数据库更新迭代

数据库更新迭代方法一：

http://blog.youkuaiyun.com/shan1991fei/article/details/50894436

这是一种原始的写法。

数据库更新迭代方法一：

pod 'FMDB', '~> 2.6.2'
pod 'FMDBMigrationManager', '~>1.4.1'

#pragma mark - 迁移
-(void)migrations
{
    //删除列：@"alter table record drop column name"
    dispatch_sync([QueueFetcher getInstance].dbQueue, ^{
        //数据库版本升级//DBPath是要升级的数据库的地址
        NSString *docsPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
        NSString *dpPath = [docsPath stringByAppendingPathComponent:_NAME_DATABASE];
        NSLog(@"这是迁移数据库地址：==%@",dpPath);
        // [NSBundle mainBundle]是保存数据库升级文件的位置 根据自己放文件的位置定 升级文件是什么下面会说
        FMDBMigrationManager *manger = [FMDBMigrationManager managerWithDatabaseAtPath:dpPath migrationsBundle:[NSBundle mainBundle]];
        NSString *strDBM1_1 = [NSString stringWithFormat:@"alter table %@ add %@ text",TABLE_NAME,EMAIL];
        MigrationZ *migraA_1 = [[MigrationZ alloc]initWithName:@"添加邮箱email字段" andVersion:_DB_V_2 andExecuteUpdateArray:@[strDBM1_1]];
        [manger addMigration:migraA_1];
        
        NSError * error;
        BOOL result =NO;
        if (!manger.hasMigrationsTable) {
            result=[manger createMigrationsTable:&error];
        }
        
        result=[manger migrateDatabaseToVersion:UINT64_MAX progress:nil error:&error];
        if(result)
        {
            NSLog(@"迁移表成功 %@",TABLE_NAME);
        }
        else
        {
            NSLog(@"迁移表失败 %@",TABLE_NAME);
        }
        /**
         //第二种方式：
         MigrationZ * migration_1=[[MigrationZ alloc]initWithName:@"新增USer表" andVersion:1 andExecuteUpdateArray:@[@"create table User(name text,age integer)",@"create table Zhuzhu(name text,age integer)",@"create table Dong(name text,age integer)"]];
         
         MigrationZ * migration_2=[[MigrationZ alloc]initWithName:@"USer表新增字段email,Zhuzhu表新增字段email" andVersion:2 andExecuteUpdateArray:@[@"alter table User add email text",@"alter table Zhuzhu add email text"]];
         
         MigrationZ * migration_3=[[MigrationZ alloc]initWithName:@"USer表新增字段adrive" andVersion:3 andExecuteUpdateArray:@[@"alter table User add adrive text",@"alter table Dong add adrive text"]];
         
         [manager addMigration:migration_1];
         [manager addMigration:migration_2];
         [manager addMigration:migration_3];*/
        
    });
}

使用第三方：经测试使用稳定。有一个小技巧：只要有表发生改变时

“andVersion:_DB_V_2“就增加。