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SQLite (http://www.sqlite.org/docs.html) 是一个轻量级的关系数据库。iOS SDK很早就支持了SQLite，在使用时，只需要加入 libsqlite3.dylib 依赖以及引入 sqlite3.h 头文件即可。但是，原生的SQLite API在使用上相当不友好，在使用时，非常不便。于是，开源社区中就出现了一系列将SQLite API进行封装的库，而FMDB (https://github.com/ccgus/fmdb) 则是开源社区中的优秀者。
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。
| 1 | +(NSString *)databaseFilePath |
| 2 | { |
| 3 | |
| 4 | NSArray *filePath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); |
| 5 | NSString *documentPath = [filePath objectAtIndex:0]; |
| 6 | NSLog(@"%@",filePath); |
| 7 | NSString *dbFilePath = [documentPath stringByAppendingPathComponent:@"db.sqlite"]; |
| 8 | return dbFilePath; |
| 9 | |
| 10 | } |
3、创建数据库的操作
| 1 | +(void)creatDatabase |
| 2 | { |
| 3 | db = [[FMDatabasedatabaseWithPath:[selfdatabaseFilePath]] retain]; |
| 4 | } |
4、创建表
| 1 | +(void)creatTable |
| 2 | { |
| 3 | //先判断数据库是否存在，如果不存在，创建数据库 |
| 4 | if (!db) { |
| 5 | [selfcreatDatabase]; |
| 6 | } |
| 7 | //判断数据库是否已经打开，如果没有打开，提示失败 |
| 8 | if (![db open]) { |
| 9 | NSLog(@"数据库打开失败"); |
| 10 | return; |
| 11 | } |
| 12 | |
| 13 | //为数据库设置缓存，提高查询效率 |
| 14 | [dbsetShouldCacheStatements:YES]; |
| 15 | |
| 16 | //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 |
| 17 | if(![dbtableExists:@"people"]) |
| 18 | { |
| 19 | [db executeUpdate:@"CREATE TABLES people(people_id INTEGER PRIMARY KEY AUTOINCREAMENT, name TEXT, age INTEGER) "]; |
| 20 | |
| 21 | |
| 22 | NSLog(@"创建完成"); |
| 23 | } |
| 24 | |
| 25 | } |
5、增加表数据
| 1 | +(void)insertPeople:(People *)aPeople |
| 2 | { |
| 3 | if (!db) { |
| 4 | [selfcreatDatabase]; |
| 5 | } |
| 6 | |
| 7 | if (![db open]) { |
| 8 | NSLog(@"数据库打开失败"); |
| 9 | return; |
| 10 | } |
| 11 | |
| 12 | [dbsetShouldCacheStatements:YES]; |
| 13 | |
| 14 | if(![dbtableExists:@"people"]) |
| 15 | { |
| 16 | [selfcreatTable]; |
| 17 | } |
| 18 | //以上操作与创建表是做的判断逻辑相同 |
| 19 | //现在表中查询有没有相同的元素，如果有，做修改操作 |
| 20 | FMResultSet *rs = [dbexecuteQuery:@"select * from people where people_id = ?",[NSStringstringWithFormat:@"%d",aPeople.peopleID]]; |
| 21 | if([rs next]) |
| 22 | { |
| 23 | NSLog(@"dddddslsdkien"); |
| 24 | [dbexecuteUpdate:@"update people set name = ?, age = ? where people_id = 1",aPeople.name,[NSStringstringWithFormat:@"%d",aPeople.age]]; |
| 25 | } |
| 26 | //向数据库中插入一条数据 |
| 27 | else{ |
| 28 | [dbexecuteUpdate:@"INSERT INTO people (name, age) VALUES (?,?)",aPeople.name,[NSStringstringWithFormat:@"%d",aPeople.age]]; |
| 29 | } |
| 30 | |
| 31 | } |
6、删除数据
| 1 | +(void)deletePeopleByID:(int)ID |
| 2 | { |
| 3 | if (!db) { |
| 4 | [selfcreatDatabase]; |
| 5 | } |
| 6 | |
| 7 | if (![db open]) { |
| 8 | NSLog(@"数据库打开失败"); |
| 9 | return; |
| 10 | } |
| 11 | |
| 12 | [dbsetShouldCacheStatements:YES]; |
| 13 | |
| 14 | //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 |
| 15 | if(![dbtableExists:@"people"]) |
| 16 | { |
| 17 | return; |
| 18 | } |
| 19 | //删除操作 |
| 20 | [db executeUpdate:@"delete from people where people_id = ?", [NSStringstringWithFormat:@"%d",ID]]; |
| 21 | |
| 22 | [db close]; |
| 23 | } |
7、修改操作与增加操作的步骤一致
8、查询
| 1 | +(NSArray *)getAllPeople |
| 2 | { |
| 3 | |
| 4 | if (!db) { |
| 5 | [selfcreatDatabase]; |
| 6 | } |
| 7 | |
| 8 | if (![db open]) { |
| 9 | NSLog(@"数据库打开失败"); |
| 10 | return nil; |
| 11 | } |
| 12 | |
| 13 | [dbsetShouldCacheStatements:YES]; |
| 14 | |
| 15 | if(![dbtableExists:@"people"]) |
| 16 | { |
| 17 | return nil; |
| 18 | } |
| 19 | |
| 20 | //定义一个可变数组，用来存放查询的结果，返回给调用者 |
| 21 | NSMutableArray *peopleArray = [[NSMutableArrayalloc] initWithArray:0]; |
| 22 | //定义一个结果集，存放查询的数据 |
| 23 | FMResultSet *rs = [dbexecuteQuery:@"select * from people"]; |
| 24 | //判断结果集中是否有数据，如果有则取出数据 |
| 25 | while ([rs next]) { |
| 26 | People *aPeople = [[People alloc] init]; |
| 27 | |
| 28 | aPeople.peopleID = [rs intForColumn:@"people_id"]; |
| 29 | aPeople.name = [rs stringForColumn:@"name"]; |
| 30 | aPeople.age = [rs intForColumn:@"age"]; |
| 31 | //将查询到的数据放入数组中。 |
| 32 | [peopleArray addObject:aPeople]; |
| 33 | } |
| 34 | return [peopleArray autorelease]; |
| 35 | } |
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原文地址：http://www.cnblogs.com/huangzs/p/4600653.html
