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Db::set_append_recno
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#include &lt;db_cxx.h&gt;

int
Db::set_append_recno(int (*db_append_recno_fcn)(DB *dbp, Dbt *data, db_recno_t recno));
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Description: Db::set_append_recno
When using the <a href="../../db4-devel-4.7.25/api_cxx/db_put.html#DB_APPEND">DB_APPEND</a> option of the <a href="../../db4-devel-4.7.25/api_cxx/db_put.html">Db::put</a> method,
it may be useful to modify the stored data based on the generated key.
If a callback function is specified using the
Db::set_append_recno method, it will be called after the record number
has been selected, but before the data has been stored.
The Db::set_append_recno method configures operations performed using the specified
<a href="../../db4-devel-4.7.25/api_cxx/db_class.html">Db</a> handle, not all operations performed on the underlying
database.
The Db::set_append_recno method may not be called after the <a href="../../db4-devel-4.7.25/api_cxx/db_open.html">Db::open</a> method is called.

The Db::set_append_recno method
either returns a non-zero error value
or throws an exception that encapsulates a non-zero error value on
failure, and returns 0 on success.

Parameters 
 db_append_recno_fcn<ul compact><li>The db_append_recno_fcn parameter is a function to call after
the record number has been selected but before the data has been stored
into the database. The function takes three parameters:
 
db<ul compact><li>The db parameter is the enclosing database handle.</ul>
dbt<ul compact><li>The dbt parameter is the data <a href="../../db4-devel-4.7.25/api_cxx/dbt_class.html">Dbt</a> to be stored.</ul>
recno<ul compact><li>The recno parameter is the generated record number.</ul>
 
The called function may modify the data <a href="../../db4-devel-4.7.25/api_cxx/dbt_class.html">Dbt</a>. If the function
needs to allocate memory for the data field, the flags
field of the returned <a href="../../db4-devel-4.7.25/api_cxx/dbt_class.html">Dbt</a> should be set to
DB_DBT_APPMALLOC, which indicates that Berkeley DB should free the
memory when it is done with it.
The callback function must return 0 on success and errno or
a value outside of the Berkeley DB error name space on failure.
Berkeley DB is not re-entrant. Callback functions should not attempt to make
library calls (for example, to release locks or close open handles).
Re-entering Berkeley DB is not guaranteed to work correctly, and the results
are undefined.</ul>
 
 Errors
The Db::set_append_recno method
may fail and throw
<a href="../../db4-devel-4.7.25/api_cxx/except_class.html">DbException</a>,
encapsulating one of the following non-zero errors, or return one of
the following non-zero errors:
 
EINVAL<ul compact><li>If the method was called after <a href="../../db4-devel-4.7.25/api_cxx/db_open.html">Db::open</a> was called; or if an
invalid flag value or parameter was specified.</ul>
 
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 Class
<a href="../../db4-devel-4.7.25/api_cxx/db_class.html">Db</a>
 See Also
<a href="../../db4-devel-4.7.25/api_cxx/db_list.html">Databases and Related Methods</a>
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