FMDB的使用

1. 首先要先导入第三方类库FMdatabase

2. 获得存放数据库文件的沙盒地址

   +(NSString *)databaseFilePath

   {

   
   

   NSArray *filePath = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory , NSUserDomainMask , YES );
   NSString *documentPath = [filePath objectAtIndex: 0];
   NSLog( @"%@",filePath);
   NSString *dbFilePath = [documentPath stringByAppendingPathComponent: @"db.sqlite"];
   return dbFilePath;

   
   

   }

   
   

3. 创建数据库的操作

   +(void)creatDatabase

   {

   db = [[ FMDatabasedatabaseWithPath :[ selfdatabaseFilePath ]] retain ];

   }

   
   

4. 创建表

   +(void)creatTable

   {

   //先判断数据库是否存在，如果不存在，创建数据库

   if (! db) {
   

   [ selfcreatDatabase ];
   

   }
   //判断数据库是否已经打开，如果没有打开，提示失败
   if (![ db open]) {
   

   NSLog (@" 数据库打开失败" );
   return ;
   

   }
   
   

   //为数据库设置缓存，提高查询效率
   [ dbsetShouldCacheStatements : YES ];
   

   //判断数据库中是否已经存在这个表，如果不存在则创建该表
   if (![ dbtableExists : @"people" ])
   {
   

   [ db executeUpdate :@"CREATE TABLES people(people_id INTEGER PRIMARY KEY AUTOINCREAMENT, name TEXT, age INTEGER) " ];
   
   
   NSLog (@" 创建完成" );
   

   }

   
   

   }

   
   

5. 增加表数据

   +(void)insertPeople:(People *)aPeople

   {

   if (! db) {
   

   [ selfcreatDatabase ];
   

   }
   
   if (![ db open]) {
   

   NSLog (@" 数据库打开失败" );
   return ;
   

   }
   
   [ dbsetShouldCacheStatements : YES ];
   
   if (![ dbtableExists : @"people" ])
   {
   

   [ selfcreatTable ];
   

   }
   //以上操作与创建表是做的判断逻辑相同

   //现在表中查询有没有相同的元素，如果有，做修改操作
   FMResultSet *rs = [ db executeQuery :@"select * from people where people_id = ?" ,[ NSString stringWithFormat :@"%d" ,aPeople. peopleID ]];
   

   if([rs next])

   {
   

   NSLog (@"dddddslsdkien" );
   [ db executeUpdate :@"update people set name = ?, age = ? where people_id = 1" ,aPeople. name ,[ NSString stringWithFormat :@"%d" ,aPeople. age ]];
   

   }
   //向数据库中插入一条数据
   else {
   

   [ db executeUpdate :@"INSERT INTO people (name, age) VALUES (?,?)" ,aPeople. name ,[ NSString stringWithFormat :@"%d" ,aPeople. age ]];
   

   }

   
   

   
   

   }

   
   

6. 删除数据

   +(void)deletePeopleByID:(int)ID

   {

   if (! db) {
   

   [ selfcreatDatabase ];
   

   }
   
   if (![ db open]) {
   

   NSLog (@" 数据库打开失败" );
   return ;
   

   }
   
   [ dbsetShouldCacheStatements : YES ];
   

   //判断表中是否有指定的数据， 如果没有则无删除的必要，直接return
   if (![ dbtableExists : @"people" ])
   {
   

   return ;
   

   }
   //删除操作
   [ db executeUpdate :@"delete from people where people_id = ?" , [ NSString stringWithFormat :@"%d" ,ID]];
   
   [ db close];

   }

   
   

7. 修改操作与增加操作的步骤一致

8. 查询

   +(NSArray *)getAllPeople

   {

   
   if (! db) {
   

   [ selfcreatDatabase ];
   

   }
   
   if (![ db open]) {
   

   NSLog (@" 数据库打开失败" );
   return nil ;
   

   }
   
   [ dbsetShouldCacheStatements : YES ];
   
   if (![ dbtableExists : @"people" ])
   {
   

   return nil ;
   

   }
   
   

   //定义一个可变数组，用来存放查询的结果，返回给调用者
   NSMutableArray *peopleArray = [[NSMutableArray alloc ] initWithArray : 0 ];

   //定义一个结果集，存放查询的数据
   FMResultSet *rs = [ db executeQuery :@"select * from people" ];

   //判断结果集中是否有数据，如果有则取出数据
   while ([rs next]) {
   

   People *aPeople = [[ People alloc] init];
   
   aPeople. peopleID = [rs intForColumn: @"people_id"];
   aPeople. name = [rs stringForColumn: @"name"];
   aPeople. age = [rs intForColumn: @"age"];
   //将查询到的数据放入数组中。
   [peopleArray addObject:aPeople];

   }
   return [peopleArray autorelease];

   }