I have a scenario in which I am not sure about what to do.
I have a website where a user can update their status. I am allowing the use of hash tags so a possible user post might look like:
Went for a great hike today!! #hiking
Now, I intend to store the post in a table appropriately named "POSTS" which is structured like this:
post_id | user_id | text | date
Now, when a user submits the form which holds the post text I run a script to create an array to get all of the hash tag terms the user used and then store them in an array.
So then I can loop through that array and insert the tags into the aptly named "TAGS" table. Now the structure of this table is this:
tag_id | post_id | user_id | tag
The only problem with this is that I do not know the post_id of the post until after I insert the data into the "POSTS" table (post_id is the primary key and is auto increment).
Now, I was thinking I could just SELECT the last row of data from the "POSTS" table for that user (after I insert the post), and then in turn use the returned post_id for my query that inserts the tag data into the "TAGS" table. This seems like not the best way? My question is:
Is this the best solution or is there a better way to go about this scenario?
I am brand new to Stack Overflow, so don't please down vote me. Comment and tell me what I am doing wrong and I will learn and ask better questions.
Thanks
You can get last insterted ID very simply:
mysql_insert_id() if you don't use PDO or using function lastInsertId() if you do.
Have a new column in both tables - unique_id - which holds a string you generate in code before querying the database. That way you have an id to tie posts and tags together before submission. I use this method all the time for similar applications.
Only issue is uniqueness, but there a variety of ways to generate unique ids (I normally use a mixture of timestamps and hashing).
This sort of depends on which version of mysql you're using and how you want to organize your code.
Option 1. Do exactly what you've said. PHP would contain the code to manage the database and how data is stored into the database. The only drawback that I see in what you've outlined is if there's an issue with dealing with the hashtags, then possibly you would have a post that is inserted to the database, but the hash part did not successfully complete. For certain applications (like a bank account), this may not be acceptable and this is what database transactions are for.
Option 2. Another way to handle this would be to write a mysql stored procedure that does both the insert and handling the hash tags. The stored procedure could also wrap the whole thing in a transaction so that your database is consistent. Note that this requires a version of mysql that supports stored procedures. The bad side of doing this is that you would have to write in mysql, which is different from PHP.
Both mysql and PHP can handle this application logic/datastore logic. It is a matter of how you want to organize the code. I would prefer keeping the layers distinct. Even if you are to do this in PHP, at least have a separate class that deals with the database and not do anything else. When your code gets bigger, having a separate class or module or namespace that manages these types of code really makes them easier to change and to test.
Related
I need to insert data into DB in two language, and I am having a bit of a dilemma (data needs to exist in both languages). Is it better to make user insert data in both language at once, or is it better for the user to first insert in one language and then to insert in the second one? And if the latter is better how is the most efficient way to do this? How can I present all articles that are not inserted in both language?
DB structure for the articles:
Common table for all article (same data):
**article -> id_article | image | date_created | category_id | subcategory_id**
Table where data is different:
article_info -> article_id | name | text | lang_id
If the data must exist in both languages - i.e., the application assumes that if an item exists in one language, than it must exist in the other - then you should design your application so that the user must add them both at once.
When you perform the database writes, you should also be using transactions. This will ensure that either all of your writes succeed, or none of them do. It prevents the database from being left in an indeterminate state with a record for one language but not the other.
Have a look at this CodeIgniter manual page on transactions to get an idea on how they work.
You can also use the insert_batch method in the database class to insert both records at once. I don't know how it works with all database drivers, but the mysqli driver will generate a single query when you use insert_batch, so the entire insert will succeed or the entire insert will fail, similar to what happens with transactions. That said, I would still wrap the call to insert_batch in a transaction block just to be a bit paranoid and future-proof.
I have a problem how to store some data in mysql.
I have website which when link is pressed pass some data to php file which read this data with get and write in database(mysql). I'm passing campaign_id and unknown number of parameters.
http://domain.com/somefile.php?campaignid=1¶meter1=sometext1¶meter2=sometext2¶meter3=sometext3,....etc..
I don't know actual number of parameters because user make them in some sort of cms. The problem I'm facing is how to store them in database. I was thinking to make it like this below but i'm not sure if it's the right and the most effective way:
Combinations Table
-combination_id (Primary key and auto increment)
-campaign_id
-parameter1
-parameter2
-parameter3
-parameter4
-parameter5
-parameter6
-parameter7
-parameter8
-parameter9
-parameter10
In this example I assume that user will not add/use more than 10 parameters(which I think is lame, but I can't get better solution)
Also if I use this design I assume I need to check in this file where is get them from passing and write to database, if each parameter exist(if it was passed).
You have to normalize your schema.
Assume the following tables:
Entity: id, campaign_id, other fields.
Parameter: id, entityId, parameterValue.
This is a Many-to-One relation.
What About storing all the parameters as json in one table row?
You could try something like this:
combination_id (primary key auto increment)
campaign_id ( indexed / foreign key / can't be unique!)
param_name
param_value
You'd have to create an entry for every parameter you're getting, but you could theoretically add a thousand parameters or more.
Might not be the fastest method though and can be a bit hard to work with.
I think this is the kind of data nosql databases are made for... At least, trying to force it into a sql database always ends up as some kind of kludge. (been there done it...)
as far as I can see, you have three different ways of storing it:
As you proposed. Probably the easiest way to handle it and also probably the most efficient. But, at the moment you get 11 parameters you are in for major problems...
Make a parameter table - parameter_id, - campaign_id parameter (possible parameter name if it matters) - this gives you total flexibility - but everything else, ecept for searching for single values gets more difficult,
Combine the parameters and store them all in a text or varchar field. This is probably even more efficient than 1, except for searching for single parameter values.
And if I may add
Use a database system with an array type, eg postgresql
If you don't know the actual number of parameters that will come through url, there is a best option to store the infinite number of values for a campaign_id.
For that you can create multiple rows in the table. Like,
insert into table_name values(<campaign_id>,<parameter1>,<sometext>)
insert into table_name values(<campaign_id>,<parameter2>,<sometext>)
insert into table_name values(<campaign_id>,<parameter3>,<sometext>)
insert into table_name values(<campaign_id>,<parameter4>,<sometext>)
Assuming the campaign_id is unique in url.
I'm trying to figure out how to best keep revision/history information on revisions to multiple rows of data, in case for some reason we need to revert to that data.
This is the general sort of layout:
item
---------------
id
title
etc...
region
---------------
id
title
etc...
release_type
-----------------
id
title
etc...
items_released_dates_data
---------------------
item_id
region_id
release_type_id (these three form the primary key)
date
So you can have one release date per item + region_id + release_type and we basically only track the date (For the purposes of this question the 'date' could be a number, a string, or whatever. I'm certain to run into this issue again)
Changes are submitted in bulk, when new data is added everything in items_released_dates_data where item_id=your_id is first deleted then an insert statement adds the new values (perhaps this isn't the best way to do this?)
My thought was to create a table like:
items_release_dates_data_history
-------------------------------------
item_id
timestamp
description
raw_data
Making description a short summary of what was updated, and including the data in some format like json or xml or something that could be quickly decoded on the client side to give the user a review of the changes and a choice to revise to a given version. Then every entry to items_released_dates_data also requires an entry to items_released_dates_data_history (doesn't sound like a question does it? :| )
I've read something about mysql triggers that would be helpful here, but quite frankly I don't know a thing about them so I'm working with what I understand.
My question is, am I following the right path to version this stuff, and is there any advice/best practices anyone can give me on how to improve this method?
I second Alex Miller's comment. Everything you write make sense so far.
I'd strongly recommend looking into triggers though, despite your reservations. They're fairly easy to grasp, and make for a very powerful tool in such scenarios. Using triggers you can store a copy of the row into a separate table each time a record is updated (or deleted). If you want to go all fancy you can, within the trigger, compare the incoming data to the existing data, and write only what has changed.
Also consider the Archive storage engine instead of MyISAM or InnoDB for these kinds of tables - they're made for this kind of job.
Also, the search phrase you're probably looking for is "audit trail".
I'd say that you're definitely on the right track. Although, you may want to store the region ID in the history so you can check release history based on a region rather than just by entire items.
