fix coverity error

src/client/src/TSDBJNIConnector.c

@@ -228,11 +228,9 @@ JNIEXPORT jlong JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_connectImp(JNIEn
 
   if (user == NULL) {
     jniTrace("jobj:%p, user is null, use default user %s", jobj, TSDB_DEFAULT_USER);
-    user = TSDB_DEFAULT_USER;
   }
   if (pass == NULL) {
     jniTrace("jobj:%p, pass is null, use default password", jobj);
-    pass = TSDB_DEFAULT_PASS;
   }
 
   /*
@@ -252,8 +250,8 @@ JNIEXPORT jlong JNICALL Java_com_taosdata_jdbc_TSDBJNIConnector_connectImp(JNIEn
 
   if (host != NULL) (*env)->ReleaseStringUTFChars(env, jhost, host);
   if (dbname != NULL) (*env)->ReleaseStringUTFChars(env, jdbName, dbname);
-  if (user != NULL && user != (const char *)TSDB_DEFAULT_USER) (*env)->ReleaseStringUTFChars(env, juser, user);
-  if (pass != NULL && pass != (const char *)TSDB_DEFAULT_PASS) (*env)->ReleaseStringUTFChars(env, jpass, pass);
+  if (user != NULL) (*env)->ReleaseStringUTFChars(env, juser, user);
+  if (pass != NULL) (*env)->ReleaseStringUTFChars(env, jpass, pass);
 
   return ret;
 }

src/client/src/tscSql.c

@@ -147,6 +147,8 @@ static void syncConnCallback(void *param, TAOS_RES *tres, int code) {
 
 TAOS *taos_connect(const char *ip, const char *user, const char *pass, const char *db, uint16_t port) {
   tscTrace("try to create a connection to %s:%u, user:%s db:%s", ip, port, user, db);
+  if (user == NULL) user = TSDB_DEFAULT_USER;
+  if (pass == NULL) pass = TSDB_DEFAULT_PASS;
 
   STscObj* pObj = NULL;
   SSqlObj *pSql = taosConnectImpl(ip, user, pass, db, port, syncConnCallback, NULL, (void**) &pObj);