Fix backtick quoting for column names in batched INSERT reconstruction (#1285)

## Summary
- `generateMultiRowInsert()` now wraps column names with backticks when
reconstructing multi-row INSERT SQL
- This fixes `PARSE_SYNTAX_ERROR` for column names containing dots
(e.g., `col.name`) when `EnableBatchedInserts` is enabled
- Added test case for dotted column names

## Root Cause
`parseColumns()` strips backticks from column names, but
`generateMultiRowInsert()` joins them back without re-quoting. Unquoted
column names containing dots are then interpreted as schema/table
separators by the SQL parser.

## Test plan
- [x] Existing `InsertStatementParserTest` tests updated and passing
(18/18)
- [x] New `testGenerateMultiRowInsertWithDottedColumnNames` test added

Fixes #1284

---------

Signed-off-by: Oleksandr Shevchenko <oleksandr.shevchenko@datarobot.com>
Co-authored-by: Vikrant Puppala <vikrant.puppala@databricks.com>

Author: o-shevchenko

NEXT_CHANGELOG.md

@@ -8,6 +8,7 @@
 
 ### Fixed
 - Fixed primitive types within complex types (ARRAY, MAP, STRUCT) not being correctly parsed when Arrow serialization uses alternate formats: TIMESTAMP/TIMESTAMP_NTZ as epoch microseconds or component arrays, and BINARY as base64-encoded strings.
+- Fixed `PARSE_SYNTAX_ERROR` for column names containing special characters (e.g., dots) when `EnableBatchedInserts` is enabled, by re-quoting column names with backticks in reconstructed multi-row INSERT statements.
 
 ---
 *Note: When making changes, please add your change under the appropriate section

src/main/java/com/databricks/jdbc/common/util/InsertStatementParser.java

@@ -194,10 +194,14 @@ public static String generateMultiRowInsert(InsertInfo insertInfo, int numberOfR
     }
 
     StringBuilder sql = new StringBuilder();
+    String columnList =
+        insertInfo.getColumns().stream()
+            .map(col -> "`" + col + "`")
+            .collect(Collectors.joining(", "));
     sql.append("INSERT INTO ")
         .append(insertInfo.getTableName())
         .append(" (")
-        .append(String.join(", ", insertInfo.getColumns()))
+        .append(columnList)
         .append(") VALUES ");
 
     // Generate placeholders for each row

src/test/java/com/databricks/jdbc/api/impl/DatabricksPreparedStatementTest.java

@@ -249,7 +249,7 @@ public void testExecuteBatchStatement() throws Exception {
     }
     // Our implementation converts single INSERT to multi-row INSERT for batching
     String expectedMultiRowSQL =
-        "INSERT INTO orders (user_id, shard, region_code, namespace) VALUES (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?)";
+        "INSERT INTO orders (`user_id`, `shard`, `region_code`, `namespace`) VALUES (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?)";
     when(client.executeStatement(
             eq(expectedMultiRowSQL),
             eq(new Warehouse(WAREHOUSE_ID)),
@@ -308,7 +308,7 @@ public void testExecuteBatchStatementThrowsError() throws Exception {
 
     // Our implementation batches all into one multi-row INSERT, so if it fails, all fail
     String expectedMultiRowSQL =
-        "INSERT INTO orders (user_id, shard, region_code, namespace) VALUES (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?)";
+        "INSERT INTO orders (`user_id`, `shard`, `region_code`, `namespace`) VALUES (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?)";
     when(client.executeStatement(
             eq(expectedMultiRowSQL),
             eq(new Warehouse(WAREHOUSE_ID)),
@@ -346,7 +346,7 @@ public void testExecuteLargeBatchStatement() throws Exception {
     }
     // Our implementation converts single INSERT to multi-row INSERT for batching
     String expectedMultiRowSQL =
-        "INSERT INTO orders (user_id, shard, region_code, namespace) VALUES (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?)";
+        "INSERT INTO orders (`user_id`, `shard`, `region_code`, `namespace`) VALUES (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?)";
     when(client.executeStatement(
             eq(expectedMultiRowSQL),
             eq(new Warehouse(WAREHOUSE_ID)),
@@ -386,7 +386,7 @@ public void testExecuteLargeBatchStatementThrowsError() throws Exception {
 
     // Our implementation batches all into one multi-row INSERT, so if it fails, all fail
     String expectedMultiRowSQL =
-        "INSERT INTO orders (user_id, shard, region_code, namespace) VALUES (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?)";
+        "INSERT INTO orders (`user_id`, `shard`, `region_code`, `namespace`) VALUES (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?), (?, ?, ?, ?)";
     when(client.executeStatement(
             eq(expectedMultiRowSQL),
             eq(new Warehouse(WAREHOUSE_ID)),
@@ -962,7 +962,8 @@ public void testBatchedInsertWithManyParameters() throws Exception {
 
     // With supportManyParameters=1, all 200 rows should be batched in a single INSERT
     // with interpolated values (not parameterized)
-    String expectedSqlPrefix = "INSERT INTO orders (user_id, shard, region_code, namespace) VALUES";
+    String expectedSqlPrefix =
+        "INSERT INTO orders (`user_id`, `shard`, `region_code`, `namespace`) VALUES";
     when(client.executeStatement(
             org.mockito.ArgumentMatchers.startsWith(expectedSqlPrefix),
             eq(new Warehouse(WAREHOUSE_ID)),
@@ -1004,7 +1005,8 @@ public void testBatchedInsertWithVeryLargeParameterCount() throws Exception {
     }
 
