diff --git a/source/libs/function/src/builtins.c b/source/libs/function/src/builtins.c
index 99a247b45e..541346b330 100644
--- a/source/libs/function/src/builtins.c
+++ b/source/libs/function/src/builtins.c
@@ -530,10 +530,32 @@ int32_t stubCheckAndGetResultType(SFunctionNode* pFunc) {
     case FUNCTION_TYPE_CONCAT:
     case FUNCTION_TYPE_CONCAT_WS: {
       int32_t paraType, paraBytes = 0;
+      bool typeSet = false;
       for (int32_t i = 0; i < pFunc->pParameterList->length; ++i) {
         SColumnNode* pParam = nodesListGetNode(pFunc->pParameterList, i);
-        paraBytes += pParam->node.resType.bytes;
-        paraType = pParam->node.resType.type;
+        if (pParam->node.type == QUERY_NODE_COLUMN) {
+          if (typeSet == false) {
+            paraType = pParam->node.resType.type;
+            typeSet = true;
+          } else {
+            //columns have to be the same type
+            if (paraType != pParam->node.resType.type) {
+              return TSDB_CODE_FAILED;
+            }
+          }
+          paraBytes += pParam->node.resType.bytes;
+        }
+      }
+
+      for (int32_t i = 0; i < pFunc->pParameterList->length; ++i) {
+        SColumnNode* pParam = nodesListGetNode(pFunc->pParameterList, i);
+        if (pParam->node.type == QUERY_NODE_VALUE) {
+          if (paraType == TSDB_DATA_TYPE_NCHAR) {
+            paraBytes += pParam->node.resType.bytes * TSDB_NCHAR_SIZE;
+          } else {
+            paraBytes += pParam->node.resType.bytes;
+          }
+        }
       }
       pFunc->node.resType = (SDataType) { .bytes = paraBytes, .type = paraType };
       break;
diff --git a/source/libs/scalar/src/sclfunc.c b/source/libs/scalar/src/sclfunc.c
index c02729a084..e25fe4b41a 100644
--- a/source/libs/scalar/src/sclfunc.c
+++ b/source/libs/scalar/src/sclfunc.c
@@ -12,7 +12,7 @@ typedef void (*_trim_fn)(char *, char*, int32_t, int32_t);
 typedef int16_t (*_len_fn)(char *, int32_t);
 
 /** Math functions **/
-double tlog(double v, double base) {
+static double tlog(double v, double base) {
   return log(v) / log(base);
 }
 
@@ -113,7 +113,7 @@ int32_t absFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutpu
   return TSDB_CODE_SUCCESS;
 }
 
-int32_t doScalarFunctionUnique(SScalarParam *pInput, int32_t inputNum, SScalarParam* pOutput, _double_fn valFn) {
+static int32_t doScalarFunctionUnique(SScalarParam *pInput, int32_t inputNum, SScalarParam* pOutput, _double_fn valFn) {
   int32_t type = GET_PARAM_TYPE(pInput);
   if (inputNum != 1 || !IS_NUMERIC_TYPE(type)) {
     return TSDB_CODE_FAILED;
@@ -138,7 +138,7 @@ int32_t doScalarFunctionUnique(SScalarParam *pInput, int32_t inputNum, SScalarPa
   return TSDB_CODE_SUCCESS;
 }
 
-int32_t doScalarFunctionUnique2(SScalarParam *pInput, int32_t inputNum, SScalarParam* pOutput, _double_fn_2 valFn) {
+static int32_t doScalarFunctionUnique2(SScalarParam *pInput, int32_t inputNum, SScalarParam* pOutput, _double_fn_2 valFn) {
   if (inputNum != 2 || !IS_NUMERIC_TYPE(GET_PARAM_TYPE(&pInput[0])) || !IS_NUMERIC_TYPE(GET_PARAM_TYPE(&pInput[1]))) {
     return TSDB_CODE_FAILED;
   }
@@ -167,7 +167,7 @@ int32_t doScalarFunctionUnique2(SScalarParam *pInput, int32_t inputNum, SScalarP
   return TSDB_CODE_SUCCESS;
 }
 
