From 7f514df778ce4545eec6e317273c905a0b8cf935 Mon Sep 17 00:00:00 2001
From: Haojun Liao <hjliao@taosdata.com>
Date: Sat, 23 May 2020 11:40:52 +0800
Subject: [PATCH] [td-338]

---
 src/client/src/tscSQLParser.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index a134410bc4..d68290653a 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -5606,7 +5606,8 @@ int32_t doCheckForStream(SSqlObj* pSql, SSqlInfo* pInfo) {
   const char* msg3 = "fill only available for interval query";
   const char* msg4 = "fill option not supported in stream computing";
   const char* msg5 = "sql too long";  // todo ADD support
-
+  const char* msg6 = "from missing in subclause";
+  
   SSqlCmd*    pCmd = &pSql->cmd;
   SQueryInfo* pQueryInfo = tscGetQueryInfoDetail(pCmd, 0);
   assert(pQueryInfo->numOfTables == 1);
@@ -5621,10 +5622,13 @@ int32_t doCheckForStream(SSqlObj* pSql, SSqlInfo* pInfo) {
   if (tscValidateName(pzTableName) != TSDB_CODE_SUCCESS) {
     return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg1);
   }
-
+  
   tVariantList* pSrcMeterName = pInfo->pCreateTableInfo->pSelect->from;
-  tVariant*     pVar = &pSrcMeterName->a[0].pVar;
-
+  if (pSrcMeterName == NULL || pSrcMeterName->nExpr == 0) {
+    return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg6);
+  }
+  
+  tVariant* pVar = &pSrcMeterName->a[0].pVar;
   SSQLToken srcToken = {.z = pVar->pz, .n = pVar->nLen, .type = TK_STRING};
   if (tscValidateName(&srcToken) != TSDB_CODE_SUCCESS) {
     return invalidSqlErrMsg(pQueryInfo->msg, msg1);
-- 
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