     // With supportManyParameters=1, all 10,000 rows execute in a single INSERT
-    String expectedSqlPrefix = "INSERT INTO orders (user_id, shard, region_code, namespace) VALUES";
+    String expectedSqlPrefix =
+        "INSERT INTO orders (`user_id`, `shard`, `region_code`, `namespace`) VALUES";
     when(client.executeStatement(
             org.mockito.ArgumentMatchers.startsWith(expectedSqlPrefix),
             eq(new Warehouse(WAREHOUSE_ID)),
@@ -1048,7 +1050,8 @@ public void testBatchedInsertWithCustomBatchInsertSize() throws Exception {
     assertEquals(50, connectionContext.getBatchInsertSize());
 
     // Mock will be called 4 times (200 rows / 50 batch size = 4 chunks)
-    String expectedSqlPrefix = "INSERT INTO orders (user_id, shard, region_code, namespace) VALUES";
+    String expectedSqlPrefix =
+        "INSERT INTO orders (`user_id`, `shard`, `region_code`, `namespace`) VALUES";
     when(client.executeStatement(
             org.mockito.ArgumentMatchers.startsWith(expectedSqlPrefix),
             eq(new Warehouse(WAREHOUSE_ID)),
@@ -1108,7 +1111,8 @@ public void testBatchInsertSizeRespectsParameterLimit() throws Exception {
 
     // Without supportManyParameters, should chunk at 256/4 = 64 rows
     // even though BatchInsertSize=5000
-    String expectedSqlPrefix = "INSERT INTO orders (user_id, shard, region_code, namespace) VALUES";
+    String expectedSqlPrefix =
+        "INSERT INTO orders (`user_id`, `shard`, `region_code`, `namespace`) VALUES";
     when(client.executeStatement(
             org.mockito.ArgumentMatchers.startsWith(expectedSqlPrefix),
             eq(new Warehouse(WAREHOUSE_ID)),
@@ -1169,7 +1173,7 @@ public void testBatchedInsertWithTimestampsGeneratesQuotedSQL() throws Exception
     String executedSql = sqlCaptor.getValue();
 
     String expectedSql =
-        "INSERT INTO events (id, name, created_at) VALUES "
+        "INSERT INTO events (`id`, `name`, `created_at`) VALUES "
             + "(1, 'Event One', '2024-01-01 12:30:45.123'), "
             + "(2, 'Event Two', '2024-02-15 08:15:30.456')";
 

src/test/java/com/databricks/jdbc/common/util/InsertStatementParserTest.java

@@ -123,7 +123,8 @@ void testGenerateMultiRowInsert() throws Exception {
     assertNotNull(info);
 
     String multiRowSql = InsertStatementParser.generateMultiRowInsert(info, 3);
-    String expected = "INSERT INTO users (id, name, email) VALUES (?, ?, ?), (?, ?, ?), (?, ?, ?)";
+    String expected =
+        "INSERT INTO users (`id`, `name`, `email`) VALUES (?, ?, ?), (?, ?, ?), (?, ?, ?)";
     assertEquals(expected, multiRowSql);
   }
 
@@ -134,7 +135,7 @@ void testGenerateMultiRowInsertSingleRow() throws Exception {
     assertNotNull(info);
 
     String multiRowSql = InsertStatementParser.generateMultiRowInsert(info, 1);
-    String expected = "INSERT INTO users (id, name) VALUES (?, ?)";
+    String expected = "INSERT INTO users (`id`, `name`) VALUES (?, ?)";
     assertEquals(expected, multiRowSql);
   }
 
@@ -150,6 +151,23 @@ void testGenerateMultiRowInsertInvalidInput() {
     assertThrows(Exception.class, () -> InsertStatementParser.generateMultiRowInsert(info, -1));
   }
 
+  @Test
+  void testGenerateMultiRowInsertWithDottedColumnNames() throws Exception {
+    // Column names containing dots must be backtick-quoted to avoid being interpreted
+    // as schema.column references (see https://github.com/databricks/databricks-jdbc/issues/1284)
+    String sql =
+        "INSERT INTO `main`.`default`.`test_table` (`name`, `col.with.dots`, `another.dotted.col`) VALUES (?, ?, ?)";
+    InsertInfo info = InsertStatementParser.parseInsert(sql);
+
+    assertNotNull(info);
+    assertEquals(Arrays.asList("name", "col.with.dots", "another.dotted.col"), info.getColumns());
+
+    String multiRowSql = InsertStatementParser.generateMultiRowInsert(info, 2);
+    String expected =
+        "INSERT INTO `main`.`default`.`test_table` (`name`, `col.with.dots`, `another.dotted.col`) VALUES (?, ?, ?), (?, ?, ?)";
+    assertEquals(expected, multiRowSql);
+  }
+
   @Test
   void testInsertInfoEqualsAndHashCode() {
     InsertInfo info1 =