iOS-----fmdb和简单的SQL语句运用

1.添加fmdb

• 点击这里下载fmdb
• 在项目中TARGETS->Build Phases ->Link Binary With Libraries 添加libsqlite3.tdb
• 把fmdb拖到自己的项目中 添加头文件 #import "DBManager.h"
• TARGETS->Build Phases ->Compile Sources 中找到FMDatabaseQueue.m 和FMDatabasePool.m，改为非arc (-fno-objc-arc)

这下运行fmdb就不会报错了

2.SQL语句

我项目中使用的代码

DBManager.h

#import 
#import "BookDetailModel.h"

@interface DBManager : NSObject

+ (DBManager *)shareManager;

//包含这条数据的话 我们显示取消收藏 没有这条数据的话 我们应该收藏
- (BOOL)isExistsDataWithModel:(BookDetailModel *)model;

//收藏 插入一条数据
- (BOOL)insertDataWithModel:(BookDetailModel *)model;

- (BOOL)deleteDataWithModel:(BookDetailModel *)model;

//更改一条数据
- (BOOL)changeDataWithModel:(BookDetailModel *)model newStr:(NSString *)str;

//返回所有数据
- (NSArray *)allData;

@end

DBManager.m

#import "DBManager.h"
#import "FMDatabase.h"

@implementation DBManager{
    //操作数据库的对象
    FMDatabase *_fmdb;
}

+ (DBManager *)shareManager{
    static DBManager *_dB = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        if (_dB == nil) {
            _dB = [[DBManager alloc] init];
        }
    });
    return _dB;
}

- (id)init{
    self = [super init];
    if (self) {
        //fmdb对象 他的实例化 需要一个路径
        //[NSBundle mainBundle]
        //user/Documents/photoshops/....
        //当使用 NSHomeDirectory() 你得到了3个文件夹（路径 你所在的地方有三个文件夹）
        //NSHomeDirectory() -> NSString
        NSString *path = [NSHomeDirectory() stringByAppendingString:@"/Documents/appa.db"];
        NSLog(@"打印数据库路径:%@",path);
        _fmdb = [[FMDatabase alloc] initWithPath:path];
        if ([_fmdb open]) {
            NSLog(@"打开数据库成功");
            //我们打开数据库之后 需要创建表格
            /*
             create table if not exists app(id varchar(32),name varchar(128),pic varchar(1024))
             */
            NSString *sql = @"create table if not exists app(_id varchar(32),updated varchar(128),cover varchar(1024),title varchar(128))";
            BOOL isSuccess = [_fmdb executeUpdate:sql];
            if (isSuccess) {
                NSLog(@"create Tabel Success");
            }else{
                NSLog(@"create Tabel Fail:%@",_fmdb.lastErrorMessage);
            }
            
        }else{
            NSLog(@"open Sqlite File");
        }
        
    }
    return self;
}

#pragma mark - 数据库操作
//这个表格里面是否包含这个数据
//查询
- (BOOL)isExistsDataWithModel:(BookDetailModel *)model{
    /*
     select applicationid from app where applicationid = ?
     */
    NSString *sql = @"select _id from app where _id = ?";
    //_fmdb
    //这个方法是查询
    FMResultSet *set = [_fmdb executeQuery:sql,model._id];
    
    //[set next] 如果你查询到了 这个方法会返回一个真值
    
    return [set next];
}

//插入
- (BOOL)insertDataWithModel:(BookDetailModel *)model{
    /*
     insert into app (applicationId,name,iconUrl) values (?,?,?)
     */

    NSString *sql = @"insert into app (_id,updated,cover,title) values (?,?,?,?)";
    BOOL isSuccess = [_fmdb executeUpdate:sql,model._id,model.updated,model.cover,model.title];
    if (isSuccess) {
        NSLog(@"插入成功");
    }else{
        NSLog(@"插入失败:%@",_fmdb.lastErrorMessage);
    }
    return isSuccess;
}


- (BOOL)deleteDataWithModel:(BookDetailModel *)model{
    NSString *sql = @"delete from app where _id = ?";
    BOOL isSuccess = [_fmdb executeUpdate:sql,model._id];
    if (isSuccess) {
        NSLog(@"删除成功");
    }else{
        NSLog(@"删除失败%@",_fmdb.lastErrorMessage);
    }
    return isSuccess;
}
//修改
//- (BOOL)changeDataWithModel:(BookDetailModel *)model newStr:(NSString *)str{
//    
//    NSString *sql = @"update app set name = ? where name = ?";
//    BOOL isSuccess = [_fmdb executeUpdate:sql,str,model.name];
//    if (isSuccess) {
//        NSLog(@"修改成功");
//    }else{
//        NSLog(@"修改失败:%@",_fmdb.lastErrorMessage);
//    }
//    return isSuccess;
//}

- (NSArray *)allData{
    NSString *sql = @"select * from app";
    FMResultSet *set = [_fmdb executeQuery:sql];
    //装数据模型
    NSMutableArray *array = [NSMutableArray array];
    while ([set next]) {
        BookDetailModel *model = [[BookDetailModel alloc] init];
        model.title = [set stringForColumn:@"title"];
        model._id = [set stringForColumn:@"_id"];
        model.cover = [set stringForColumn:@"cover"];
        model.updated = [set stringForColumn:@"updated"];
        [array addObject:model];
    }
    
    return array;
}

/*
 删除
 delete from app where applicationId = ?
 
 更新一条数据
 update app set name = ? where name = ?

 
 查找整张表
 select * from app
 
 */


@end

这些简单的增删改，足够我们日常使用了

再补充一点

• 一个数据库可以创建多个表格
  下面在数据库/Documents/appa.db中再创建一个