This one might be a bit complicated. I searched for similar questions and found nothing that seemed relevant.
Let me start by establishing my database structure.
I have several tables, but the relevant ones are as follows:
Right now I have the decklist stored as a string of cardid delimited by a comma. I realize this is inefficient and when I get around to improving my code I will make a new table tcg_card_in_deck that has relationid, cardid, deckid. For now my code assumes a decklist string.
I'm building a function to allow purchases of a deck. In order to give them the actual cards, I have the following query (generated with the PHP it will actually be about 50 entries):
$db->query_write("INSERT INTO
`tcg_card`
(masterid, userid, foil)
VALUES
('159', '15', '0'),
('209', '15', '0'),
('209', '15', '0'),
('318', '15', '0')");
This part is easy. My issue now is making sure the cards that have just been added can have their ids grabbed and put together in an array (to enter in as a string currently, and as entries into the separate table once the code is updated). If it was one entry I could use LAST_INSERT_ID(). If I did 50 separate insert queries I could grab the id on each iteration and add them into the array. But because it's all done with one query, I don't know how to effectively find the correct cards to put in the decklist. I suppose I could add a dateline field to the cards table to specify date acquired, but that seems sloppy and it may produce flawed results if a user gets cards from a trade or a booster pack in a similar timeframe.
Any advice would be appreciated!
Change tcg_card by removing cardid, and make masterid and userid a compound key. Then, add a row called quantity. Since you cannot distinguish between two copies of a card in any meaningful way (except for being foils, which you could handle with this schema), there is no need for every card to get its own ID.
Presumably you aren't entering new tcg_master rows dynamically, so you don't have to worry about pulling their IDs back out.
Reading comments on this question I thought of a very simple and easy solution:
Get all inserted IDs when inserting multiple rows using a single query
I already track booster pack purchases with a table tcg_history. This table can also track other types of purchases, such as a starter deck.
I simply need to add a field on the tcg_card table that references a tcg_history.recordid, then I will be able to select all cards that are from that purchase.
Related
Hi, so I have this database project I'm working on that involves transcribing archival sources to make them more accessible.
I'm revamping the database structure, so I can make the depiction of the archival data more accurate to the manuscript sources. As part of that, I have this new table, which has both the labels/titles for columns of data in the documents, plus a "used"field which acts both as a flag for if the field is used, and also for what position it should be in left to right (As the order changes sometimes).
I'm wondering if there's a way to pair the columns together so I can do a query that - when asking for a single row to be returned= sorts the "used" functions numerically (returning all the ones that aren't -1), and also returns all the "label" fields also sorted into the same order (eg if guns_used is 2, and men_used is 1 and ship_name_position is 0, the query will put them in the correct order and also return guns_label, men_label and shipname_label in the correct order).
I'm also working with/around wordpress, so I have the contents of the whole wpdb thing available to me too.
I'm hoping to be able to "pair" the fields in some way so that if I order one set, the other gets ordered as well.
Edit:
I really would prefer to find a way to do this in a query but until I find a way to do that I'm going to
a)Select the entire row that I need
b)Have a long series of if statements- one for each pair of _label/_used fields- and assigning the values I want to the position in the array indicated by the value of the _used field.
I'm new to sql & php and unsure about how to proceed in this situation:
I created a mysql database with two tables.
One is just a list of users with their data, each having a unique id.
The second one awards certain amounts of points to users, with relevant columns being the user id and the amount of awarded points. This table is supposed to get new entries regularly and there's no limit to how many times a single user can appear in it.
On my php page I now want to display a list of users sorted by their point total.
My first approach was creating a "points_total" column in the user table, intending to run some kind of query that would calculate and update the correct total for each user every time new entries are added to the other table. To retrieve the data I could then use a very simple query and even use sql's sort features.
However, while it's easy to update the total for a specific user with the sum where function, I don't see a way to do that for the whole user table. After all, plain sql doesn't offer the ability to iterate over each row of a table, or am I missing a different way?
I could probably do the update by going over the table in php, but then again, I'm not sure if that is even a good approach in the first place, because in a way storing the point data twice (the total in one table and then the point breakdown with some additional information in a different table) seems redundant.
