:- use_module(library(odbc)).(can be autoloaded)
fetch(fetch)and be executed using odbc_execute/2. Row is unified to the fetched row or the atom
end_of_file6This atom was selected to emphasise the similarity to read. after the end of the data is reached. Calling odbc_fetch/2 after all data is retrieved causes a permission-error exception. Option is one of:
- Fetch the next row.
- Fetch the result-set going backwards.
- Fetch the first row.
- Fetch the last row.
- Fetch absolute numbered row. Rows count from one.
- Fetch relative to the current row.
relative(1)is the same as
next, except that the first row extracted is row 2.
- Reserved. Bookmarks are not yet supported in this interface.
In many cases, depending on the driver and RDBMS, the cursor-type
must be changed using odbc_set_connection/2
for anything different from
next to work.
Here is example code each time skipping a row from a table‘test' holding a single column of integers that represent the row-number. This test was executed using unixODBC and MySQL on SuSE Linux.
fetch(Options) :- odbc_set_connection(test, cursor_type(static)), odbc_prepare(test, 'select (testval) from test', , Statement, [ fetch(fetch) ]), odbc_execute(Statement, ), fetch(Statement, Options). fetch(Statement, Options) :- odbc_fetch(Statement, Row, Options), ( Row == end_of_file -> true ; writeln(Row), fetch(Statement, Options) ).