I'm trying to write up a document on the whole sqlite3_bind_pointer() thing now, that describes its motivation and its limitations. Hopefully that will clear up the confusion. I will announce when the new document goes up and request clearance from petern and kmedcalf prior to the release.
On 7/17/17, Keith Medcalf <[email protected]> wrote: > > On Monday, 17 July, 2017 08:00, Richard Hipp <[email protected]> wrote: >> On 7/17/17, Keith Medcalf <[email protected]> wrote: > >> > Also, a question. sqlite3_bind_pointer(C, P, T) and >> > sqlite3_value_pointer(C, P, T) indicates that T should be a "static >> > string". > >> > Does this mean of type SQLITE_STATIC and that it cannot be a string >> > located on the stack (ie, an SQLITE_TRANSIENT), or is a copy made of >> > the string value (ala SQLITE_TRANSIENT) for future use? > >> No copy is made of the string. SQLite merely keeps a pointer. If the >> memory that holds the string is deallocated or reused for some other >> purpose, bad things will happen. > > Ok, understand. I presume therefore that this is NOT a database type but is > for passing around value types and contexts only. Therefore using a > quoted-string will point to something in the global string table built by > the compiler and therefore be static. Makes sense. > > So if the sqlite3_bind_pointer is used to bind into a database column, that > value will be null when stored in the database? I suppose I could just try > this, but I thought I would ask you just to be sure ... > > Example: > > prepare("insert into table (col1, col2) values (?,?)") > bind_int64(...,1,intval) > bind_pointer(...,2,&intval, "carray") > step() > > that col1 gets the integer and col2 gets a NULL? and that the bind_pointer > actual pointer value and type string is only accessible when the bound > column is accessed by something that uses the used the sqlite3_value type > interfaces (that does not actually originate or terminate as a database row > -- and the pointer type is not preserved in the database itself but would be > persisted as if NULL?) > > > > > _______________________________________________ > sqlite-users mailing list > [email protected] > http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users > -- D. Richard Hipp [email protected] _______________________________________________ sqlite-users mailing list [email protected] http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
