FMDB-使用

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FMDB 增删改查

1. FMDB 优点:
   [1] 使用起来更加面向对象，省去了很多麻烦、冗余的C语言代码
   [2] 对比苹果自带的Core Data框架，更加轻量级和灵活
   [3] 提供了多线程安全的数据库操作方法，有效地防止数据混乱

2. 核心类
   [1] FMDatabase:
   一个FMDatabase对象就代表一个单独的SQLite数据库
   用来执行SQL语句
   [2] FMResultSet:
   使用FMDatabase执行查询后的结果集
   [3] FMDatabaseQueue:
   用于在多线程中执行多个查询或更新，它是线程安全的

#import "FMDBModel.h"
#import "FMDB.h"
// 创建数据库
NSString *create = @"CREATE TABLE IF NOT EXISTS t_GESTURE (iPhone text NOT NULL ,password text NOT NULL)";

//delete from是删除关键字，后面是要删的表名，然后可以选择跟一个where限制，限制参考修改
NSString *delete = @"delete from t_GESTURE where iPhone = ?";

//update是修改的关键字，后面是t_GESTURE表名，set表示修改动作的关键字，set后面跟着被改的字段名及其要改的内容(要改的内容也可以是?)，再后面可以加where限制，也可以不加，where后面是字段=内容的结构，内容同样可以为?
NSString *updateTable = @"update t_GESTURE set password = ? where iPhone = ?";

// 查询数据库
NSString *selectTable = @"SELECT * FROM t_GESTURE";

@interface FMDBModel ()
@property (nonatomic,strong) FMDatabase *db;
@end
@implementation FMDBModel
+(FMDBModel *)fModel{
static FMDBModel *fModel = nil;
  static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
    if (!fModel) {
         fModel = [[FMDBModel alloc] init];
        NSString *path = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"FMDB.sqlite"];
        FMDatabase *db = [FMDatabase databaseWithPath:path];
        [db open];
        NSLog(@"%@",path);
        [db executeUpdate:create];
        [db close];
        fModel.db = db;
    }
});
return  fModel;
}

- (void)insert{
[self.db open];
BOOL isInsert = [self.db executeUpdate:@"insert into t_GESTURE(iphone,password) VALUES (?,?)",self.phone,self.password];
if (isInsert) {
    NSLog(@"插入成功");
}
[self.db close];
}
- (void)Delete{
[self.db open];
//2、调用删除语句
BOOL isDelCharactor = [self.db executeUpdate:delete,self.phone];
if (isDelCharactor) {
    NSLog(@"成功");
}
[self.db close];
}
- (void)change{
[self.db open];
//2、调用修改语句
BOOL isUpdate = [self.db executeUpdate:updateTable,self.password,self.phone];
if(isUpdate == NO)
{
    NSLog(@"修改失败");
    return;
}else{
    NSLog(@"修改成功");
}
[self.db close];
}
- (void)query{
[self.db open];
// 查询
FMResultSet *resultSet = [self.db executeQuery:selectTable];
while ([resultSet next]) {
    NSString *phone = [resultSet stringForColumn:@"iPhone"];
    NSString *password = [resultSet stringForColumn:@"password"];
    NSLog(@" %@ %@",phone,password);
}
[self.db close];
}

使用

// 插入
- (IBAction)ConfirmDown:(id)sender {
[FMDBModel fModel].phone = self.iPhone.text;
[FMDBModel fModel].password = self.password.text;
[[FMDBModel fModel] insert];
}

// 查询
- (IBAction)SelectDown:(id)sender {
[[FMDBModel fModel] query];
}

// 删除
- (IBAction)Delete:(id)sender {
[FMDBModel fModel].phone = self.iPhone.text;
[FMDBModel fModel].password = self.password.text;
[[FMDBModel fModel] Delete];
}
// 修改
- (IBAction)change:(id)sender {
[FMDBModel fModel].phone = self.iPhone.text;
[FMDBModel fModel].password = self.password.text;
[[FMDBModel fModel] change];
}