-int32_t doScalarFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam* pOutput, _float_fn f1, _double_fn d1) {
+static int32_t doScalarFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam* pOutput, _float_fn f1, _double_fn d1) {
   int32_t type = GET_PARAM_TYPE(pInput);
   if (inputNum != 1 || !IS_NUMERIC_TYPE(type)) {
     return TSDB_CODE_FAILED;
@@ -215,11 +215,11 @@ int32_t doScalarFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam* p
 }
 
 /** String functions **/
-int16_t tlength(char *input, int32_t type) {
+static int16_t tlength(char *input, int32_t type) {
   return varDataLen(input);
 }
 
-int16_t tcharlength(char *input, int32_t type) {
+static int16_t tcharlength(char *input, int32_t type) {
   if (type == TSDB_DATA_TYPE_VARCHAR) {
     return varDataLen(input);
   } else { //NCHAR
@@ -227,7 +227,7 @@ int16_t tcharlength(char *input, int32_t type) {
   }
 }
 
-void tltrim(char *input, char *output, int32_t type, int32_t charLen) {
+static void tltrim(char *input, char *output, int32_t type, int32_t charLen) {
   int32_t numOfSpaces = 0;
   if (type == TSDB_DATA_TYPE_VARCHAR) {
     for (int32_t i = 0; i < charLen; ++i) {
@@ -257,7 +257,7 @@ void tltrim(char *input, char *output, int32_t type, int32_t charLen) {
   varDataSetLen(output, resLen);
 }
 
-void trtrim(char *input, char *output, int32_t type, int32_t charLen) {
+static void trtrim(char *input, char *output, int32_t type, int32_t charLen) {
   int32_t numOfSpaces = 0;
   if (type == TSDB_DATA_TYPE_VARCHAR) {
     for (int32_t i = charLen - 1; i >= 0; --i) {
@@ -286,7 +286,7 @@ void trtrim(char *input, char *output, int32_t type, int32_t charLen) {
   varDataSetLen(output, resLen);
 }
 
-int32_t doLengthFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutput, _len_fn lenFn) {
+static int32_t doLengthFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutput, _len_fn lenFn) {
   int32_t type = GET_PARAM_TYPE(pInput);
   if (inputNum != 1 || !IS_VAR_DATA_TYPE(type)) {
     return TSDB_CODE_FAILED;
@@ -312,12 +312,22 @@ int32_t doLengthFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *p
   return TSDB_CODE_SUCCESS;
 }
 
-static void setVarTypeOutputBuf(SColumnInfoData *pOutputData, int32_t len, int32_t type) {
-  pOutputData->pData = taosMemoryCalloc(len, sizeof(char));
-  pOutputData->info.type = type;
-  pOutputData->info.bytes = len;
-  pOutputData->varmeta.length = len;
-  pOutputData->varmeta.allocLen = len;
+static int32_t concatCopyHelper(const char *input, char *output, bool hasNcharCol, int32_t type, int16_t *dataLen) {
+  if (hasNcharCol && type == TSDB_DATA_TYPE_VARCHAR) {
+    TdUcs4 *newBuf = taosMemoryCalloc((varDataLen(input) + 1) * TSDB_NCHAR_SIZE, 1);
+    bool ret = taosMbsToUcs4(varDataVal(input), varDataLen(input), newBuf, (varDataLen(input) + 1) * TSDB_NCHAR_SIZE, NULL);
+    if (!ret) {
+      taosMemoryFree(newBuf);
+      return TSDB_CODE_FAILED;
+    }
+    memcpy(varDataVal(output) + *dataLen, newBuf, varDataLen(input) * TSDB_NCHAR_SIZE);
+    *dataLen += varDataLen(input) * TSDB_NCHAR_SIZE;
+    taosMemoryFree(newBuf);
+  } else {
+    memcpy(varDataVal(output) + *dataLen, varDataVal(input), varDataLen(input));
+    *dataLen += varDataLen(input);
+  }
+  return TSDB_CODE_SUCCESS;
 }
 
