The comment approach could work, I guess, but why not just encode the type into the column's declared type?
CREATE TABLE blob_table ( ModelNo TEXT, SerialNo TEXT, VSWR BLOB_DOUBLE ) That's what I do with numeric columns that I need to identify as actually containing dates. As I understand it, SQLite only scans those type names to choose a column affinity, so you are free to be as creative with them as you want. sqlite3_column_decltype() will return whatever you put as the type. HTH, Eric Sent from Windows Mail From: William Drago<mailto:wdr...@suffolk.lib.ny.us> Sent: ?Saturday?, ?May? ?9?, ?2015 ?7?:?18? ?AM To: sqlite-users at mailinglists.sqlite.org<mailto:sqlite-users at mailinglists.sqlite.org> On 5/9/2015 6:40 AM, Eduardo Morras wrote: > On Sat, 09 May 2015 06:09:41 -0400 > William Drago <wdrago at suffolk.lib.ny.us> wrote: > >> All, >> >> Say you encounter a blob in a database. There's no way to >> tell if that blob carries bytes, floats, doubles, etc, correct? >> >> Assuming the above is true, then is it always prudent to >> store some metadata along with your blobs so that they can >> be identified in the future? >> >> Example table: >> >> ModelNo TEXT (e.g. SO-239) >> SerialNo TEXT (e.g. 101) >> VSWR BLOB (e.g. x'feab12c...') >> VSWR_Type TEXT (e.g. double) >> >> >> Does this make sense? > You can use SQL comments on CREATE TABLE, those comments aren't deleted from > SQLITE_MASTER table, you can query it as a normal table. > > CREATE TABLE blob_table ( > ModelNo TEXT, -- e.g. S0-239 > SerialNo TEXT, -- e.g. 101 > VSWR BLOB -- double, e.g. x'feab12c....' > ); > > SELECT sql from sqlite_master where type='table' AND tbl_name='blob_table'; > > will return > > CREATE TABLE blob_table ( > ModelNo TEXT, -- e.g. S0-239 > SerialNo TEXT, -- e.g. 101 > VSWR BLOB -- double, e.g. x'feab12c....' > ) This is a clever idea and saves the addition of a column just for blob type. Is this a reliable feature of SQLite? Does anyone see any issues with this as opposed to using a dedicated column? Thanks, -Bill _______________________________________________ sqlite-users mailing list sqlite-users at mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
