MySQL嵌入式版本的小程序例子

MySQL嵌入式版本越來越式微了。碰巧有個小應用用到了它，順便記錄一下。
文檔可以參考http://dev.mysql.com/doc/refman/5.6/en/libmysqld-example.html，看起來年久失修的樣子，沒法一看就懂。
希望下面這個簡化的步驟可以起到點作用。
1. 下載代碼並且進行版本編譯。這個還比較簡單，文檔說的也很靠譜。
$ cmake . -DCMAKE_INSTALL_PREFIX=/home/mysql -DWITH_EMBEDDED_SERVER=1
$ make clean $ make -j 8
$ make install

2. 寫個小程序
$ ls
GNUmakefile main.cc my.cnf
具體代碼就看附件好了，其實很簡單。
$ make

3. 安裝好MySQL，初始化一下
$ cd /home/mysql
$ scripts/mysql_install_db --defaults-file=/home/mysql/my.cnf

4. 啟動小程序
$ ./main
附件：

# This assumes the MySQL software is installed in /usr/local/mysql
#inc      := /usr/local/mysql/include/mysql
#lib      := /usr/local/mysql/lib

# If you have not installed the MySQL software yet, try this instead
topdir   := /home/mysql/mysql-5.5.35
inc      := $(topdir)/include
lib      := $(topdir)/libmysqld

CXX      := g++
CPPFLAGS := -I$(inc) -D_THREAD_SAFE -D_REENTRANT
CXXFLAGS := -g -Wall
LDFLAGS  := 
# You can change -lmysqld to -lmysqlclient to use the
# client/server library
LDLIBS    = -L$(lib) -lmysqld -lm -lcrypt -ldl -lz -lrt

ifneq (,$(shell grep FreeBSD /COPYRIGHT 2>/dev/null))
# FreeBSD
LDFLAGS += -pthread
else
# Assume Linux
LDLIBS += -pthread
endif

# This works for simple one-file test programs
sources := $(wildcard *.cc)
objects := $(patsubst %cc,%o,$(sources))
targets := $(basename $(sources))

all: $(targets)

clean:
	rm -f $(targets) $(objects) *.core

---
#include <mysql.h>
#include <iostream>
#include <cassert>

using namespace std;

const char *server_options[] = \
       { "mysql_test", "--defaults-file=my.cnf", NULL };
int num_elements = (sizeof(server_options) / sizeof(char *)) - 1;

const char *server_groups[]= { "libmysqld_server",
                               "libmysqld_client",
                               NULL};

bool is_server_started= false;

MYSQL *MySQL= NULL;

const char *db= NULL;

void start_server()
{
  cout << "enter start_server()" << endl;
  if (mysql_library_init(num_elements, (char **) server_options, (char **) server_groups)) {
    is_server_started= false;
    cout << "ERROR: start server failed." << endl;
  }
  else {
    is_server_started= true;
    cout << "INFO: start server OK." << endl;
  }
}

void stop_server()
{
  cout << "enter stop_server()" << endl;
  mysql_server_end();
}

bool connect_server()
{
  cout << "enter connect_server()" << endl;
  bool rc = true;

  MySQL = mysql_init(NULL);
  if (!MySQL)
    return rc;

  if (mysql_real_connect(MySQL, NULL, NULL, NULL, db, 0, NULL, 0))
    rc = false;
 
  MySQL->reconnect= 1;
  return rc;
}

void output_rows(MYSQL_RES *res)
{
  MYSQL_ROW row;
  unsigned long n = 0;

  while ((row= mysql_fetch_row(res)) != 0)
  {
    mysql_field_seek(res, 0);
    for (unsigned int i= 0 ; i < mysql_num_fields(res); i++)
      cout << "row[" << n++ << "]:"<< row[i] << endl; 
  }
}

bool get_dbs()
{
  MYSQL_RES *res;

  if (!is_server_started)
    return true;

  if (!(res= mysql_list_dbs(MySQL, "%")))
    return true;

  output_rows(res);
  mysql_free_result(res);
  return false;
}

int main(int argc, char *argv[])
{
  start_server();
  if (is_server_started) {
    cout << "server started." << endl;
    if (!connect_server()) {
      get_dbs();
    }
    stop_server();
  }

  return 0;
}

---
[libmysqld_client]

[libmysqld_server]
basedir=/home/mysql/
datadir=/home/mysql/data
tmpdir=/home/mysql/tmp
log-error=/home/mysql/alert.log
lc_messages_dir=/home/mysql/share

innodb_data_home_dir=/home/mysql/data
innodb_log_group_home_dir=/home/mysql/data