FMDB-实用实例

#import <Foundation/Foundation.h>

@interface User : NSObject

// 名字
@property (nonatomic, copy) NSString *name;

// 年龄
@property (nonatomic, assign) int age;

// 地址
@property (nonatomic, copy) NSString *address;
@end

<pre name="code" class="objc">#import "DataBaseManage.h"
#import "FMDB.h"

@interface DataBaseManage()

{
/**
数据库对象

- returns: <#return value description#>
*/
FMDatabase *_database;
}

@end

@implementation DataBaseManage

+ (NSString *) test{

NSInteger type = [DataBaseManage dataBaseManager].type;

switch (type) {
case 0:
return nil;
break;

default:
return nil;
break;
}

}

- (instancetype)init {

self = [super init];

if (self) {

// 1. 创建数据库
if (![self createDatabaseAndOpen]) {
// 创建数据库失败
return nil;
}

// 创建表
[self creatUserTable];
}
return self;
}

+ (instancetype)dataBaseManager {

static DataBaseManage *manager = nil;

//    static dispatch_once_t onceToken;
//    dispatch_once(&onceToken, ^{
//
//        manager = [[self alloc] init];
//    });
//
//    return manager;
//

@synchronized(self) {
if (!manager) {
manager = [[self alloc] init];
}
}
return manager;
}

/**
*  返回数据库路径
*/

- (NSString *)databasePath {

NSString *doucmentPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];

return [doucmentPath stringByAppendingPathComponent:@"user.db"];
}

/**
*  创建数据并打开
*/
- (BOOL)createDatabaseAndOpen {

// 初始化数据库
_database = [FMDatabase databaseWithPath:[self databasePath]];

// 打开数据: 如果数据库存在 直接打开。 否则先创建数据库然后再打开

if (![_database open]) {
NSLog(@"打开失败");
return NO;
} else {
NSLog(@"打开成功");
}

return YES;

}

/**
*  创建表
*/
- (void)creatUserTable {

NSString *sql = @"create table if not exists User( id integer primary key autoincrement,name text, age integer);";

// 除了查询是executeQusery:操作,其他都是executeUpdate操作
BOOL isOK = [_database executeUpdate:sql];

if (isOK) {
NSLog(@"创建表成功");
NSLog(@"%@",NSHomeDirectory());
} else {
NSLog(@"创建表失败");
}

}

- (BOOL)insertIntoTableWithObject:(id)object {

NSString *sql = nil;

// User
if ([object isKindOfClass:[User class]]) {
User *user = object;

sql = @"insert into User(name,age) values(?,?)";
/**
*  插入数据的时候不能有基本数据类型
(int, float, double, bool) 必须是基本类型的包装类
*/

// 执行更新
return [_database executeUpdate:sql,user.name,@(user.age)];

}
return NO;
}

/**
*  查询所有数据
*/

- (NSArray *)queryAllUserObjectsFromDatabase {

NSString *sql = @"select *from User";

// 保存所有用户信息
NSMutableArray *users = [NSMutableArray array];

// 执行查询，返回结果集

FMResultSet *results = [_database executeQuery:sql];

// 依次取出
while (results.next) {

// 根据字段名字取值
NSString *name = [results stringForColumn:@"name"];
// 根据索引取值
[results stringForColumnIndex:1];

int age = [results intForColumn:@"age"];

// 封装数据模型
User *user = [[User alloc] init];
user.name = name;
user.age = age;

// 添加到数组中
[users addObject:user];
}
return users;
}

- (NSArray *)queryObjectsFromDatabaseWithParameters:(NSDictionary *)parameters {

// select * from User where xx = xx and xx = xx

/**
*  字典遍历
for (NSString *key in 字典)
*/
NSMutableString *string = [NSMutableString string];

// 获取字典所有的key
NSArray *allkeys = parameters.allKeys;
for (int i = 0; i < parameters.count; i++) {

// key
NSString *key = allkeys[i];
if (i == parameters.count - 1) {
[string appendFormat:@"%@==%@",key,parameters[key]];
} else {
[string appendFormat:@"%@=%@ and",key,parameters[key]];
}

}
return nil;

}

/**
*  更新数据
*/
- (BOOL)updateUserObjectWithParameters:(NSDictionary *)parameters {

// update User set name = "xxx" where id = "xxx"

return NO;
}

/**
*  把名字删除
*/
- (void)delectUserObjectFromDatabaseWithName:(NSString *)name {

NSString *sql = @"delete from User where name = ?";

[_database executeUpdate:sql,name];
}

/**
*  数据库关闭
*/
- (BOOL)close {

return [_database close];
}

@end