 int32_t concatFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutput) {
@@ -332,11 +342,15 @@ int32_t concatFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOu
 
   int32_t inputLen = 0;
   int32_t numOfRows = 0;
+  bool hasNcharCol = false;
   for (int32_t i = 0; i < inputNum; ++i) {
-    if (!IS_VAR_DATA_TYPE(GET_PARAM_TYPE(&pInput[i])) ||
-        GET_PARAM_TYPE(&pInput[i]) != GET_PARAM_TYPE(&pInput[0])) {
+    int32_t type = GET_PARAM_TYPE(&pInput[i]);
+    if (!IS_VAR_DATA_TYPE(type)) {
       return TSDB_CODE_FAILED;
     }
+    if (type == TSDB_DATA_TYPE_NCHAR) {
+      hasNcharCol = true;
+    }
     if (pInput[i].numOfRows > numOfRows) {
       numOfRows = pInput[i].numOfRows;
     }
@@ -344,8 +358,12 @@ int32_t concatFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOu
   for (int32_t i = 0; i < inputNum; ++i) {
     pInputData[i] = pInput[i].columnData;
     input[i] = pInputData[i]->pData;
+    int32_t factor = 1;
+    if (hasNcharCol && (GET_PARAM_TYPE(&pInput[i]) == TSDB_DATA_TYPE_VARCHAR)) {
+      factor = TSDB_NCHAR_SIZE;
+    }
     if (pInput[i].numOfRows == 1) {
-      inputLen += (pInputData[i]->varmeta.length - VARSTR_HEADER_SIZE) * numOfRows;
+      inputLen += (pInputData[i]->varmeta.length - VARSTR_HEADER_SIZE) * factor * numOfRows;
     } else {
       inputLen += pInputData[i]->varmeta.length - numOfRows * VARSTR_HEADER_SIZE;
     }
@@ -371,8 +389,10 @@ int32_t concatFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOu
 
     int16_t dataLen = 0;
     for (int32_t i = 0; i < inputNum; ++i) {
-      memcpy(varDataVal(output) + dataLen, varDataVal(input[i]), varDataLen(input[i]));
-      dataLen += varDataLen(input[i]);
+      int32_t ret = concatCopyHelper(input[i], output, hasNcharCol, GET_PARAM_TYPE(&pInput[i]), &dataLen);
+      if (ret != TSDB_CODE_SUCCESS) {
+        return ret;
+      }
       if (pInput[i].numOfRows != 1) {
         input[i] += varDataTLen(input[i]);
       }
@@ -390,6 +410,7 @@ int32_t concatFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOu
   return TSDB_CODE_SUCCESS;
 }
 
+
 int32_t concatWsFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutput) {
   if (inputNum < 3 || inputNum > 9) { // concat accpet 3-9 input strings including the separator
     return TSDB_CODE_FAILED;
@@ -402,27 +423,34 @@ int32_t concatWsFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *p
 
