// Set ResultField info according to values
// This is used for inferring calculated fields type/Flen/charset
// For example "select count(*) from t;" will return a ResultField with type TypeLonglong, charset binary and Flen 21.
func setResultFieldInfo(fields []*field.ResultField, values []interface{}) error {
if len(fields) != len(values) {
return errors.Errorf("Fields and Values length unmatch %d VS %d", len(fields), len(values))
}
for i, rf := range fields {
if mysql.IsUninitializedType(rf.Col.Tp) {
// 0 == TypeDecimal, Tp maybe uninitialized
rf.Col.Charset = charset.CharsetBin
rf.Col.Collate = charset.CharsetBin
c := values[i]
switch v := c.(type) {
case int8, int16, int, int32, int64:
rf.Col.Tp = mysql.TypeLonglong
case uint8, uint16, uint, uint32, uint64:
rf.Col.Tp = mysql.TypeLonglong
rf.Col.Flag |= mysql.UnsignedFlag
case float32, float64:
rf.Col.Tp = mysql.TypeFloat
case string:
rf.Col.Tp = mysql.TypeVarchar
rf.Col.Flen = len(v)
rf.Col.Charset = mysql.DefaultCharset
rf.Col.Collate = mysql.DefaultCollationName
case []byte:
rf.Col.Tp = mysql.TypeBlob
case mysql.Time:
rf.Col.Tp = v.Type
case mysql.Duration:
rf.Col.Tp = mysql.TypeDuration
case mysql.Decimal:
rf.Col.Tp = mysql.TypeDecimal
case nil:
rf.Col.Tp = mysql.TypeNull
default:
return errors.Errorf("Unknown type %T", c)
}
if rf.Col.Flen == 0 {
rf.Col.Flen = mysql.GetDefaultFieldLength(rf.Col.Tp)
}
// TODO: set flags
}
}
return nil
}
// Next implements plan.Plan Next interface.
func (r *SelectFieldsDefaultPlan) Next(ctx context.Context) (row *plan.Row, err error) {
if r.evalArgs == nil {
r.evalArgs = map[interface{}]interface{}{}
}
srcRow, err := r.Src.Next(ctx)
if err != nil || srcRow == nil {
return nil, errors.Trace(err)
}
r.evalArgs[expression.ExprEvalIdentReferFunc] = func(name string, scope int, index int) (interface{}, error) {
if scope == expression.IdentReferFromTable {
return srcRow.FromData[index], nil
}
return getIdentValueFromOuterQuery(ctx, name)
}
row = &plan.Row{
Data: make([]interface{}, len(r.Fields)),
// must save FromData info for inner sub query use.
FromData: srcRow.Data,
}
for i, fld := range r.Fields {
d, err := fld.Expr.Eval(ctx, r.evalArgs)
if err != nil {
return nil, errors.Trace(err)
}
di, ok := d.(*types.DataItem)
if ok {
if mysql.IsUninitializedType(r.ResultFields[i].Col.Tp) {
r.ResultFields[i].Col.FieldType = *di.Type
}
}
row.Data[i] = d
}
updateRowStack(ctx, row.Data, row.FromData)
return
}