As for the delete+insert, that's fine as long as you don't end up with too much traffic, as those are both locking actions. There is a lot of time used when inserting or deleting a row to update the index. If you're using a MyISAM table, it's also going to halt all reads on the table until those actions complete. Update will as well, but for a much shorter time. InnoDB will only lock the row, so that's not really a concern.
I have around 150 different databases, with dozens of tables each on one of my servers. I am looking to see which database contains a specific person's name. Right now, i'm using phpmyadmin to search each database indvidually, but I would really like to be able to search all databases and all tables at once. Is this possible? How would I go about doing this?
A solution would be to use the information_schema database, to list all database, all tables, all fields, and loop over all that...
There is this script that could help for at least some part of the work : anywhereindb (quoting) :
This code is search all the tables and
all the rows and columns in a MYSQL
Database. The code is written in PHP.
For faster result, we are only
searching in the varchar field.
But, as Harmen noted, this only works with one database -- which means you'd have to wrap something arround it, to loop over each database on your server.
For more informations about that, take a look at Chapter 19. INFORMATION_SCHEMA Tables ; especially, the SCHEMATA table, which contains the name of all databases on the server.
Here's another solution, based on a stored procedure -- which means less client/server calls, which might make it faster : http://kedar.nitty-witty.com/miscpages/mysql-search-through-all-database-tables-columns-stored-procedure.php
The right way to go about it would be to NORMALIZE your data in the first place!!!
You say name - but most people have at least 2 names (a surname and a forename) are these split up or in the same field? If they are in the same field, then what order do they appear in? how are they capitalized?
The most efficient way to try to identify where the data might be would be to write a program in C which sifts the raw data files (while the DBMS is shut down) looking for the data - but that will only tell you what table they apppear in.
Failing that you need to write some PHP which iterates through each database ('SHOW databases' works much like a select statement), then iterates through each table in the database, then generates a SELECT statement filtering on each CHAR or VARCHAR column large enough to hold the name you are looking for (try running 'DESC $table').
Good luck.
C.
The best answer probably depends on how often you want to do this. If it is ad-hoc once a week type stuff then the above answers are good.
If you want to do this kind of search once a second, maybe create a "data warehouse" database that contains just the table:columns you want to search (heavily indexed, with a reference back to the source database if that is needed) populated by cron job or by stored procedures driven by changes in the 150 databases...
I'm working on a basic php/mysql CMS and have a few questions regarding performance.
When viewing a blog page (or other sortable data) from the front-end, I want to allow a simple 'sort' variable to be added to the querystring, allowing posts to be sorted by any column. Obviously I can't accept anything from the querystring, and need to make sure the column exists on the table.
At the moment I'm using
SHOW TABLES;
to get a list of all of the tables in the database, then looping the array of table names and performing
SHOW COLUMNS;
on each.
My worry is that my CMS might take a performance hit here. I thought about using a static array of the table names but need to keep this flexible as I'm implementing a plugin system.
Does anybody have any suggestions on how I can keep this more concise?
Thankyou
If you using mysql 5+ then you'll find database information_schema usefull for your task. In this database you can access information of tables, columns, references by simple SQL queries. For example you can find if there is specific column at the table:
SELECT count(*) from COLUMNS
WHERE
TABLE_SCHEMA='your_database_name' AND
TABLE_NAME='your_table' AND
COLUMN_NAME='your_column';
Here is list of tables with specific column exists:
SELECT TABLE_SCHEMA, TABLE_NAME from COLUMNS WHERE COLUMN_NAME='your_column';
Since you're currently hitting the db twice before you do your actual query, you might want to consider just wrapping the actual query in a try{} block. Then if the query works you've only done one operation instead of 3. And if the query fails, you've still only wasted one query instead of potentially two.
The important caveat (as usual!) is that any user input be cleaned before doing this.
You could query the table up front and store the columns in a cache layer (i.e. memcache or APC). You could then set the expire time on the file to infinite and only delete and re-create the cache file when a plugin has been newly added, updated, etc.
I guess the best bet is to put all that stuff ur getting from Show tables etc in a file already and just include it, instead of running that every time. Or implement some sort of caching if the project is still in development and u think the fields will change.