diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index d78eb65f2e..ec1421c2c9 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -7822,17 +7822,29 @@ int32_t validateSqlNode(SSqlObj* pSql, SSqlNode* pSqlNode, SQueryInfo* pQueryInf
         return code;
       }
     }
+    
+    int32_t timeWindowQuery =
+        (TPARSER_HAS_TOKEN(pSqlNode->interval.interval) || TPARSER_HAS_TOKEN(pSqlNode->sessionVal.gap));
 
-    if (validateSelectNodeList(pCmd, pQueryInfo, pSqlNode->pSelNodeList, false, false, false) != TSDB_CODE_SUCCESS) {
+    if (validateSelectNodeList(pCmd, pQueryInfo, pSqlNode->pSelNodeList, false, false, timeWindowQuery) != TSDB_CODE_SUCCESS) {
+      return TSDB_CODE_TSC_INVALID_OPERATION;
+    }
+    // parse the window_state
+    if (validateStateWindowNode(pCmd, pQueryInfo, pSqlNode, false) != TSDB_CODE_SUCCESS) {
       return TSDB_CODE_TSC_INVALID_OPERATION;
     }
-
     // todo NOT support yet
     for(int32_t i = 0; i < tscNumOfExprs(pQueryInfo); ++i) {
       SExprInfo* pExpr = tscExprGet(pQueryInfo, i);
       int32_t f = pExpr->base.functionId;
       if (f == TSDB_FUNC_STDDEV || f == TSDB_FUNC_PERCT) {
         return invalidOperationMsg(tscGetErrorMsgPayload(pCmd), msg6);
+      } 
+
+      if ((timeWindowQuery || pQueryInfo->stateWindow) && f == TSDB_FUNC_LAST) {
+        pExpr->base.numOfParams = 1;
+        pExpr->base.param[0].i64 = TSDB_ORDER_ASC;
+        pExpr->base.param[0].nType = TSDB_DATA_TYPE_INT;
       }
     }
 
@@ -7863,7 +7875,10 @@ int32_t validateSqlNode(SSqlObj* pSql, SSqlNode* pSqlNode, SQueryInfo* pQueryInf
     if (validateIntervalNode(pSql, pQueryInfo, pSqlNode) != TSDB_CODE_SUCCESS) {
       return TSDB_CODE_TSC_INVALID_OPERATION;
     } else {
-      if (isTimeWindowQuery(pQueryInfo) || pQueryInfo->sessionWindow.gap > 0) {
+      if (validateSessionNode(pCmd, pQueryInfo, pSqlNode) != TSDB_CODE_SUCCESS) {
+        return TSDB_CODE_TSC_INVALID_OPERATION;
+      }
+      if (isTimeWindowQuery(pQueryInfo)) {
         // check if the first column of the nest query result is timestamp column
         SColumn* pCol = taosArrayGetP(pQueryInfo->colList, 0);
         if (pCol->info.type != TSDB_DATA_TYPE_TIMESTAMP) {
@@ -7972,8 +7987,7 @@ int32_t validateSqlNode(SSqlObj* pSql, SSqlNode* pSqlNode, SQueryInfo* pQueryInf
       return TSDB_CODE_TSC_INVALID_OPERATION;
     }
 
-    if ((isTimeWindowQuery(pQueryInfo) || pQueryInfo->sessionWindow.gap > 0) &&
-        (validateFunctionsInIntervalOrGroupbyQuery(pCmd, pQueryInfo) != TSDB_CODE_SUCCESS)) {
+    if (isTimeWindowQuery(pQueryInfo) && (validateFunctionsInIntervalOrGroupbyQuery(pCmd, pQueryInfo) != TSDB_CODE_SUCCESS)) {
       return TSDB_CODE_TSC_INVALID_OPERATION;
     }
 
diff --git a/src/query/src/qExecutor.c b/src/query/src/qExecutor.c
index 75c0b0d22a..69b17504d3 100644
--- a/src/query/src/qExecutor.c
+++ b/src/query/src/qExecutor.c
@@ -1751,7 +1751,10 @@ static int32_t setupQueryRuntimeEnv(SQueryRuntimeEnv *pRuntimeEnv, int32_t numOf
       case OP_SessionWindow: {
         pRuntimeEnv->proot =
             createSWindowOperatorInfo(pRuntimeEnv, pRuntimeEnv->proot, pQueryAttr->pExpr1, pQueryAttr->numOfOutput);
-        setTableScanFilterOperatorInfo(pRuntimeEnv->proot->upstream[0]->info, pRuntimeEnv->proot);
+        int32_t opType = pRuntimeEnv->proot->upstream[0]->operatorType;
+        if (opType != OP_DummyInput) {
+          setTableScanFilterOperatorInfo(pRuntimeEnv->proot->upstream[0]->info, pRuntimeEnv->proot);
+        }
         break;
       }
       case OP_MultiTableAggregate: {
@@ -1787,7 +1790,10 @@ static int32_t setupQueryRuntimeEnv(SQueryRuntimeEnv *pRuntimeEnv, int32_t numOf
       }
       case OP_StateWindow: {
         pRuntimeEnv->proot = createStatewindowOperatorInfo(pRuntimeEnv, pRuntimeEnv->proot, pQueryAttr->pExpr1, pQueryAttr->numOfOutput); 
-        setTableScanFilterOperatorInfo(pRuntimeEnv->proot->upstream[0]->info, pRuntimeEnv->proot);
+        int32_t opType = pRuntimeEnv->proot->upstream[0]->operatorType;
+        if (opType != OP_DummyInput) {
+          setTableScanFilterOperatorInfo(pRuntimeEnv->proot->upstream[0]->info, pRuntimeEnv->proot);
+        }
         break;
       }
 
