Merge pull request #17448 from taosdata/fix/TD-19619

fix(query): mode function output behavior if there're multiple highest frequency of occurrence.

docs/en/12-taos-sql/10-function.md

@@ -945,7 +945,7 @@ MIN(expr)
 MODE(expr)
 ```
 
-**Description**:The value which has the highest frequency of occurrence. NULL is returned if there are multiple values which have highest frequency of occurrence.
+**Description**:The value which has the highest frequency of occurrence. One random value is returned if there are multiple values which have highest frequency of occurrence.
 
 **Return value type**: Same as the input data
 

docs/zh/12-taos-sql/10-function.md

@@ -946,7 +946,7 @@ MIN(expr)
 MODE(expr)
 ```
 
-**功能说明**：返回出现频率最高的值，若存在多个频率相同的最高值，输出NULL。
+**功能说明**：返回出现频率最高的值，若存在多个频率相同的最高值，则随机输出其中某个值。
 
 **返回数据类型**：与输入数据类型一致。
 

source/libs/function/src/builtinsimpl.c

@@ -5359,16 +5359,14 @@ int32_t modeFinalize(SqlFunctionCtx* pCtx, SSDataBlock* pBlock) {
   int32_t maxCount = 0;
   for (int32_t i = 0; i < pInfo->numOfPoints; ++i) {
     SModeItem* pItem = (SModeItem*)(pInfo->pItems + i * (sizeof(SModeItem) + pInfo->colBytes));
-    if (pItem->count > maxCount) {
+    if (pItem->count >= maxCount) {
       maxCount = pItem->count;
       resIndex = i;
-    } else if (pItem->count == maxCount) {
-      resIndex = -1;
     }
   }
 
   SModeItem* pResItem = (SModeItem*)(pInfo->pItems + resIndex * (sizeof(SModeItem) + pInfo->colBytes));
-  colDataAppend(pCol, currentRow, pResItem->data, (resIndex == -1) ? true : false);
+  colDataAppend(pCol, currentRow, pResItem->data, (maxCount == 0) ? true : false);
 
   return pResInfo->numOfRes;
 }