DataReader: do not throw exception on empty dataset #58

DarkWanderer · Jan 16, 2021 · 6675910 · 6675910
1 parent ecf5441
commit 6675910
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Showing 2 changed files with 9 additions and 2 deletions.
diff --git a/ClickHouse.Client.Tests/SqlAlterTests.cs b/ClickHouse.Client.Tests/SqlAlterTests.cs
@@ -21,8 +21,8 @@ public SqlAlterTests()
         [Test]
         public async Task ShouldExecuteAlterTable()
         {
-            await connection.ExecuteStatementAsync($"CREATE TABLE IF NOT EXISTS test.table_delete_from (value Int32) ENGINE=MergeTree ORDER BY value");
-            await connection.ExecuteStatementAsync($"ALTER TABLE test.table_delete_from DELETE WHERE 1=1");
+            await connection.ExecuteScalarAsync($"CREATE TABLE IF NOT EXISTS test.table_delete_from (value Int32) ENGINE=MergeTree ORDER BY value");
+            await connection.ExecuteScalarAsync($"ALTER TABLE test.table_delete_from DELETE WHERE 1=1");
         }
     }
 }
diff --git a/ClickHouse.Client/ADO/Readers/ClickHouseDataReader.cs b/ClickHouse.Client/ADO/Readers/ClickHouseDataReader.cs
@@ -161,6 +161,13 @@ protected override void Dispose(bool disposing)
 
         private void ReadHeaders()
         {
+            if (reader.PeekChar() == -1)
+            {
+                // Empty dataset
+                FieldNames = new string[0];
+                RawTypes = new ClickHouseType[0];
+                return;
+            }
             var count = reader.Read7BitEncodedInt();
             FieldNames = new string[count];
             RawTypes = new ClickHouseType[count];