diff --git a/source/libs/parser/src/parTranslater.c b/source/libs/parser/src/parTranslater.c
index b1580c3a516d9331a45f6a6b47e16bdfbc44d2ed..be472781039485aaee04b93646823db28ca885b8 100644
--- a/source/libs/parser/src/parTranslater.c
+++ b/source/libs/parser/src/parTranslater.c
@@ -783,6 +783,13 @@ static EDealRes translateValueImpl(STranslateContext* pCxt, SValueNode* pVal, SD
   if (pVal->placeholderNo > 0 || pVal->isNull) {
     return DEAL_RES_CONTINUE;
   }
+  if (TSDB_DATA_TYPE_NULL == pVal->node.resType.type) {
+    // TODO 
+    //pVal->node.resType = targetDt;
+    pVal->translate = true;
+    pVal->isNull = true;
+    return DEAL_RES_CONTINUE;
+  }  
   if (pVal->isDuration) {
     if (parseNatualDuration(pVal->literal, strlen(pVal->literal), &pVal->datum.i, &pVal->unit, precision) !=
         TSDB_CODE_SUCCESS) {
@@ -5355,7 +5362,7 @@ static int32_t buildKVRowForAllTags(STranslateContext* pCxt, SCreateSubTableClau
       if (code != TSDB_CODE_SUCCESS) {
         goto end;
       }
-    } else if (pVal->node.resType.type != TSDB_DATA_TYPE_NULL) {
+    } else if (pVal->node.resType.type != TSDB_DATA_TYPE_NULL && !pVal->isNull) {
       char*   tmpVal = nodesGetValueFromNode(pVal);
       STagVal val = {.cid = pTagSchema->colId, .type = pTagSchema->type};
       if (IS_VAR_DATA_TYPE(pTagSchema->type)) {
@@ -5622,8 +5629,8 @@ static int32_t buildUpdateTagValReq(STranslateContext* pCxt, SAlterTableStmt* pS
     return TSDB_CODE_OUT_OF_MEMORY;
   }
 
-  if (DEAL_RES_ERROR ==
-      translateValueImpl(pCxt, pStmt->pVal, schemaToDataType(pTableMeta->tableInfo.precision, pSchema))) {
+  SDataType targetDt = schemaToDataType(pTableMeta->tableInfo.precision, pSchema);
+  if (DEAL_RES_ERROR == translateValueImpl(pCxt, pStmt->pVal, targetDt)) {
     return pCxt->errCode;
   }
 
@@ -5632,7 +5639,8 @@ static int32_t buildUpdateTagValReq(STranslateContext* pCxt, SAlterTableStmt* pS
   }
 
   pReq->isNull = (TSDB_DATA_TYPE_NULL == pStmt->pVal->node.resType.type);
-  if (pStmt->pVal->node.resType.type == TSDB_DATA_TYPE_JSON) {
+  if (targetDt.type == TSDB_DATA_TYPE_JSON) {
+    pReq->isNull = 0;
     if (pStmt->pVal->literal &&
         strlen(pStmt->pVal->literal) > (TSDB_MAX_JSON_TAG_LEN - VARSTR_HEADER_SIZE) / TSDB_NCHAR_SIZE) {
       return buildSyntaxErrMsg(&pCxt->msgBuf, "json string too long than 4095", pStmt->pVal->literal);