Golang Result.Columns方法代碼示例

func (s server) execStmt(stmt parser.Statement, params parameters, planMaker *planner) (driver.Result, error) {
	var result driver.Result
	if planMaker.txn == nil {
		if _, ok := stmt.(*parser.BeginTransaction); ok {
			// Start a transaction here and not in planMaker to prevent begin
			// transaction from being called within an auto-transaction below.
			planMaker.txn = client.NewTxn(s.db)
			planMaker.txn.SetDebugName("sql", 0)
		}
	} else if planMaker.txn.Proto.Status == proto.ABORTED {
		switch stmt.(type) {
		case *parser.CommitTransaction, *parser.RollbackTransaction:
			// Reset to allow starting a new transaction.
			planMaker.txn = nil
			return result, nil
		default:
			return result, errTransactionAborted
		}
	}
	// Bind all the placeholder variables in the stmt to actual values.
	if err := parser.FillArgs(stmt, params); err != nil {
		return result, err
	}
	var plan planNode
	// If there is a pending transaction.
	if planMaker.txn != nil {
		// Run in transaction planMaker.txn
		var err error
		if plan, err = planMaker.makePlan(stmt); err != nil {
			return result, err
		}
	} else {
		// No transaction. Run the command as a retryable block in an
		// auto-transaction.
		if err := s.db.Txn(func(txn *client.Txn) error {
			planMaker.txn = txn
			var err error
			plan, err = planMaker.makePlan(stmt)
			planMaker.txn = nil
			return err
		}); err != nil {
			return result, err
		}
	}
	result.Columns = plan.Columns()
	for plan.Next() {
		values := plan.Values()
		row := driver.Result_Row{Values: make([]driver.Datum, 0, len(values))}
		for _, val := range values {
			if val == parser.DNull {
				row.Values = append(row.Values, driver.Datum{})
			} else {
				switch vt := val.(type) {
				case parser.DBool:
					row.Values = append(row.Values, driver.Datum{BoolVal: (*bool)(&vt)})
				case parser.DInt:
					row.Values = append(row.Values, driver.Datum{IntVal: (*int64)(&vt)})
				case parser.DFloat:
					row.Values = append(row.Values, driver.Datum{FloatVal: (*float64)(&vt)})
				case parser.DString:
					row.Values = append(row.Values, driver.Datum{StringVal: (*string)(&vt)})
				case parser.DDate:
					s := vt.String()
					row.Values = append(row.Values, driver.Datum{StringVal: &s})
				case parser.DTimestamp:
					s := vt.String()
					row.Values = append(row.Values, driver.Datum{StringVal: &s})
				case parser.DInterval:
					s := vt.String()
					row.Values = append(row.Values, driver.Datum{StringVal: &s})
				default:
					return result, util.Errorf("unsupported datum: %T", val)
				}
			}
		}
		result.Rows = append(result.Rows, row)
	}
	if err := plan.Err(); err != nil {
		return result, err
	}
	return result, nil
}

func (e Executor) execStmt(stmt parser.Statement, params parameters, planMaker *planner) (driver.Result, error) {
	var result driver.Result
	switch stmt.(type) {
	case *parser.BeginTransaction:
		if planMaker.txn != nil {
			return result, errTransactionInProgress
		}
		// Start a transaction here and not in planMaker to prevent begin
		// transaction from being called within an auto-transaction below.
		planMaker.txn = client.NewTxn(e.db)
		planMaker.txn.SetDebugName("sql", 0)
	case *parser.CommitTransaction, *parser.RollbackTransaction:
		if planMaker.txn != nil {
			if planMaker.txn.Proto.Status == proto.ABORTED {
				// Reset to allow starting a new transaction.
				planMaker.txn = nil
				return result, nil
			}
		} else {
			return result, errNoTransactionInProgress
		}
	case *parser.SetTransaction:
		if planMaker.txn == nil {
			return result, errNoTransactionInProgress
		}
	default:
		if planMaker.txn != nil && planMaker.txn.Proto.Status == proto.ABORTED {
			return result, errTransactionAborted
		}
	}

	// Bind all the placeholder variables in the stmt to actual values.
	if err := parser.FillArgs(stmt, params); err != nil {
		return result, err
	}

	// Create a function which both makes and executes the plan, populating
	// result.
	//
	// TODO(pmattis): Should this be a separate function? Perhaps we should move
	// some of the common code back out into execStmts and have execStmt contain
	// only the body of this closure.
	f := func() error {
		plan, err := planMaker.makePlan(stmt)
		if err != nil {
			return err
		}

		result.Columns = plan.Columns()
		for plan.Next() {
			values := plan.Values()
			row := driver.Result_Row{Values: make([]driver.Datum, 0, len(values))}
			for _, val := range values {
				if val == parser.DNull {
					row.Values = append(row.Values, driver.Datum{})
				} else {
					switch vt := val.(type) {
					case parser.DBool:
						row.Values = append(row.Values, driver.Datum{
							Payload: &driver.Datum_BoolVal{BoolVal: bool(vt)},
						})
					case parser.DInt:
						row.Values = append(row.Values, driver.Datum{
							Payload: &driver.Datum_IntVal{IntVal: int64(vt)},
						})
					case parser.DFloat:
						row.Values = append(row.Values, driver.Datum{
							Payload: &driver.Datum_FloatVal{FloatVal: float64(vt)},
						})
					case parser.DBytes:
						row.Values = append(row.Values, driver.Datum{
							Payload: &driver.Datum_BytesVal{BytesVal: []byte(vt)},
						})
					case parser.DString:
						row.Values = append(row.Values, driver.Datum{
							Payload: &driver.Datum_StringVal{StringVal: string(vt)},
						})
					case parser.DDate:
						row.Values = append(row.Values, driver.Datum{
							Payload: &driver.Datum_TimeVal{
								TimeVal: &driver.Datum_Timestamp{
									Sec:  vt.Unix(),
									Nsec: uint32(vt.Nanosecond()),
								},
							},
						})
					case parser.DTimestamp:
						row.Values = append(row.Values, driver.Datum{
							Payload: &driver.Datum_TimeVal{
								TimeVal: &driver.Datum_Timestamp{
									Sec:  vt.Unix(),
									Nsec: uint32(vt.Nanosecond()),
								},
							},
						})
					case parser.DInterval:
						row.Values = append(row.Values, driver.Datum{
							Payload: &driver.Datum_StringVal{StringVal: vt.String()},
						})
					default:
//.........這裏部分代碼省略.........