[ZEPPELIN-2279] excluded comments from SQL

jdbc/src/main/java/org/apache/zeppelin/jdbc/JDBCInterpreter.java

@@ -506,19 +506,36 @@ private boolean isDDLCommand(int updatedCount, int columnCount) throws SQLExcept
   protected ArrayList<String> splitSqlQueries(String sql) {
     ArrayList<String> queries = new ArrayList<>();
     StringBuilder query = new StringBuilder();
-    Character character;
+    char character;
 
     Boolean antiSlash = false;
+    Boolean multiLineComment = false;
+    Boolean singleLineComment = false;
     Boolean quoteString = false;
     Boolean doubleQuoteString = false;
 
     for (int item = 0; item < sql.length(); item++) {
       character = sql.charAt(item);
 
-      if (character.equals('\\')) {
+      if ((singleLineComment && (character == '\n' || item == sql.length() - 1))
+          || (multiLineComment && character == '/' && sql.charAt(item - 1) == '*')) {
+        singleLineComment = false;
+        multiLineComment = false;
+        if (item == sql.length() - 1 && query.length() > 0) {
+          queries.add(StringUtils.trim(query.toString()));
+        }
+        continue;
+      }
+
+      if (singleLineComment || multiLineComment) {
+        continue;
+      }
+
+      if (character == '\\') {
         antiSlash = true;
       }
-      if (character.equals('\'')) {
+
+      if (character == '\'') {
         if (antiSlash) {
           antiSlash = false;
         } else if (quoteString) {
@@ -527,7 +544,8 @@ protected ArrayList<String> splitSqlQueries(String sql) {
           quoteString = true;
         }
       }
-      if (character.equals('"')) {
+
+      if (character == '"') {
         if (antiSlash) {
           antiSlash = false;
         } else if (doubleQuoteString) {
@@ -537,16 +555,30 @@ protected ArrayList<String> splitSqlQueries(String sql) {
         }
       }
 
-      if (character.equals(';') && !antiSlash && !quoteString && !doubleQuoteString) {
-        queries.add(query.toString());
+      if (!quoteString && !doubleQuoteString && !multiLineComment && !singleLineComment
+          && sql.length() > item + 1) {
+        if (character == '-' && sql.charAt(item + 1) == '-') {
+          singleLineComment = true;
+          continue;
+        }
+
+        if (character == '/' && sql.charAt(item + 1) == '*') {
+          multiLineComment = true;
+          continue;
+        }
+      }
+
+      if (character == ';' && !antiSlash && !quoteString && !doubleQuoteString) {
+        queries.add(StringUtils.trim(query.toString()));
         query = new StringBuilder();
       } else if (item == sql.length() - 1) {
         query.append(character);
-        queries.add(query.toString());
+        queries.add(StringUtils.trim(query.toString()));
       } else {
         query.append(character);
       }
     }
+
     return queries;
   }
 

jdbc/src/test/java/org/apache/zeppelin/jdbc/JDBCInterpreterTest.java

@@ -448,4 +448,32 @@ public void testPrecodeWithAnotherPrefix() throws SQLException, IOException {
     assertEquals(InterpreterResult.Type.TABLE, interpreterResult.message().get(0).getType());
     assertEquals("@TESTVARIABLE\n2\n", interpreterResult.message().get(0).getData());
   }
+
+  @Test
+  public void testExcludingComments() throws SQLException, IOException {
+    Properties properties = new Properties();
+    properties.setProperty("common.max_count", "1000");
+    properties.setProperty("common.max_retry", "3");
+    properties.setProperty("default.driver", "org.h2.Driver");
+    properties.setProperty("default.url", getJdbcConnection());
+    properties.setProperty("default.user", "");
+    properties.setProperty("default.password", "");
+    JDBCInterpreter t = new JDBCInterpreter(properties);
+    t.open();
+
+    String sqlQuery = "/* ; */\n" +
+        "-- /* comment\n" +
+        "--select * from test_table\n" +
+        "select * from test_table; /* some comment ; */\n" +
+        "/*\n" +
+        "select * from test_table;\n" +
+        "*/\n" +
+        "-- a ; b\n" +
+        "select * from test_table WHERE ID = ';--';\n" +
+        "select * from test_table WHERE ID = '/*' -- test";
+
+    InterpreterResult interpreterResult = t.interpret(sqlQuery, interpreterContext);
+    assertEquals(InterpreterResult.Code.SUCCESS, interpreterResult.code());
+    assertEquals(3, interpreterResult.message().size());
+  }
 }