A different option would be forgoing the extra column, and instead calculating the sums everytime the php page is accessed, then doing the sorting stuff with php. However, I suppose this would be much slower than having the data ready in the database, which could be a problem if the tables have a lot of entries?
I'm a bit lost here so any advice would be appreciated.
To get the total points awarded, you could use a query similar to this:
SELECT
`user_name`,
`user_id`,
SUM(`points`.`points_award`) as `points`,
COUNT(`points`.`points_award`) as `numberOfAwards`
FROM `users`
JOIN `points`
ON `users`.`user_id` = `points`.`user_id`
GROUP BY `users`.`user_id`
ORDER BY `users`.`user_name` // or whatever users column you want.
I'm building an eCommerce site with Codeigniter which will allow users to register, buy products and then track the orders.
I'm using the following in several places around the site, mainly when a user is submitting an order:
$this->db->insert_id();
Basically when a user submits an order, it will add the order to one table, and then, within the same segment of code (immediately after the insert query), add each order item to another table using the ID created when the order is inserted into the first table.
My question is: Out of the following, what does $this->db->insert_id(); do:
1) Does it get the ID that has just been inserted in (and only from) insert query just run?
2) Does it get the last inserted ID from the latest entry in the database regardless of what query its come from?
Basically I'm trying to avoid orders being mixed up, say for example if several customers were submitting orders at the same time, I don't want one customer's order items to be added to the incorrect order.
I think the answer is 1, and that there's no problem, but I wanted to be sure.
Thanks!
It gets the ID that last inserted by the last query. So what you said in #1
Just a suggestion - but another way to do this is to generate a random string - and use that to associate the cart items and order together - instead of by order id. you would still use the order id as the "order number".
this gives you the option of generating that random string when the shopping session first begins and using it to tie the cart items, shipping, billing etc together as the purchase is proceeding. so in that way you are starting the order immediately, but you haven't had to commit a space in the final order table until the transaction verifies.
Your question exposes a potential bug in the codeigniter environment. If two inserts are done in rapid succession, how do you have confidence that the ID returned from insert_id is the proper ID?
Codeigniter documentation does not answer this question
http://ellislab.com/codeigniter/user-guide/database/helpers.html
A relevant blog entry from ellis lab does not resolve the question. It concludes that the appropriate resolution is to take your chances.
http://ellislab.com/forums/viewthread/63052/
If this function is a wrapper function for mysqli_insert_id, the documentation at php.net is unclarified.
http://www.php.net/manual/en/mysqli.insert-id.php
It states the ID is from "the last query". It does not say whose last query.
Two successive inserts, and the return of a wrong ID will compromise the integrity of your data. The way to be sure is lock the database.
$this->db->query('LOCK TABLE (your table name) WRITE');
$this->db->insert('(your table name');
$int_id = $this->db->insert_id();
$this->db->query('UNLOCK TABLES');
This has a negative impact on execution time, but depending on your server's capacity is likely preferable to data corruption.
I've got a problem that I just can't seem to find the answer to. I've developed a very small CRM-like application in PHP that's driven by MySQL. Users of this application can import new data to the database via an uploaded CSV file. One of the issues we're working to solve right now is duplicate, or more importantly, near duplicate records. For example, if I have the following:
Record A: [1, Bob, Jones, Atlanta, GA, 30327, (404) 555-1234]
and
Record B: [2, Bobby, Jones, Atlanta, GA, 30327, Bob's Shoe Store, (404) 555-1234]
I need a way to see that these are both similar, take the record with more information (in this case record B) and remove record A.
But here's where it gets even more complicated. This must be done upon importing new data, and a function I can execute to remove duplicates from the database at any time. I have been able to put something together in PHP that gets all duplicate rows from the MySQL table and matches them up by phone number, or by using implode() on all columns in the row and then using strlen() to decide the longest record.
There has got to be a better way of doing this, and one that is more accurate.
Do any of you have any brilliant suggestions that I may be able to implement or build on? It's obvious that when importing new data I'll need to open their CSV file into an array or temporary MySQL table, do the duplicate/similar search, then recompile the CSV file or add everything from the temporary table to the main table. I think. :)
I'm hoping that some of you can point out something that I may be missing that can scale somewhat decently and that's somewhat accurate. I'd rather present a list of duplicates we're 'unsure' about to a user that's 5 records long, not 5,000.
