diff --git a/src/client/src/tscServer.c b/src/client/src/tscServer.c
index c7a24ab4e9abed681519f72872b55371f364314e..2e6cee31bf39bc26da9773433282729eb9811557 100644
--- a/src/client/src/tscServer.c
+++ b/src/client/src/tscServer.c
@@ -2657,7 +2657,8 @@ static void updateFieldForJson(SSqlObj *pSql, SQueryTableRsp *pQueryAttr){
     if (pField->field.type == TSDB_DATA_TYPE_JSON) {
       pField->fieldJson.type = TSDB_DATA_TYPE_JSON;
       for (int k = 0; k < pQueryAttr->tJsonSchLen; ++k) {
-        if (strncmp(pField->fieldJson.name, pQueryAttr->tagJsonSchema[k].name, TSDB_MAX_JSON_KEY_LEN) == 0) {
+        if (strncmp(pField->fieldJson.name, pQueryAttr->tagJsonSchema[k].name, TSDB_MAX_JSON_KEY_LEN) == 0
+            && pQueryAttr->tagJsonSchema[k].type != TSDB_DATA_TYPE_JSON) {
           pField->fieldJson.type = pQueryAttr->tagJsonSchema[k].type;
           pField->fieldJson.bytes = TYPE_BYTES[pField->field.type];
           tscDebug("0x%" PRIx64 " change json type %s:%s to %d", pSql->self, pField->field.name, pQueryAttr->tagJsonSchema[k].name,
diff --git a/src/client/src/tscUtil.c b/src/client/src/tscUtil.c
index 35c2c913d9b29a054b97eae8d3d7eb9bc1c8decc..1f5f35c4e3b12a5c2ad006f1c9ca661e37430ccf 100644
--- a/src/client/src/tscUtil.c
+++ b/src/client/src/tscUtil.c
@@ -715,11 +715,12 @@ static void setResRawPtrImpl(SSqlRes* pRes, SInternalField* pInfo, int32_t i, bo
       char* realData = p + CHAR_BYTES;
       char type = *p;
 
-      if (type == TSDB_DATA_TYPE_NCHAR && isNull(realData, TSDB_DATA_TYPE_JSON)) {
-        memcpy(dst, realData, varDataTLen(realData));
-        offset = pInfo->field.bytes;
-      }else if (type == TSDB_DATA_TYPE_NCHAR) {
-        if(convertNchar){
+      if (type == TSDB_DATA_TYPE_JSON && isNull(realData, TSDB_DATA_TYPE_JSON)) {
+        type = pInfo->fieldJson.type;
+        setNull(realData, type, 0);
+      }
+      if (type == TSDB_DATA_TYPE_NCHAR || type == TSDB_DATA_TYPE_JSON) {
+        if(convertNchar && !isNull(realData, TSDB_DATA_TYPE_NCHAR)){
           int32_t length = taosUcs4ToMbs(varDataVal(realData), varDataLen(realData), varDataVal(dst));
           varDataSetLen(dst, length);
           if (length == 0) {
@@ -729,17 +730,10 @@ static void setResRawPtrImpl(SSqlRes* pRes, SInternalField* pInfo, int32_t i, bo
           memcpy(dst, realData, varDataTLen(realData));
         }
         offset = pInfo->field.bytes;
-      }else if (type == TSDB_DATA_TYPE_DOUBLE) {
-        memcpy(dst, realData, DOUBLE_BYTES);
-        offset = DOUBLE_BYTES;
-      }else if (type == TSDB_DATA_TYPE_BIGINT) {
-        memcpy(dst, realData, LONG_BYTES);
-        offset = LONG_BYTES;
-      }else if (type == TSDB_DATA_TYPE_BOOL) {
-        memcpy(dst, realData, CHAR_BYTES);
-        offset = CHAR_BYTES;
       }else {
-        assert(0);
+        assert(type <= TSDB_DATA_TYPE_DOUBLE && type >=TSDB_DATA_TYPE_BOOL);
+        memcpy(dst, realData, tDataTypes[(int32_t)type].bytes);
+        offset = tDataTypes[(int32_t)type].bytes;
       }
 
       p += pInfo->field.bytes;
@@ -5384,7 +5378,7 @@ void* getJsonTagValueElment(STable* data, char* key, int32_t keyLen, char* dst,
   void* result = getJsonTagValue(data, keyMd5, TSDB_MAX_JSON_KEY_MD5_LEN, NULL);
   if (result == NULL){    // json key no result
     if(!dst) return NULL;
-    *(char*)dst = TSDB_DATA_TYPE_NCHAR;
+    *(char*)dst = TSDB_DATA_TYPE_JSON;
     setNull(dst + CHAR_BYTES, TSDB_DATA_TYPE_JSON, 0);
     return dst;
   }
@@ -5412,7 +5406,7 @@ void* getJsonTagValueElment(STable* data, char* key, int32_t keyLen, char* dst,
 void getJsonTagValueAll(void* data, void* dst, int16_t bytes) {
   char* json = parseTagDatatoJson(data);
   char* tagData = dst + CHAR_BYTES;
-  *(char*)dst = TSDB_DATA_TYPE_NCHAR;
+  *(char*)dst = TSDB_DATA_TYPE_JSON;
   if(json == NULL){
     setNull(tagData, TSDB_DATA_TYPE_JSON, 0);
     return;
diff --git a/src/query/src/queryMain.c b/src/query/src/queryMain.c
index dae0a237489ba3b0c5c642cfe0a796122bf5747a..e8d147d5398121d82c5f7860901eb78567cca087 100644
--- a/src/query/src/queryMain.c
+++ b/src/query/src/queryMain.c
@@ -83,12 +83,12 @@ static void* setJsonTagSchema(void* tsdb, int16_t numOfOutput, SExprInfo *pExprs
     SSqlExpr* sqlExpr = &pExprs[i].base;
     if (sqlExpr->colType == TSDB_DATA_TYPE_JSON && sqlExpr->numOfParams > 0){
       TagJsonSSchema* schema = (TagJsonSSchema*)(tmp);
-      schema->type = TSDB_DATA_TYPE_NULL;
+      schema->type = TSDB_DATA_TYPE_JSON;
       tstrncpy(schema->name, sqlExpr->aliasName, TSDB_MAX_JSON_KEY_LEN);
       for (int j = 0; j < taosArrayGetSize(pTableIdList); ++j) {
         STableIdInfo *id = taosArrayGet(pTableIdList, j);
         uint8_t type = getTagJsonType(tsdb, id->uid, sqlExpr->param[0].pz, sqlExpr->param[0].nLen);
-        if(type != TSDB_DATA_TYPE_NULL) {
+        if(type != TSDB_DATA_TYPE_JSON) {
           schema->type = type;
           break;
         }
diff --git a/src/tsdb/src/tsdbRead.c b/src/tsdb/src/tsdbRead.c
index e982530f90cc206c357d1e926785e78d3ddac916..37dd692a15df02710660821145ea3d5a576dd582 100644
--- a/src/tsdb/src/tsdbRead.c
+++ b/src/tsdb/src/tsdbRead.c
@@ -4118,7 +4118,7 @@ uint8_t getTagJsonType(STsdbRepo* tsdb, uint64_t uid, char* key, int32_t len){
   if(result){
     return *(char*)result;
   }else{
-    return TSDB_DATA_TYPE_NULL;
+    return TSDB_DATA_TYPE_JSON;
   }
 }