diff --git a/tests/pytest/query/querySession.py b/tests/pytest/query/querySession.py
index 620f755bcb..216ff68b71 100644
--- a/tests/pytest/query/querySession.py
+++ b/tests/pytest/query/querySession.py
@@ -51,38 +51,73 @@ class TDTestCase:
         tdSql.checkRows(15)
         tdSql.checkData(0, 1, 2)
 
+        # session(ts,5a) main query
+        tdSql.query("select count(*) from (select * from dev_001) session(ts,5a)")
+        tdSql.checkRows(15)
+        tdSql.checkData(0, 1, 2)
+
 
         # session(ts,1s)
         tdSql.query("select count(*) from dev_001 session(ts,1s)")
         tdSql.checkRows(12)
         tdSql.checkData(0, 1, 5)
 
+        # session(ts,1s) main query
+        tdSql.query("select count(*) from (select * from dev_001) session(ts,1s)")
+        tdSql.checkRows(12)
+        tdSql.checkData(0, 1, 5)
+
         tdSql.query("select count(*) from dev_001 session(ts,1000a)")
         tdSql.checkRows(12)
         tdSql.checkData(0, 1, 5)
 
+        tdSql.query("select count(*) from  (select * from dev_001) session(ts,1000a)")
+        tdSql.checkRows(12)
+        tdSql.checkData(0, 1, 5)
+
         # session(ts,1m)
         tdSql.query("select count(*) from dev_001 session(ts,1m)")
         tdSql.checkRows(9)
         tdSql.checkData(0, 1, 8)
 
+        # session(ts,1m)
+        tdSql.query("select count(*) from (select * from dev_001) session(ts,1m)")
+        tdSql.checkRows(9)
+        tdSql.checkData(0, 1, 8)
+
         # session(ts,1h)
         tdSql.query("select count(*) from dev_001 session(ts,1h)")
         tdSql.checkRows(6)
         tdSql.checkData(0, 1, 11)
 
+        # session(ts,1h)
+        tdSql.query("select count(*) from (select * from dev_001) session(ts,1h)")
+        tdSql.checkRows(6)
+        tdSql.checkData(0, 1, 11)
+
         # session(ts,1d)
         tdSql.query("select count(*) from dev_001 session(ts,1d)")
         tdSql.checkRows(4)
         tdSql.checkData(0, 1, 13)
 
+        # session(ts,1d)
+        tdSql.query("select count(*) from (select * from dev_001) session(ts,1d)")
+        tdSql.checkRows(4)
+        tdSql.checkData(0, 1, 13)
+
         # session(ts,1w)
         tdSql.query("select count(*) from dev_001 session(ts,1w)")
         tdSql.checkRows(2)
         tdSql.checkData(0, 1, 15)
 
+        # session(ts,1w)
+        tdSql.query("select count(*) from (select * from dev_001) session(ts,1w)")
+        tdSql.checkRows(2)
+        tdSql.checkData(0, 1, 15)
+
         # session with where 
         tdSql.query("select count(*),first(tagtype),last(tagtype),avg(tagtype),sum(tagtype),min(tagtype),max(tagtype),leastsquares(tagtype, 1, 1),spread(tagtype),stddev(tagtype),percentile(tagtype,0)  from dev_001 where ts <'2020-05-20 0:0:0' session(ts,1d)")
+
         tdSql.checkRows(2)
         tdSql.checkData(0, 1, 13)
         tdSql.checkData(0, 2, 1)
@@ -97,6 +132,20 @@ class TDTestCase:
         tdSql.checkData(0, 11, 1)
         tdSql.checkData(1, 11, 14)
 
+        # session with where main
+
+        tdSql.query("select count(*),first(tagtype),last(tagtype),avg(tagtype),sum(tagtype),min(tagtype),max(tagtype),leastsquares(tagtype, 1, 1) from (select * from dev_001 where ts <'2020-05-20 0:0:0') session(ts,1d)")
+
+        tdSql.checkRows(2)
+        tdSql.checkData(0, 1, 13)
+        tdSql.checkData(0, 2, 1)
+        tdSql.checkData(0, 3, 13)
+        tdSql.checkData(0, 4, 7)
+        tdSql.checkData(0, 5, 91)
+        tdSql.checkData(0, 6, 1)
+        tdSql.checkData(0, 7, 13)
+        tdSql.checkData(0, 8, '{slop:1.000000, intercept:0.000000}')
+
         # tdsql err
         tdSql.error("select * from dev_001 session(ts,1w)")
         tdSql.error("select count(*) from st session(ts,1w)")