diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index f244e01a09869d0ffbf440ad531222d88444944b..5b239d3bfb2d36264bb923935eabe2229186125c 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -4663,6 +4663,9 @@ int32_t getQueryCondExpr(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, tSqlExpr** pExpr
     }
 
     *type = rightType;
+
+    *tbIdx = (leftTbIdx == rightTbIdx) ? leftTbIdx : -1;
+    
     return TSDB_CODE_SUCCESS;
   }