fix: select null error

source/libs/command/src/command.c

@@ -270,10 +270,10 @@ static void setCreateDBResultIntoDataBlock(SSDataBlock* pBlock, char* dbFName, S
       "CREATE DATABASE `%s` BUFFER %d CACHESIZE %d CACHEMODEL '%s' COMP %d DURATION %dm "
       "WAL_FSYNC_PERIOD %d MAXROWS %d MINROWS %d KEEP %dm,%dm,%dm PAGES %d PAGESIZE %d PRECISION '%s' REPLICA %d "
       "STRICT '%s' WAL_LEVEL %d VGROUPS %d SINGLE_STABLE %d",
-      dbFName, pCfg->buffer, pCfg->cacheSize, cacheModelStr(pCfg->cacheLast), pCfg->compression, pCfg->daysPerFile, pCfg->walFsyncPeriod,
-      pCfg->maxRows, pCfg->minRows, pCfg->daysToKeep0, pCfg->daysToKeep1, pCfg->daysToKeep2, pCfg->pages,
-      pCfg->pageSize, prec, pCfg->replications, strictStr(pCfg->strict), pCfg->walLevel, pCfg->numOfVgroups,
-      1 == pCfg->numOfStables);
+      dbFName, pCfg->buffer, pCfg->cacheSize, cacheModelStr(pCfg->cacheLast), pCfg->compression, pCfg->daysPerFile,
+      pCfg->walFsyncPeriod, pCfg->maxRows, pCfg->minRows, pCfg->daysToKeep0, pCfg->daysToKeep1, pCfg->daysToKeep2,
+      pCfg->pages, pCfg->pageSize, prec, pCfg->replications, strictStr(pCfg->strict), pCfg->walLevel,
+      pCfg->numOfVgroups, 1 == pCfg->numOfStables);
 
   if (retentions) {
     len += sprintf(buf2 + VARSTR_HEADER_SIZE + len, " RETENTIONS %s", retentions);
@@ -500,8 +500,8 @@ static int32_t setCreateTBResultIntoDataBlock(SSDataBlock* pBlock, SDbCfgInfo* p
     terrno = TSDB_CODE_TSC_OUT_OF_MEMORY;
     return terrno;
   }
-  
-  int32_t          len = 0;
+
+  int32_t len = 0;
 
   if (TSDB_SUPER_TABLE == pCfg->tableType) {
     len += sprintf(buf2 + VARSTR_HEADER_SIZE, "CREATE STABLE `%s` (", tbName);
@@ -533,7 +533,7 @@ static int32_t setCreateTBResultIntoDataBlock(SSDataBlock* pBlock, SDbCfgInfo* p
   colDataAppend(pCol2, 0, buf2, false);
 
   taosMemoryFree(buf2);
-  
+
   return TSDB_CODE_SUCCESS;
 }
 
@@ -691,9 +691,15 @@ static int32_t createSelectResultDataBlock(SNodeList* pProjects, SSDataBlock** p
 
   SNode* pProj = NULL;
   FOREACH(pProj, pProjects) {
+    SExprNode*      pExpr = (SExprNode*)pProj;
     SColumnInfoData infoData = {0};
-    infoData.info.type = ((SExprNode*)pProj)->resType.type;
-    infoData.info.bytes = ((SExprNode*)pProj)->resType.bytes;
+    if (TSDB_DATA_TYPE_NULL == pExpr->resType.type) {
+      infoData.info.type = TSDB_DATA_TYPE_VARCHAR;
+      infoData.info.bytes = 0;
+    } else {
+      infoData.info.type = pExpr->resType.type;
+      infoData.info.bytes = pExpr->resType.bytes;
+    }
     blockDataAppendColInfo(pBlock, &infoData);
   }
   *pOutput = pBlock;

source/libs/parser/inc/sql.y

@@ -654,7 +654,7 @@ cgroup_name(A) ::= NK_ID(B).
 
 /************************************************ expression **********************************************************/
 expr_or_subquery(A) ::= expression(B).                                            { A = B; }
-expr_or_subquery(A) ::= subquery(B).                                              { A = B; }
+//expr_or_subquery(A) ::= subquery(B).                                              { A = createTempTableNode(pCxt, releaseRawExprNode(pCxt, B), NULL); }
 
 expression(A) ::= literal(B).                                                     { A = B; }
 expression(A) ::= pseudo_column(B).                                               { A = B; }

source/libs/parser/src/parCalcConst.c

@@ -372,14 +372,42 @@ static bool isEmptyResultQuery(SNode* pStmt) {
   return isEmptyResult;
 }
 
+static void resetProjectNullTypeImpl(SNodeList* pProjects) {
+  SNode* pProj = NULL;
+  FOREACH(pProj, pProjects) {
+    SExprNode* pExpr = (SExprNode*)pProj;
+    if (TSDB_DATA_TYPE_NULL == pExpr->resType.type) {
+      pExpr->resType.type = TSDB_DATA_TYPE_VARCHAR;
+      pExpr->resType.bytes = 0;
+    }
+  }
+}
+
+static void resetProjectNullType(SNode* pStmt) {
+  switch (nodeType(pStmt)) {
+    case QUERY_NODE_SELECT_STMT:
+      resetProjectNullTypeImpl(((SSelectStmt*)pStmt)->pProjectionList);
+      break;
+    case QUERY_NODE_SET_OPERATOR: {
+      resetProjectNullTypeImpl(((SSetOperator*)pStmt)->pProjectionList);
+      break;
+    }
+    default:
+      break;
+  }
+}
+
 int32_t calculateConstant(SParseContext* pParseCxt, SQuery* pQuery) {
   SCalcConstContext cxt = {.pParseCxt = pParseCxt,
                            .msgBuf.buf = pParseCxt->pMsg,
                            .msgBuf.len = pParseCxt->msgLen,
                            .code = TSDB_CODE_SUCCESS};
   int32_t           code = calcConstQuery(&cxt, pQuery->pRoot, false);
-  if (TSDB_CODE_SUCCESS == code && isEmptyResultQuery(pQuery->pRoot)) {
-    pQuery->execMode = QUERY_EXEC_MODE_EMPTY_RESULT;
+  if (TSDB_CODE_SUCCESS == code) {
+    resetProjectNullType(pQuery->pRoot);
+    if (isEmptyResultQuery(pQuery->pRoot)) {
+      pQuery->execMode = QUERY_EXEC_MODE_EMPTY_RESULT;
+    }
   }
   return code;
 }