func (c *ClientConn) newEmptyResultset(stmt *sqlparser.Select) *mysql.Resultset {
r := new(mysql.Resultset)
r.Fields = make([]*mysql.Field, len(stmt.SelectExprs))
for i, expr := range stmt.SelectExprs {
r.Fields[i] = &mysql.Field{}
switch e := expr.(type) {
case *sqlparser.StarExpr:
r.Fields[i].Name = []byte("*")
case *sqlparser.NonStarExpr:
if e.As != nil {
r.Fields[i].Name = e.As
r.Fields[i].OrgName = hack.Slice(nstring(e.Expr))
} else {
r.Fields[i].Name = hack.Slice(nstring(e.Expr))
}
default:
r.Fields[i].Name = hack.Slice(nstring(e))
}
}
r.Values = make([][]interface{}, 0)
r.RowDatas = make([]mysql.RowData, 0)
return r
}
func (c *ClientConn) limitSelectResult(r *mysql.Resultset, stmt *sqlparser.Select) error {
if stmt.Limit == nil {
return nil
}
var offset, count int64
var err error
if stmt.Limit.Offset == nil {
offset = 0
} else {
if o, ok := stmt.Limit.Offset.(sqlparser.NumVal); !ok {
return fmt.Errorf("invalid select limit %s", nstring(stmt.Limit))
} else {
if offset, err = strconv.ParseInt(hack.String([]byte(o)), 10, 64); err != nil {
return err
}
}
}
if o, ok := stmt.Limit.Rowcount.(sqlparser.NumVal); !ok {
return fmt.Errorf("invalid limit %s", nstring(stmt.Limit))
} else {
if count, err = strconv.ParseInt(hack.String([]byte(o)), 10, 64); err != nil {
return err
} else if count < 0 {
return fmt.Errorf("invalid limit %s", nstring(stmt.Limit))
}
}
if offset+count > int64(len(r.Values)) {
count = int64(len(r.Values)) - offset
}
r.Values = r.Values[offset : offset+count]
r.RowDatas = r.RowDatas[offset : offset+count]
return nil
}