From 7a215a238f19c2f751e7331edbea8f872e4fb6ae Mon Sep 17 00:00:00 2001
From: Xiaoyu Wang <xiaoyuwang@taosdata.com>
Date: Sat, 21 May 2022 20:58:12 +0800
Subject: [PATCH] fix: some prblems of parser and planner

---
 include/util/taoserror.h               | 1 +
 source/libs/parser/src/parTranslater.c | 9 +++++++--
 source/libs/parser/src/parUtil.c       | 2 ++
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/util/taoserror.h b/include/util/taoserror.h
index e28618d940..1d95ca7ca3 100644
--- a/include/util/taoserror.h
+++ b/include/util/taoserror.h
@@ -637,6 +637,7 @@ int32_t* taosGetErrno();
 #define TSDB_CODE_PAR_COMMENT_TOO_LONG          TAOS_DEF_ERROR_CODE(0, 0x264E)
 #define TSDB_CODE_PAR_NOT_ALLOWED_FUNC          TAOS_DEF_ERROR_CODE(0, 0x264F)
 #define TSDB_CODE_PAR_NOT_ALLOWED_WIN_QUERY     TAOS_DEF_ERROR_CODE(0, 0x2650)
+#define TSDB_CODE_PAR_INVALID_DROP_COL          TAOS_DEF_ERROR_CODE(0, 0x2651)
 
 //planner
 #define TSDB_CODE_PLAN_INTERNAL_ERROR           TAOS_DEF_ERROR_CODE(0, 0x2700)
diff --git a/source/libs/parser/src/parTranslater.c b/source/libs/parser/src/parTranslater.c
index 8e18c267d6..99e1135599 100644
--- a/source/libs/parser/src/parTranslater.c
+++ b/source/libs/parser/src/parTranslater.c
@@ -4454,8 +4454,10 @@ static int32_t buildUpdateTagValReq(STranslateContext* pCxt, SAlterTableStmt* pS
 
   pReq->isNull = (TSDB_DATA_TYPE_NULL == pStmt->pVal->node.resType.type);
   pReq->nTagVal = pStmt->pVal->node.resType.bytes;
-  char* pVal = nodesGetValueFromNode(pStmt->pVal);
-  pReq->pTagVal = IS_VAR_DATA_TYPE(pStmt->pVal->node.resType.type) ? pVal + VARSTR_HEADER_SIZE : pVal;
+  if (TSDB_DATA_TYPE_NCHAR == pStmt->pVal->node.resType.type) {
+    pReq->nTagVal = pReq->nTagVal * TSDB_NCHAR_SIZE;
+  }
+  pReq->pTagVal = nodesGetValueFromNode(pStmt->pVal);
 
   return TSDB_CODE_SUCCESS;
 }
@@ -4479,6 +4481,9 @@ static int32_t buildAddColReq(STranslateContext* pCxt, SAlterTableStmt* pStmt, S
 
 static int32_t buildDropColReq(STranslateContext* pCxt, SAlterTableStmt* pStmt, STableMeta* pTableMeta,
                                SVAlterTbReq* pReq) {
+  if (2 == getNumOfColumns(pTableMeta)) {
+    return generateSyntaxErrMsg(&pCxt->msgBuf, TSDB_CODE_PAR_INVALID_DROP_COL);
+  }
   SSchema* pSchema = getColSchema(pTableMeta, pStmt->colName);
   if (NULL == pSchema) {
     return generateSyntaxErrMsg(&pCxt->msgBuf, TSDB_CODE_PAR_INVALID_COLUMN, pStmt->colName);
diff --git a/source/libs/parser/src/parUtil.c b/source/libs/parser/src/parUtil.c
index fe21915b1a..3df9c8abf7 100644
--- a/source/libs/parser/src/parUtil.c
+++ b/source/libs/parser/src/parUtil.c
@@ -169,6 +169,8 @@ static char* getSyntaxErrFormat(int32_t errCode) {
              "And, cannot be mixed with other non scalar functions or columns.";
     case TSDB_CODE_PAR_NOT_ALLOWED_WIN_QUERY:
       return "Window query not supported, since the result of subquery not include valid timestamp column";
+    case TSDB_CODE_PAR_INVALID_DROP_COL:
+      return "No columns can be dropped";
     case TSDB_CODE_OUT_OF_MEMORY:
       return "Out of memory";
     default: