Operation of database using FMDB in iOS (1)

For the operation of the database FMDB in iOS, it is recommended to write the method as a singleton. The following are some basic operations on the database

1. Create a table in the local database

  // Get Documents directory path NSString *documentsPath = [ NSSearchPathForDirectoriesInDomains ( NSDocumentDirectory , NSUserDomainMask , YES ) lastObject ]; // File path NSString *filePath = [documentsPath stringByAppendingPathComponent : @"model.sqlite" ]; // Instantiate FMDataBase object _db = [ FMDatabase databaseWithPath :filePath];
   
   
   
   
   

    [ _db open ];
    FMResultSet *rs = [ _db executeQuery : @"select count(*) as 'count' from sqlite_master where type ='table' and name = ?" , @"numberData" ];
    while ([rs next ])
    {
        NSInteger count = [rs intForColumn : @"count" ];
        NSLog ( @"isTableOK %ld" , ( long )count);
        if ( 0 == count){ // 不存在 break;         } else{//
           

        存在
            [ _db close ];
            return ;
        }
    }
    // 初始化数据表 NSString *personSql = @"CREATE TABLE 'numberData' ('numID' INTEGER PRIMARY KEY AUTOINCREMENT  NOT NULL ,'number' VARCHAR(255),'dateStr' VARCHAR(255),'qiNum' VARCHAR(255)) ";     [_dbexecuteUpdate:personSql];     [_dbclose];
   

   

Second, increase

 [_dbopen];
    NSNumber *maxID = @(0);
    FMResultSet *res = [_dbexecuteQuery:@"SELECT * FROM numberData "];
    //获取数据库中最大的ID while ([res next]) { if ([maxID integerValue] < [[resstringForColumn:@"numID"]integerValue]) {             maxID = @([[resstringForColumn:@"numID"]integerValue]);
   
       

        }
    }
    maxID = @([maxIDintegerValue] +1);
    [_dbexecuteUpdate:@"INSERT INTO numberData(numID,number,dateStr,qiNum)VALUES(?,?,?,?)",[NSStringstringWithFormat:@"%@",maxID],Num.number,Num.dateStr,Num.qiNum];
    [_dbclose];

三、删

       [ _db open ];
   
    if ([ _db executeUpdate : @"DELETE FROM numberData WHERE dateStr = ?" ,dateStr]) {
        [ WSProgressHUD showSuccessWithStatus : @" 删除成功！ " ];
    } else {
        [ WSProgressHUD showErrorWithStatus : @" 删除失败！ " ];
    }

    [ _db close ];

四、改

    [_dbopen];
    BOOL su = [_dbexecuteUpdate:@"UPDATE 'numberData' SET number = ?  WHERE dateStr = ? and qiNum = ?",newNum,dateStr,qiNum];
    [_dbclose];

五、查

     [ _db open ];
    NSMutableArray *dataArray = [[ NSMutableArray alloc ] init ];
    FMResultSet *res = [ _db executeQuery : @"SELECT * FROM numberData" ];
    while ([res next ]) {
        Number *num = [[ Number alloc ] init ];
        num. numID = [res stringForColumn : @"numID" ];
        num. number = [res stringForColumn : @"number" ];
        num. dateStr = [res stringForColumn : @"dateStr" ];
        num. qiNum = [res stringForColumn : @"qiNum" ];
        [dataArray addObject :num];
    }
    [ _db close ];

这是个人初步接触FMDB时学的一些语句，后期对这些东西进行了封装，使用更加简单，具体请查看链接：

参考: