How to: Set the File Mode when Opening a Database with OLE DB (Programmatically)
In this topic, you will learn how to set the file mode when opening a Microsoft SQL Server 2005 Compact Edition (SQL Server Compact Edition) database by using the OLE DB provider for SQL Server Compact Edition. To set the mode in which the database is opened, you use the DBPROP_INIT_MODE property. The following table defines the valid values for the file mode:
Value | Definition |
---|---|
DB_MODE_READ |
Lets you open a read-only copy of the database. |
DB_MODE_WRITE |
Lets you open a write-only copy of the database. |
DB_MODE_READWRITE |
Permits multiple processes to open and modify the database. |
DB_MODE_SHARE_DENY_READ |
Prevents others from opening in read mode. |
DB_MODE_SHARE_DENY_WRITE |
Prevents others from opening in write mode. |
DB_MODE_SHARE_EXCLUSIVE |
Prevents others from opening in read/write mode (DB_MODE_SHARE_DENY_READ | DB_MODE_SHARE_DENY_WRITE). |
DB_MODE_SHARE_DENY_NONE |
Neither read nor write access can be denied to others. |
Note
When you open a database that is located on a file share, the only option available is the DB_MODE_SHARE_EXCLUSIVE file mode. Reading and writing a SQL Server Compact Edition database over a network share works only from one process. Within that one process, multiple connections can be opened. For example, one connection can perform an Insert operation and a second connection can perform a Select query. However, two separate connections cannot use SQL Server Compact Edition to access the same .sdf file over a network share. The second connection will receive a file-sharing violation error.
Example
The following code shows how to set the file mode by using the OLE DB provider for SQL Server Compact Edition.
DBPROPSETdbpropset[1]; // Property Set used to initialize provider
DBPROPdbprop[2]; // Property array used in property set to initialize provider
VariantInit(&dbprop[0].vValue);
VariantInit(&dbprop[1].vValue);
// Initialize property with name of database
dbprop[0].dwPropertyID = DBPROP_INIT_DATASOURCE;
dbprop[0].dwOptions = DBPROPOPTIONS_REQUIRED;
dbprop[0].vValue.vt = VT_BSTR;
dbprop[0].vValue.bstrVal = SysAllocString(L"MyDB.sdf");
if(NULL == dbprop[0].vValue.bstrVal)
{
hr = E_OUTOFMEMORY;
goto Exit;
}
// Initialize property with open mode for database
dbprop[1].dwPropertyID = DBPROP_INIT_MODE;
dbprop[1].dwOptions = DBPROPOPTIONS_REQUIRED;
dbprop[1].vValue.vt = VT_I4;
dbprop[1].vValue.lVal = DB_MODE_READ;
// Initialize property set
dbpropset[0].guidPropertySet = DBPROPSET_DBINIT;
dbpropset[0].rgProperties = dbprop;
dbpropset[0].cProperties = sizeof(dbprop)/sizeof(dbprop[0]);
// Set properties into the provider's DSO object
hr = pIDBProperties->SetProperties(sizeof(dbpropset)/sizeof(dbpropset[0]), dbpropset);
if(FAILED(hr))
{
goto Exit;
}