   int32_t inputLen = 0;
   int32_t numOfRows = 0;
+  bool hasNcharCol = false;
   for (int32_t i = 1; i < inputNum; ++i) {
-    if (!IS_VAR_DATA_TYPE(GET_PARAM_TYPE(&pInput[i])) ||
-        GET_PARAM_TYPE(&pInput[i]) != GET_PARAM_TYPE(&pInput[1])) {
+    int32_t type = GET_PARAM_TYPE(&pInput[i]);
+    if (!IS_VAR_DATA_TYPE(GET_PARAM_TYPE(&pInput[i]))) {
       return TSDB_CODE_FAILED;
     }
+    if (type == TSDB_DATA_TYPE_NCHAR) {
+      hasNcharCol = true;
+    }
     if (pInput[i].numOfRows > numOfRows) {
       numOfRows = pInput[i].numOfRows;
     }
   }
   for (int32_t i = 0; i < inputNum; ++i) {
     pInputData[i] = pInput[i].columnData;
+    input[i] = pInputData[i]->pData;
+    int32_t factor = 1;
+    if (hasNcharCol && (GET_PARAM_TYPE(&pInput[i]) == TSDB_DATA_TYPE_VARCHAR)) {
+      factor = TSDB_NCHAR_SIZE;
+    }
     if (i == 0) {
       // calculate required separator space
-      int32_t factor =  (GET_PARAM_TYPE(&pInput[1]) == TSDB_DATA_TYPE_NCHAR) ? TSDB_NCHAR_SIZE : 1;
       inputLen += (pInputData[0]->varmeta.length - VARSTR_HEADER_SIZE) * numOfRows * (inputNum - 2) * factor;
     } else if (pInput[i].numOfRows == 1) {
-      inputLen += (pInputData[i]->varmeta.length - VARSTR_HEADER_SIZE) * numOfRows;
+      inputLen += (pInputData[i]->varmeta.length - VARSTR_HEADER_SIZE) * numOfRows * factor;
     } else {
       inputLen += pInputData[i]->varmeta.length - numOfRows * VARSTR_HEADER_SIZE;
     }
-    input[i] = pInputData[i]->pData;
   }
 
   int32_t outputLen = inputLen + numOfRows * VARSTR_HEADER_SIZE;
@@ -441,8 +469,11 @@ int32_t concatWsFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *p
         continue;
       }
 
-      memcpy(varDataVal(output) + dataLen, varDataVal(input[i]), varDataLen(input[i]));
-      dataLen += varDataLen(input[i]);
+      int32_t ret = concatCopyHelper(input[i], output, hasNcharCol, GET_PARAM_TYPE(&pInput[i]), &dataLen);
+      if (ret != TSDB_CODE_SUCCESS) {
+        return ret;
+      }
+
       if (pInput[i].numOfRows != 1) {
         input[i] += varDataTLen(input[i]);
       }
@@ -450,8 +481,10 @@ int32_t concatWsFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *p
       if (i < inputNum - 1) {
         //insert the separator
         char *sep = pInputData[0]->pData;
-        memcpy(varDataVal(output) + dataLen, varDataVal(sep), varDataLen(sep));
-        dataLen += varDataLen(sep);
+        int32_t ret = concatCopyHelper(sep, output, hasNcharCol, GET_PARAM_TYPE(&pInput[0]), &dataLen);
+        if (ret != TSDB_CODE_SUCCESS) {
+          return ret;
+        }
       }
     }
     varDataSetLen(output, dataLen);
@@ -467,7 +500,7 @@ int32_t concatWsFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *p
   return TSDB_CODE_SUCCESS;
 }
 
-int32_t doCaseConvFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutput, _conv_fn convFn) {
+static int32_t doCaseConvFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutput, _conv_fn convFn) {
   int32_t type = GET_PARAM_TYPE(pInput);
   if (inputNum != 1 || !IS_VAR_DATA_TYPE(type)) {
     return TSDB_CODE_FAILED;
@@ -512,7 +545,7 @@ int32_t doCaseConvFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam
 }
 
 
-int32_t doTrimFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutput, _trim_fn trimFn) {
+static int32_t doTrimFunction(SScalarParam *pInput, int32_t inputNum, SScalarParam *pOutput, _trim_fn trimFn) {
   int32_t type = GET_PARAM_TYPE(pInput);
   if (inputNum != 1 || !IS_VAR_DATA_TYPE(type)) {
     return TSDB_CODE_FAILED;