iOS关于数据库的操作（使用第三方类库FMDB）
- 首先要先导入第三方类库FMdatabase
- 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;}
- 创建数据库的操作
+(void)creatDatabase
{
db = [[FMDatabasedatabaseWithPath:[selfdatabaseFilePath]] retain];
}
- 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");}
- 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 = [dbexecuteQuery:@"select * from people where people_id = ?",[NSStringstringWithFormat:@"%d",aPeople.peopleID]];if([rs next])
{
NSLog(@"dddddslsdkien");
}
[dbexecuteUpdate:@"update people set name = ?, age = ? where people_id = 1",aPeople.name,[NSStringstringWithFormat:@"%d",aPeople.age]];
//向数据库中插入一条数据
else{[dbexecuteUpdate:@"INSERT INTO people (name, age) VALUES (?,?)",aPeople.name,[NSStringstringWithFormat:@"%d",aPeople.age]];
}}
- 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 = ?", [NSStringstringWithFormat:@"%d",ID]];
[db close];}
- 修改操作与增加操作的步骤一致
- 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 = [[NSMutableArrayalloc] initWithArray:0];//定义一个结果集，存放查询的数据
FMResultSet *rs = [dbexecuteQuery:@"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];}
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