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];

}

原文地址：http://www.cnblogs.com/lzz900201/archive/2012/11/06/2756284.html