Thanks in advance!
Alex
If I were you I'd give a UNIQUE key to name, surname and phone number since in theory if all these three are equal then it means that it is a duplicate. I am thinking so because a phone number can have only one owner. Anyways, you should find a combination of 2-3 or maybe 4 columns and assign them a unique key. Once you have such a structure, run something like this:
// assuming that you have defined something like the following in your CREATE TABLE:
UNIQUE(phone, name, surname)
// then you should perform something like:
INSERT INTO your_table (phone, name, surname) VALUES ($val1, $val2, $val3)
ON DUPLICATE KEY UPDATE phone = IFNULL($val1, phone),
name = IFNULL($val2, name),
surname = IFNULL($val3, surname);
So basically, if the inserted value is a duplicate, this code will update the row, rather than inserting a new one. The IFNULL function performs a check to see whether the first expression is null or not. If it is null, then it picks the second expression, which in this case is the column value that already exists in your table. Hence, it will update your row with as much as information possible.
I don't think there're brilliant solutions. You need to determine priority of your data fields you can rely on for detecting similarity, for example phone, some kind of IDs, of some uniform address or official name.
You can save some cleaned up values (reduced to the same format like only digits in phones, concatenated full address) along with row which you would be able to use for similarity search when adding records.
Then you need to decide on data completeness in any case to update existing rows with more complete fields, or delete old and add new row.
Don't know any ready solutions for such a variable task and doubt they exist.
I have a field in a table recipes that has been inserted using mysql_real_escape_string, I want to count the number of line breaks in that field and order the records using this number.
p.s. the field is called Ingredients.
Thanks everyone
This would do it:
SELECT *, LENGTH(Ingredients) - LENGTH(REPLACE(Ingredients, '\n', '')) as Count
FROM Recipes
ORDER BY Count DESC
The way I am getting the amount of linebreaks is a bit of a hack, however, and I don't think there's a better way. I would recommend keeping a column that has the amount of linebreaks if performance is a huge issue. For medium-sized data sets, though, I think the above should be fine.
If you wanted to have a cache column as described above, you would do:
UPDATE
Recipes
SET
IngredientAmount = LENGTH(Ingredients) - LENGTH(REPLACE(Ingredients, '\n', ''))
After that, whenever you are updating/inserting a new row, you could calculate the amounts (probably with PHP) and fill in this column before-hand. Or, if you're into that sort of thing, try out triggers.
I'm assuming a lot here, but from what I'm reading in your post, you could change your database structure a little bit, and both solve this problem and open your dataset up to more interesting uses.
If you separate ingredients into its own table, and use a linking table to index which ingredients occur in which recipes, it'll be much easier to be creative with data manipulation. It becomes easier to count ingredients per recipe, to find similarities in recipes, to search for recipes containing sets of ingredients, etc. also your data would be more normalized and smaller. (storing one global list of all ingredients vs. storing a set for each recipe)
If you're using a single text entry field to enter ingredients for a recipe now, you could do something like break up that input by lines and use each line as an ingredient when saving to the database. You can use something like PHP's built-in levenshtein() or similar_text() functions to deal with misspelled ingredient names and keep the data as normalized as possbile without having to hand-groom your [users'] data entry too much.
This is just a suggestion, take it as you like.
You're going a bit beyond the capabilities and intent of SQL here. You could write a stored procedure to scan the string and return the number and then use this in your query.
However, I think you should revisit the design of whatever is inserting the Ingredients so that you avoid searching strings in of every row whenever you do this query. Add a 'num_linebreaks' column, calculate the number of line breaks and set this column when you're adding the Indgredients.
If you've no control over the app that's doing the insertion, then you could use a stored procedure to update num_linebreaks based on a trigger.
Got it thanks, the php code looks like:
$check = explode("\r\n", $_POST['ingredients']);
$lines = count($check);
So how could I update all the information in the table so Ingred_count based on field Ingredients in one fellow swoop for previous records?