What would be the best way to create a filter feature in PHP so the user can select which records they want displayed in a table.
For example, a database of addresses. I want to add a feature so the user can select which county they want displayed in a table (A filter feature).
I plan to just run a for each to loop through each of the rows and add the county to a checkbox group so then the user can check which of the counties they want to be displayed then I can base my MySQL query on that but I figures it would take time especially since I'd be having 5000 or more records.
What would be the most convenient way to achieve this and is there a command or a feature in PHP to get all the unique values in a column so I can list them in the filter box?
Focus more on the SQL aspect of the problem. Try:
SELECT DISTINCT column_name FROM table_name;
Also, you could make your database such that the countries are foreign keys to another COUNTRY table. this will reduce a huge amount of redundancy as the database is not filled with repeated mentions of same names.
NOTE: Never retrieve all the entries from the database and run for each loops, try to retrieve as few rows as possible from the database.
Related
I have this problem where I want to create a data page where you can see how you've progressed in losing weight. I start by collecting their weight, but in order for me to actually do stuff with the data, I need multiple values.
For example - Below is a picture of my colums, where vaegtUsers and hoejdeUsers is the weight and height, however, I can't really figure out how to store multiple weight values in one single column? Is there some way to get around this? I've done a bit of research and almost all say it's not possible. Should I just add a new column for each "new" weight ID or keep creating tables for each individual user? Or should I do something completely else?
Since it appears a single user may have multiple weights at different times, you have a one to n relationships. You should create a second table (for instance, Measure) which refers to your User table.
This table could contain columns such as ID, UserId, MeasureDate, and weight.
You could also include height measure in this table if your users are not yet fully grown, and therefore susceptible to have varying height at different points in time. Otherwise, height could be stored inside user table.
On a side note, i would advise you to check database normalization for relational databases.
I have a MySQL database that is becoming really large. I can feel the site becoming slower because of this.
Now, on a lot of pages I only need a certain part of the data. For example, I store information about users every 5 minutes for history purposes. But on one page I only need the information that is the newest (not the whole history of data). I achieve this by a simple MAX(date) in my query.
Now I'm wondering if it wouldn't be better to make a separate table that just stores the latest data so that the query doesn't have to search for the latest data from a specific user between millions of rows but instead just has a table with only the latest data from every user.
The con here would be that I have to run 2 queries to insert the latest history in my database every 5 minutes, i.e. insert the new data in the history table and update the data in the latest history table.
The pro would be that MySQL has a lot less data to go through.
What are common ways to handle this kind of issue?
There are a number of ways to handle slow queries in large tables. The three most basic ways are:
1: Use indexes, and use them correctly. It is important to avoid table scans on large tables; this is almost always your most significant performance hit with single queries.
For example, if you're querying something like: select max(active_date) from activity where user_id=?, then create an index on the activity table for the user_id column. You can have multiple columns in an index, and multiple indexes on a table.
CREATE INDEX idx_user ON activity (user_id)
2: Use summary/"cache" tables. This is what you have suggested. In your case, you could apply an insert trigger to your activity table, which will update the your summary table whenever a new row gets inserted. This will mean that you won't need your code to execute two queries. For example:
CREATE TRIGGER update_summary
AFTER INSERT ON activity
FOR EACH ROW
UPDATE activity_summary SET last_active_date=new.active_date WHERE user_id=new.user_id
You can change that to check if a row exists for the user already and do an insert if it is their first activity. Or you can insert a row into the summary table when a user registers...Or whatever.
3: Review the query! Use MySQL's EXPLAIN command to grab a query plan to see what the optimizer does with your query. Use it to ensure that the optimizer is avoiding table scans on large tables (and either create or force an index if necesary).
I have two MySQL databases. I would like to data from one database to another. Both have the same structure and entries except that one database has same IDs for different items within the same tables. I don't want to replace the data from the old to the new database. If IDs are there, I would like the new database to skip it. If it's a duplication, I would like a new ID to be generated.
I'd like to use phpmyadmin for this but have no idea if this is even possible.
0.) Make backup of both tables
PHPMYADMIN will be sufficient for your request.
First you need to ensure there is no duplicating id's or primary keys.
Assuming two tables testtable1 and testtable2 have columns testtable_id, name
1.) firstly you would make query on second table
UPDATE testtable2 SET testtable2.testtable_id = testtable2.testtable_id + (SELECT MAX( testtable1.testtable_id ) FROM testtable1);
2.) Than, again in testtable2, there is tool Copy table to (database.table): under Operations menu, set DB name and testtable1 name (db name should be already set), select Data only radio button option and click Go. 3.) Now, you have all data from both tables in testtable1.
Edit. Firstly I thought it is matter of two tables in same database. But nevertheless you can use step two for rest of the tables too. Just set correct DB and table name in step two. Also, before that, set query so expecting ID to be higher than MAX ID of table you want to extend. You can hard code parenthesis part with exact number of MAX ID first DB corresponding table.
Trying to store the terms of a search. I've created a table "Searches" which stores each of the search terms in it's own field (bedrooms, baths, etc). So each row will contain one search.
On the advanced search form, users can select multiple search terms for a single field using an option select. I thought it would be wise to store each of these terms in a unique row of a related table for easy statistics reporting. I thought this way I could quickly report how many times a term is searched for. I also need to have the ability to save and regenerate the search query.
However if none of the terms searched are in the main table, I still need to generate a unique id to link it to the related table. So I would need to insert a blank row to generate the foreign key which I'm reluctant to do.
Is there a better way? I could store the multiple search terms questions in the primary table comma separated but it seems like it would be more difficult to pull them back out and count for statistics etc.
Why do you need to insert a blank row? You don't need to persist any of the records until the time comes to persist all of the records, right?
So as I understand it, your table layout is something like:
Table1
--------
ID
etc.
Table2
--------
ID
Table1ID
etc.
If that's the case, then the order of operations for inserting the data would look like this:
Begin Transaction
Insert into Table1
Get the last inserted ID
Insert into Table2
Commit Transaction
Assuming I understand your UX correctly, this would all happen when the user submits the form.
if i understand you,
it seems like you should have two tables:
search_term
-----------------
term_id
term
and
search
-----------------
search_id
term_id
then you can query search for all the terms and issue the SELECT statement.
whose structures are identical and which even have the same id's, now one of these databases collects information from a live feed, what i want to do is find a way to add just the new records to the second database so that the information can then be reviewed and managed, without disturbing the first database.
Is there an easy way to do this?
Depending on the size of your tables and whether or not you want to be selective about what you move from table1 to table2:
INSERT INTO table2 (field1,field2,field3)
SELECT field1,field2,field3 FROM table1
Should to the trick, add orders and where clauses etc as required!