カラム名一覧取得
-(NSArray*)getColumnNamesByTableName:(NSString*)tableName{
    EGODatabase*db=[self getDB];
    NSString*sql=[NSString stringWithFormat:@"pragma table_info(%@)",tableName];
    EGODatabaseResult*result=[db executeQuery:sql];
    NSMutableArray*list=[NSMutableArray arrayWithCapacity:[result count]];
    for (EGODatabaseRow*row in result) {
        [list addObject:[row stringForColumn:@"name"]];
    }
    return [NSArray arrayWithArray:list];
}