Split transaction statement into two commands. Fixes #774

Author: bgrainger

src/MySqlConnector/Core/StandardEnlistedTransaction.cs

@@ -29,8 +29,11 @@ protected override void OnStart()
 				_ => "repeatable read",
 			};
 
-			var consistentSnapshotText = Transaction.IsolationLevel == IsolationLevel.Snapshot ? " with consistent snapshot" : string.Empty;
-			using var cmd = new MySqlCommand($"set transaction isolation level {isolationLevel}; start transaction{consistentSnapshotText};", Connection);
+			using var cmd = new MySqlCommand($"set transaction isolation level {isolationLevel};", Connection);
+			cmd.ExecuteNonQuery();
+
+			var consistentSnapshotText = Transaction.IsolationLevel == IsolationLevel.Snapshot ? " with consistent snapshot" : "";
+			cmd.CommandText = $"start transaction{consistentSnapshotText};";
 			cmd.ExecuteNonQuery();
 		}
 

src/MySqlConnector/MySql.Data.MySqlClient/MySqlConnection.cs

@@ -57,7 +57,7 @@ private async ValueTask<MySqlTransaction> BeginDbTransactionAsync(IsolationLevel
 				throw new InvalidOperationException("Cannot begin a transaction when already enlisted in a transaction.");
 #endif
 
-			string isolationLevelValue = isolationLevel switch
+			var isolationLevelValue = isolationLevel switch
 			{
 				IsolationLevel.ReadUncommitted => "read uncommitted",
 				IsolationLevel.ReadCommitted => "read committed",
@@ -71,10 +71,14 @@ private async ValueTask<MySqlTransaction> BeginDbTransactionAsync(IsolationLevel
 				_ => throw new NotSupportedException("IsolationLevel.{0} is not supported.".FormatInvariant(isolationLevel))
 			};
 
-			var consistentSnapshotText = isolationLevel == IsolationLevel.Snapshot ? " with consistent snapshot" : string.Empty;
+			using (var cmd = new MySqlCommand($"set transaction isolation level {isolationLevelValue};", this))
+			{
+				await cmd.ExecuteNonQueryAsync(ioBehavior, cancellationToken).ConfigureAwait(false);
 
-			using (var cmd = new MySqlCommand($"set transaction isolation level {isolationLevelValue}; start transaction{consistentSnapshotText};", this))
+				var consistentSnapshotText = isolationLevel == IsolationLevel.Snapshot ? " with consistent snapshot" : "";
+				cmd.CommandText = $"start transaction{consistentSnapshotText};";
 				await cmd.ExecuteNonQueryAsync(ioBehavior, cancellationToken).ConfigureAwait(false);
+			}
 
 			var transaction = new MySqlTransaction(this, isolationLevel);
 			CurrentTransaction = transaction;

tests/SideBySide/Transaction.cs

@@ -94,7 +94,7 @@ public void DbConnectionTransactionCommand(IsolationLevel inputIsolationLevel, s
 			using (var trans = connection.BeginTransaction(inputIsolationLevel))
 				trans.Commit();
 
-			var results = connection.Query<string>($"select convert(argument USING utf8) from mysql.general_log where thread_id = @ServerThread and convert(argument using utf8) like '%start transaction%' and argument not like 'select%' order by event_time;", new { m_connection.ServerThread });
+			var results = connection.Query<string>($"select convert(argument USING utf8) from mysql.general_log where thread_id = @ServerThread and convert(argument using utf8) like 'start transaction%' order by event_time;", new { m_connection.ServerThread });
 			var lastStartTransactionQuery = results.Last();
 
 			Assert.Contains(expectedTransactionIsolationLevel.ToLower(), lastStartTransactionQuery.ToLower());