官方说明

https://docwiki.embarcadero.com/RADStudio/Sydney/en/Querying_Metadata_(FireDAC)

https://docwiki.embarcadero.com/RADStudio/Sydney/en/Working_with_Metadata_(FireDAC)

https://docwiki.embarcadero.com/RADStudio/Sydney/en/Metadata_Structure_(FireDAC)#Table_Field_List_.28mkTableFields.29_and_Table_Type_Field_List_.28mkTableTypeFields.29

  FDMetaInfoQuery1.MetaInfoKind := mkTableFields;
  FDMetaInfoQuery1.ObjectName := 'aaa';  //表名
  FDMetaInfoQuery1.Open;
  var i:integer;
 for I := 0 to FDMetaInfoQuery1.FieldCount -1 do
    dbgrid2.Columns[i].Width:=50;