support select 1

src/client/src/tscSQLParser.c

@@ -5908,12 +5908,16 @@ int32_t doLocalQueryProcess(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, SQuerySQL* pQ
   if (pExprList->nExpr != 1) {
     return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg1);
   }
-
+  bool server_status = false;
   tSQLExpr* pExpr = pExprList->a[0].pNode;
   if (pExpr->operand.z == NULL) {
+    //handle 'select 1'
+    if (pExpr->token.n == 1 && 0 == strncasecmp(pExpr->token.z, "1", 1)) {
+      server_status = true; 
+    } else {
       return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg2);
     } 
-
+  } 
   // TODO redefine the function
    SDNodeDynConfOption functionsInfo[5] = {{"database()", 10},
                                             {"server_version()", 16},
@@ -5922,6 +5926,9 @@ int32_t doLocalQueryProcess(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, SQuerySQL* pQ
                                             {"current_user()", 14}};
 
   int32_t index = -1;
+  if (server_status == true) {
+    index = 2;
+  } else {
     for (int32_t i = 0; i < tListLen(functionsInfo); ++i) {
       if (strncasecmp(functionsInfo[i].name, pExpr->operand.z, functionsInfo[i].len) == 0 &&
           functionsInfo[i].len == pExpr->operand.n) {
@@ -5929,6 +5936,7 @@ int32_t doLocalQueryProcess(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, SQuerySQL* pQ
         break;
       }
     }
+  }
 
   switch (index) {
     case 0: