Author: wyoung
Date: Tue Jun 19 06:30:31 2007
New Revision: 1563
URL: http://svn.gna.org/viewcvs/mysqlpp?rev=1563&view=rev
Log:
- Added examples/store_if.cpp to test Query::store_if().
- Added Query::for_each() and Query::store_if(), suggested by Joel
Fielder <[EMAIL PROTECTED]>. (Code's all mine.)
- Added examples/store_if.cpp to test Query::store_if().
- Added Joel to the credits list.
Added:
trunk/examples/store_if.cpp
- copied, changed from r1559, trunk/examples/usequery.cpp
Modified:
trunk/ (props changed)
trunk/CREDITS
trunk/lib/query.h
trunk/mysql++.bkl
Propchange: trunk/
------------------------------------------------------------------------------
--- svn:ignore (original)
+++ svn:ignore Tue Jun 19 06:30:31 2007
@@ -44,6 +44,7 @@
multiquery
resetdb
simple[0-9]
+store_if
tquery
updel
usequery
Modified: trunk/CREDITS
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/CREDITS?rev=1563&r1=1562&r2=1563&view=diff
==============================================================================
--- trunk/CREDITS (original)
+++ trunk/CREDITS Tue Jun 19 06:30:31 2007
@@ -36,6 +36,10 @@
Remi Collet <[EMAIL PROTECTED]> is maintaining offical
RPMs for Fedora, with other systems on the way. His work has
improved the RPM spec file we distribute greatly.
+
+ Joel Fielder <[EMAIL PROTECTED]> came up with the
+ original idea for Query::for_each() and Query::store_in(), and
+ provided a fix for exception flag propagation in Query.
Here are the personal credits from the old 1.7.9 documentation,
Copied: trunk/examples/store_if.cpp (from r1559, trunk/examples/usequery.cpp)
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/examples/store_if.cpp?p2=trunk/examples/store_if.cpp&p1=trunk/examples/usequery.cpp&r1=1559&r2=1563&rev=1563&view=diff
==============================================================================
--- trunk/examples/usequery.cpp (original)
+++ trunk/examples/store_if.cpp Tue Jun 19 06:30:31 2007
@@ -1,8 +1,10 @@
/***********************************************************************
- usequery.cpp - Same as simple2 example, only with exceptions enabled.
- The end of the result set is signalled differently in this case.
+ store_if.cpp - Demonstrates Query::store_if(), showing only the rows
+ from the sample table with prime quantities. This isn't intended
+ to be useful, only to show how you can do result set filtering that
+ outstrips the power of SQL.
- Copyright (c) 2005 by Educational Technology Resources, Inc.
+ Copyright (c) 2005-2007 by Educational Technology Resources, Inc.
Others may also hold copyrights on code in this file. See the CREDITS
file in the top directory of the distribution for details.
@@ -25,10 +27,37 @@
***********************************************************************/
#include "util.h"
+#include "stock.h"
#include <mysql++.h>
#include <iostream>
+
+
+// Define a functor for testing primality.
+struct is_prime
+{
+ bool operator()(const stock& s)
+ {
+ if ((s.num == 2) || (s.num == 3)) {
+ return true; // 2 and 3 are trivial cases
+ }
+ else if ((s.num < 2) || ((s.num % 2) == 0)) {
+ return false; // can't be prime if < 2 or even
+ }
+ else {
+ // The only possibility left is that it's divisible by
an
+ // odd number that's less or equal to its square root.
+ for (int i = 3; i <= sqrt(s.num); i += 2) {
+ if ((s.num % i) == 0) {
+ return false;
+ }
+ }
+ return true;
+ }
+ }
+};
+
int
main(int argc, char *argv[])
@@ -40,21 +69,17 @@
return 1;
}
- // Build query to retrieve the entire stock table
+ // Pull only the stock items with prime quantities
+ std::vector<stock> results;
mysqlpp::Query query = con.query();
- query << "select * from stock";
+ query.store_if(results, "select * from stock", is_prime());
- // Execute the query, but don't save results in memory
- mysqlpp::ResUse res = query.use();
- if (!res) {
- std::cerr << "Result set is empty!" << std::endl;
- return 1;
- }
-
- // Iterate through result set, printing each row.
- mysqlpp::Row r;
- while (r = res.fetch_row()) {
- print_stock_row(r);
+ // Show the results
+ print_stock_header(results.size());
+ std::vector<stock>::const_iterator it;
+ for (it = results.begin(); it != results.end(); ++it) {
+ print_stock_row(it->item.c_str(), it->num, it->weight,
+ it->price, it->sdate);
}
}
catch (const mysqlpp::BadQuery& e) {
@@ -62,18 +87,11 @@
std::cerr << "Query failed: " << e.what() << std::endl;
return 1;
}
- catch (const mysqlpp::EndOfResults&) {
- // Last query result received. Exit normally.
- return 0;
- }
catch (const mysqlpp::Exception& er) {
// Catch-all for any other MySQL++ exceptions
std::cerr << "Error: " << er.what() << std::endl;
return 1;
}
- // Shouldn't happen! Program should either error out through one of
- // the "return 1" cases above, or successfully walk off the end of
- // the result set and go through the EndOfResults path above.
- return 2;
+ return 0;
}
Modified: trunk/lib/query.h
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/lib/query.h?rev=1563&r1=1562&r2=1563&view=diff
==============================================================================
--- trunk/lib/query.h (original)
+++ trunk/lib/query.h Tue Jun 19 06:30:31 2007
@@ -370,6 +370,65 @@
/// than use(), but it lets you have random access to the results.
Result store(const char* str, size_t len);
+ /// \brief Execute a query, and call a functor for each returned row
+ ///
+ /// This method wraps a use() query, calling the given functor for
+ /// every returned row. It is analogous to STL's for_each()
+ /// algorithm, but instead of iterating over some range within a
+ /// container, it iterates over a result set produced by a query.
+ ///
+ /// \param query the query string
+ /// \param fn the functor called for each row
+ /// \return a copy of the passed functor
+ template <typename Function>
+ Function for_each(const SQLString& query, Function fn)
+ {
+ mysqlpp::ResUse res = use(query);
+ if (res) {
+ mysqlpp::NoExceptions ne(*this);
+ while (mysqlpp::Row row = res.fetch_row()) {
+ fn(row);
+ }
+ }
+
+ return fn;
+ }
+
+ /// \brief Execute a query, conditionally storing each row in a
+ /// container
+ ///
+ /// This method wraps a use() query, calling the given functor for
+ /// every returned row, and storing the results in the given
+ /// sequence container if the functor returns true.
+ ///
+ /// This is analogous to the STL copy_if() algorithm, except that
+ /// the source rows come from a database query instead of another
+ /// container. (copy_if() isn't a standard STL algorithm, but only
+ /// due to an oversight by the standardization committee.) This
+ /// fact may help you to remember the order of the parameters: the
+ /// container is the destination, the query is the source, and the
+ /// functor is the predicate; it's just like an STL algorithm.
+ ///
+ /// \param seq the destination container; needs a push_back() method
+ /// \param query the query string
+ /// \param fn the functor called for each row
+ /// \return a copy of the passed functor
+ template <class Sequence, typename Function>
+ Function store_if(Sequence& seq, const SQLString& query, Function fn)
+ {
+ mysqlpp::NoExceptions ne(*this);
+ mysqlpp::ResUse res = use(query);
+ if (res) {
+ while (mysqlpp::Row row = res.fetch_row()) {
+ if (fn(row)) {
+ seq.push_back(row);
+ }
+ }
+ }
+
+ return fn;
+ }
+
/// \brief Return next result set, when processing a multi-query
///
/// There are two cases where you'd use this function instead of
Modified: trunk/mysql++.bkl
URL:
http://svn.gna.org/viewcvs/mysqlpp/trunk/mysql%2B%2B.bkl?rev=1563&r1=1562&r2=1563&view=diff
==============================================================================
--- trunk/mysql++.bkl (original)
+++ trunk/mysql++.bkl Tue Jun 19 06:30:31 2007
@@ -240,6 +240,9 @@
<exe id="xaction" template="util-example,common-example">
<sources>examples/xaction.cpp</sources>
</exe>
+ <exe id="store_if" template="util-example,common-example">
+ <sources>examples/store_if.cpp</sources>
+ </exe>
<!-- The few examples that don't use the util module -->
<exe id="cgi_jpeg" template="common-example">
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