diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index c0627f4c31..9a3b36895d 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -6020,7 +6020,7 @@ int32_t setAlterTableInfo(SSqlObj* pSql, struct SSqlInfo* pInfo) {
     int16_t i;
     uint32_t nLen = 0;
     for (i = 0; i < numOfColumns; ++i) {
-      nLen += pSchema[i].colId != columnIndex.columnIndex ? pSchema[i].bytes : pItem->bytes;
+      nLen += (i != columnIndex.columnIndex) ? pSchema[i].bytes : pItem->bytes;
     }
     if (nLen >= TSDB_MAX_BYTES_PER_ROW) {
       return invalidOperationMsg(pMsg, msg24);
@@ -6066,14 +6066,14 @@ int32_t setAlterTableInfo(SSqlObj* pSql, struct SSqlInfo* pInfo) {
       return invalidOperationMsg(pMsg, msg22);
     }
 
-    SSchema* pSchema = (SSchema*) pTableMetaInfo->pTableMeta->schema;
-    int16_t numOfColumns = pTableMetaInfo->pTableMeta->tableInfo.numOfColumns;
+    SSchema* pSchema = tscGetTableTagSchema(pTableMetaInfo->pTableMeta);
+    int16_t numOfTags = tscGetNumOfTags(pTableMetaInfo->pTableMeta);
     int16_t i;
     uint32_t nLen = 0;
-    for (i = 0; i < numOfColumns; ++i) {
-      nLen += pSchema[i].colId != columnIndex.columnIndex ? pSchema[i].bytes : pItem->bytes;
+    for (i = 0; i < numOfTags; ++i) {
+      nLen += (i != columnIndex.columnIndex) ? pSchema[i].bytes : pItem->bytes;
     }
-    if (nLen >= TSDB_MAX_BYTES_PER_ROW) {
+    if (nLen >= TSDB_MAX_TAGS_LEN) {
       return invalidOperationMsg(pMsg, msg24);
     }
 
diff --git a/src/query/src/qSqlParser.c b/src/query/src/qSqlParser.c
index 874ec7b692..eb920b3e17 100644
--- a/src/query/src/qSqlParser.c
+++ b/src/query/src/qSqlParser.c
@@ -712,9 +712,8 @@ void tSetColumnType(TAOS_FIELD *pField, SStrToken *type) {
     } else {
       int32_t bytes = -(int32_t)(type->type);
       if (bytes > (TSDB_MAX_NCHAR_LEN - VARSTR_HEADER_SIZE) / TSDB_NCHAR_SIZE) {
-        // we have to postpone reporting the error because it cannot be done here
-        // as pField->bytes is int16_t, use 'TSDB_MAX_NCHAR_LEN + 1' to avoid overflow
-        bytes = TSDB_MAX_NCHAR_LEN + 1;
+        // overflowed. set bytes to -1 so that error can be reported
+        bytes = -1;
       } else {
         bytes = bytes * TSDB_NCHAR_SIZE + VARSTR_HEADER_SIZE;
       }
@@ -727,8 +726,8 @@ void tSetColumnType(TAOS_FIELD *pField, SStrToken *type) {
     } else {
       int32_t bytes = -(int32_t)(type->type);
       if (bytes > TSDB_MAX_BINARY_LEN - VARSTR_HEADER_SIZE) {
-        // refer comment for NCHAR above
-        bytes = TSDB_MAX_BINARY_LEN + 1;
+        // overflowed. set bytes to -1 so that error can be reported
+        bytes = -1;
       } else {
         bytes += VARSTR_HEADER_SIZE;
       }