/// <summary>
/// Fetches the next sequential record from the view, or null if there are no more records.
/// </summary>
/// <exception cref="InstallerException">the View is not in an active state</exception>
/// <exception cref="InvalidHandleException">the View handle is invalid</exception>
/// <remarks><p>
/// The Record object should be <see cref="InstallerHandle.Close"/>d after use.
/// It is best that the handle be closed manually as soon as it is no longer
/// needed, as leaving lots of unused handles open can degrade performance.
/// </p><p>
/// Win32 MSI API:
/// <a href="http://msdn.microsoft.com/library/en-us/msi/setup/msiviewfetch.asp">MsiViewFetch</a>
/// </p></remarks>
public Record Fetch()
{
int recordHandle;
uint ret = RemotableNativeMethods.MsiViewFetch((int)this.Handle, out recordHandle);
if (ret == (uint)NativeMethods.Error.NO_MORE_ITEMS)
{
return(null);
}
else if (ret != 0)
{
throw InstallerException.ExceptionFromReturnCode(ret);
}
Record r = new Record((IntPtr)recordHandle, true, this);
r.IsFormatStringInvalid = true;
return(r);
}
/// <summary>
/// Gets the count of all rows in the table that satisfy a given condition.
/// </summary>
/// <param name="table">Name of the table whose rows are to be counted</param>
/// <param name="where">Conditional expression, such as could be placed on the end of a SQL WHERE clause</param>
/// <returns>The count of all rows in the table satisfying the condition</returns>
/// <exception cref="BadQuerySyntaxException">the SQL WHERE syntax is invalid</exception>
/// <exception cref="InstallerException">the View could not be executed</exception>
/// <exception cref="InvalidHandleException">the Database handle is invalid</exception>
public int CountRows(string table, string where)
{
if (string.IsNullOrWhiteSpace(table))
{
throw new ArgumentNullException("table");
}
int count;
using (View view = this.OpenView(
"SELECT `{0}` FROM `{1}`{2}",
this.Tables[table].PrimaryKeys[0],
table,
(where != null && where.Length != 0 ? " WHERE " + where : "")))
{
view.Execute();
for (count = 0; ; count++)
{
// Avoid creating unnecessary Record objects by not calling View.Fetch().
int recordHandle;
uint ret = RemotableNativeMethods.MsiViewFetch((int)view.Handle, out recordHandle);
if (ret == (uint)NativeMethods.Error.NO_MORE_ITEMS)
{
break;
}
if (ret != 0)
{
throw InstallerException.ExceptionFromReturnCode(ret);
}
RemotableNativeMethods.MsiCloseHandle(recordHandle);
}
}
return(count);
}
