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 22.2.16.6 A Simple Embedded Server Example
 ..........................................
 
 This example program and makefile should work without any changes on a
 Linux or FreeBSD system.  For other operating systems, minor changes
 will be needed.  This example is designed to give enough details to
 understand the problem, without the clutter that is a necessary part of
 a real application.
 
 To try out the example, create an `test_libmysqld' directory at the
 same level as the mysql-4.0 source directory.  Save the
 `test_libmysqld.c' source and the `GNUmakefile' in the directory, and
 run GNU `make' from inside the `test_libmysqld' directory.
 
 `test_libmysqld.c'
      /*
       * A simple example client, using the embedded MySQL server library
       */
 
      #include <mysql.h>
      #include <stdarg.h>
      #include <stdio.h>
      #include <stdlib.h>
 
      MYSQL *db_connect(const char *dbname);
      void db_disconnect(MYSQL *db);
      void db_do_query(MYSQL *db, const char *query);
 
      const char *server_groups[] = {
        "test_libmysqld_SERVER", "embedded", "server", NULL
      };
 
      int
      main(int argc, char **argv)
      {
        MYSQL *one, *two;
 
        /* mysql_server_init() must be called before any other mysql
         * functions.
         *
         * You can use mysql_server_init(0, NULL, NULL), and it will
         * initialize the server using groups = {
         *   "server", "embedded", NULL
         *  }.
         *
         * In your $HOME/.my.cnf file, you probably want to put:
 
      [test_libmysqld_SERVER]
      language = /path/to/source/of/mysql/sql/share/english
 
         * You could, of course, modify argc and argv before passing
         * them to this function.  Or you could create new ones in any
         * way you like.  But all of the arguments in argv (except for
         * argv[0], which is the program name) should be valid options
         * for the MySQL server.
         *
         * If you link this client against the normal mysqlclient
         * library, this function is just a stub that does nothing.
         */
        mysql_server_init(argc, argv, (char **)server_groups);
 
        one = db_connect("test");
        two = db_connect(NULL);
 
        db_do_query(one, "SHOW TABLE STATUS");
        db_do_query(two, "SHOW DATABASES");
 
        mysql_close(two);
        mysql_close(one);
 
        /* This must be called after all other mysql functions */
        mysql_server_end();
 
        exit(EXIT_SUCCESS);
      }
 
      static void
      die(MYSQL *db, char *fmt, ...)
      {
        va_list ap;
        va_start(ap, fmt);
        vfprintf(stderr, fmt, ap);
        va_end(ap);
        (void)putc('\n', stderr);
        if (db)
          db_disconnect(db);
        exit(EXIT_FAILURE);
      }
 
      MYSQL *
      db_connect(const char *dbname)
      {
        MYSQL *db = mysql_init(NULL);
        if (!db)
          die(db, "mysql_init failed: no memory");
        /*
         * Notice that the client and server use separate group names.
         * This is critical, because the server will not accept the
         * client's options, and vice versa.
         */
        mysql_options(db, MYSQL_READ_DEFAULT_GROUP, "test_libmysqld_CLIENT");
        if (!mysql_real_connect(db, NULL, NULL, NULL, dbname, 0, NULL, 0))
          die(db, "mysql_real_connect failed: %s", mysql_error(db));
 
        return db;
      }
 
      void
      db_disconnect(MYSQL *db)
      {
        mysql_close(db);
      }
 
      void
      db_do_query(MYSQL *db, const char *query)
      {
        if (mysql_query(db, query) != 0)
          goto err;
 
        if (mysql_field_count(db) > 0)
        {
          MYSQL_RES   *res;
          MYSQL_ROW    row, end_row;
          int num_fields;
 
          if (!(res = mysql_store_result(db)))
            goto err;
          num_fields = mysql_num_fields(res);
          while ((row = mysql_fetch_row(res)))
          {
            (void)fputs(">> ", stdout);
            for (end_row = row + num_fields; row < end_row; ++row)
              (void)printf("%s\t", row ? (char*)*row : "NULL");
            (void)fputc('\n', stdout);
          }
          (void)fputc('\n', stdout);
          mysql_free_result(res);
        }
        else
          (void)printf("Affected rows: %lld\n", mysql_affected_rows(db));
 
        return;
 
      err:
        die(db, "db_do_query failed: %s [%s]", mysql_error(db), query);
      }
 
 `GNUmakefile'
      # 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
      #inc      := $(HOME)/mysql-4.0/include
      #lib      := $(HOME)/mysql-4.0/libmysqld
 
      CC       := gcc
      CPPFLAGS := -I$(inc) -D_THREAD_SAFE -D_REENTRANT
      CFLAGS   := -g -W -Wall
      LDFLAGS  := -static
      # You can change -lmysqld to -lmysqlclient to use the
      # client/server library
      LDLIBS    = -L$(lib) -lmysqld -lz -lm -lcrypt
 
      ifneq (,$(shell grep FreeBSD /COPYRIGHT 2>/dev/null))
      # FreeBSD
      LDFLAGS += -pthread
      else
      # Assume Linux
      LDLIBS += -lpthread
      endif
 
      # This works for simple one-file test programs
      sources := $(wildcard *.c)
      objects := $(patsubst %c,%o,$(sources))
      targets := $(basename $(sources))
 
      all: $(targets)
 
      clean:
              rm -f $(targets) $(objects) *.core
 

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