/// <summary>
/// Constructs the transaction object, binding it to the supplied connection
/// </summary>
/// <param name="connection">The connection to open a transaction on</param>
/// <param name="deferredLock">TRUE to defer the writelock, or FALSE to lock immediately</param>
internal SQLiteTransaction(SQLiteConnection connection, bool deferredLock)
{
_cnn = connection;
_version = _cnn._version;
_level = (deferredLock == true) ?
SQLiteConnection.DeferredIsolationLevel :
SQLiteConnection.ImmediateIsolationLevel;
if (_cnn._transactionLevel++ == 0)
{
try
{
using (SQLiteCommand cmd = _cnn.CreateCommand())
{
if (!deferredLock)
cmd.CommandText = "BEGIN IMMEDIATE";
else
cmd.CommandText = "BEGIN";
cmd.ExecuteNonQuery();
}
}
catch (SQLiteException)
{
_cnn._transactionLevel--;
_cnn = null;
throw;
}
}
}
internal KeyQuery(SQLiteConnection cnn, string database, string table, params string[] columns)
{
using (SQLiteCommandBuilder builder = new SQLiteCommandBuilder())
{
_command = cnn.CreateCommand();
for (int n = 0; n < columns.Length; n++)
{
columns[n] = builder.QuoteIdentifier(columns[n]);
}
}
_command.CommandText = String.Format(CultureInfo.InvariantCulture, "SELECT {0} FROM [{1}].[{2}] WHERE ROWID = ?", String.Join(",", columns), database, table);
_command.Parameters.AddWithValue(null, (long)0);
}
/// <summary>
/// This method creates a new connection, executes the query using the given
/// execution type and command behavior, closes the connection, and returns
/// the results. If the connection string is null, a temporary in-memory
/// database connection will be used.
/// </summary>
/// <param name="commandText">
/// The text of the command to be executed.
/// </param>
/// <param name="executeType">
/// The execution type for the command. This is used to determine which method
/// of the command object to call, which then determines the type of results
/// returned, if any.
/// </param>
/// <param name="commandBehavior">
/// The command behavior flags for the command.
/// </param>
/// <param name="connectionString">
/// The connection string to the database to be opened, used, and closed. If
/// this parameter is null, a temporary in-memory databse will be used.
/// </param>
/// <param name="args">
/// The SQL parameter values to be used when building the command object to be
/// executed, if any.
/// </param>
/// <returns>
/// The results of the query -OR- null if no results were produced from the
/// given execution type.
/// </returns>
public static object Execute(
string commandText,
SQLiteExecuteType executeType,
CommandBehavior commandBehavior,
string connectionString,
params object[] args
)
{
if (connectionString == null)
connectionString = DefaultConnectionString;
using (SQLiteConnection connection = new SQLiteConnection(connectionString))
{
connection.Open();
using (SQLiteCommand command = connection.CreateCommand())
{
command.CommandText = commandText;
if (args != null)
{
foreach (object arg in args)
{
if (arg is SQLiteParameter)
command.Parameters.Add((SQLiteParameter)arg);
else
command.Parameters.Add(new SQLiteParameter(DbType.Object, arg));
}
}
switch (executeType)
{
case SQLiteExecuteType.None:
{
//
// NOTE: Do nothing.
//
break;
}
case SQLiteExecuteType.NonQuery:
{
return command.ExecuteNonQuery(commandBehavior);
}
case SQLiteExecuteType.Scalar:
{
return command.ExecuteScalar(commandBehavior);
}
case SQLiteExecuteType.Reader:
{
return command.ExecuteReader(commandBehavior);
}
}
}
}
return null;
}
