Merge pull request #3446 from taosdata/feature/TD-1370

[TD-1370]<enhance>: support function count(1)

src/client/src/tscSQLParser.c

@@ -1597,13 +1597,14 @@ int32_t addExprAndResultField(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, int32_t col
       SColumnIndex index = COLUMN_INDEX_INITIALIZER;
 
       if (pItem->pNode->pParam != NULL) {
-        SStrToken* pToken = &pItem->pNode->pParam->a[0].pNode->colInfo;
-        if (pToken->z == NULL || pToken->n == 0) {
+        tSQLExprItem* pParamElem = &pItem->pNode->pParam->a[0];
+        SStrToken* pToken = &pParamElem->pNode->colInfo;
+        short sqlOptr = pParamElem->pNode->nSQLOptr;
+        if ((pToken->z == NULL || pToken->n == 0) 
+            && (TK_INTEGER != sqlOptr)) /*select count(1) from table*/ {
           return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg3);
         } 
-
-        tSQLExprItem* pParamElem = &pItem->pNode->pParam->a[0];
-        if (pParamElem->pNode->nSQLOptr == TK_ALL) {
+        if (sqlOptr == TK_ALL) {
           // select table.*
           // check if the table name is valid or not
           SStrToken tmpToken = pParamElem->pNode->colInfo;
@@ -1615,6 +1616,21 @@ int32_t addExprAndResultField(SSqlCmd* pCmd, SQueryInfo* pQueryInfo, int32_t col
           index = (SColumnIndex){0, PRIMARYKEY_TIMESTAMP_COL_INDEX};
           int32_t size = tDataTypeDesc[TSDB_DATA_TYPE_BIGINT].nSize;
           pExpr = tscSqlExprAppend(pQueryInfo, functionID, &index, TSDB_DATA_TYPE_BIGINT, size, size, false);
+        } else if (sqlOptr == TK_INTEGER) { // select count(1) from table1
+          char buf[8] = {0};  
+          int64_t val = -1;
+          tVariant* pVariant = &pParamElem->pNode->val;
+          if (pVariant->nType == TSDB_DATA_TYPE_BIGINT) {
+            tVariantDump(pVariant, buf, TSDB_DATA_TYPE_BIGINT, true);
+            val = GET_INT64_VAL(buf); 
+          }
+          if (val == 1) {
+            index = (SColumnIndex){0, PRIMARYKEY_TIMESTAMP_COL_INDEX};
+            int32_t size = tDataTypeDesc[TSDB_DATA_TYPE_BIGINT].nSize;
+            pExpr = tscSqlExprAppend(pQueryInfo, functionID, &index, TSDB_DATA_TYPE_BIGINT, size, size, false);
+          } else {
+            return invalidSqlErrMsg(tscGetErrorMsgPayload(pCmd), msg3);
+          }
         } else {
           // count the number of meters created according to the super table
           if (getColumnIndexByName(pCmd, pToken, pQueryInfo, &index) != TSDB_CODE_SUCCESS) {

tests/script/general/compute/count.sim

@@ -52,6 +52,12 @@ if $data00 != $rowNum then
   return -1
 endi
 
+sql select count(1) from $tb
+print ===> select count(1) from $tb => $data00
+if $data00 != $rowNum then 
+  return -1
+endi
+
 sql select count(tbcol) from $tb
 print ===> $data00
 if $data00 != $rowNum then 
@@ -102,13 +108,20 @@ if $data00 != $totalNum then
   return -1
 endi
 
+print =============== step8
+sql select count(1) from $mt
+print ===> $data00
+if $data00 != $totalNum then 
+  return -1
+endi
+
 sql select count(tbcol) from $mt
 print ===> $data00
 if $data00 != $totalNum then 
   return -1
 endi
 
-print =============== step8
+print =============== step10
 sql select count(tbcol) as c from $mt where ts < now + 4m
 print ===> $data00
 if $data00 != 50 then