>what's memo field? what's the usage of it? Thanks.
A memo field stores variable-length character data. With the Character type, if you reserve 50 bytes, every record will use 50 bytes, whether you use it or not. Also, you are limited to a maximum of 254 characters.
With memo, only 4 bytes is used in the main table (.DBF). If any data is used in a record, it is stored in a separate file (.FPT), where it uses only the amount of data required (see SET BLOCKSIZE). Also, you can have fairly large texts.
For binary data, you can use memo-binary, to avoid codepage translations. In version 9 of VFP, there is also a BLOB type (if I remember correctly), with a similar function.
Difference in opinions hath cost many millions of lives: for instance, whether flesh be bread, or bread be flesh; whether whistling be a vice or a virtue; whether it be better to kiss a post, or throw it into the fire... (from Gulliver's Travels)