=bart password=simpson dbname=springfield")
drv = QPSQLDriver(con)
db = QSqlDatabase.addDatabase(drv) # becomes the new default connection
query = QSqlQuery()
query.exec_("SELECT NAME, ID FROM STAFF")
...
//! [6]


//! [7]
unix:LIBS += -lpq
win32:LIBS += libpqdll.lib
//! [7]


//! [8]
db = QSqlDatabase()
print(db.isValid())         # Returns False

db = QSqlDatabase.database("sales")
print(db.isValid())         # Returns True if "sales" connection exists

QSqlDatabase.removeDatabase("sales")
print(db.isValid())         # Returns False
//! [8]