[TD-2286]<fix>: fix wrong error info when use unexisted database

tests/examples/JDBC/JDBCDemo/pom.xml

@@ -48,4 +48,12 @@
         </plugins>
     </build>
 
+    <dependencies>
+        <dependency>
+            <groupId>com.taosdata.jdbc</groupId>
+            <artifactId>taos-jdbcdriver</artifactId>
+            <version>2.0.15</version>
+        </dependency>
+    </dependencies>
+
 </project>

tests/examples/JDBC/JDBCDemo/src/main/java/com/taosdata/example/JDBCDemo.java

@@ -21,7 +21,7 @@ public class JDBCDemo {
             }
         }
 
-        if (host == null || driverType == null) {
+        if (host == null) {
             printHelp();
         }