This is a bit of a difficult problem for me to word, and I may be going about it in the completely wrong way.
I'm storing a set of options in a database, where each option is its own column. The user can change the number of options, however, so I need a way of allowing PHP to always select all the options.
Let's say I have these columns: options_dialog_1, options_dialog_2, options_dialog_3, options_dialog_4
There could be a varying number of these dialog option columns, eg, another called options_dialog_5 could be added.
How do I select all the dialog option columns, based on their column name format?
I think you have a database design problem here; repeating columns like that always leads to trouble in the end. I think you need two tables, one for the user and one for the options defined something like this...
USERS
id
name
OPTIONS
id
user_id
option_dialogue_number
option_dialogue_value
That turns the columns into rows, which are rather easier to get at.
Brian's answer will really, really pay you off in longer period. But if you need something quick & ugly, you can check out the "metadata dictionary" (tables that store information about all other tables, columns etc). You could get list of columns from it with first query and use it to build the second one.
SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='mytable' AND COLUMN_NAME LIKE 'options_dialog%'
Visit the manual on INFORMATION_SCHEMA for more goodies.
I am not sure I understand the problem. Are you looking for
SELECT * FROM options_table
Something like (faux SQL - wont work)
SELECT ( SELECT column_names where column_name LIKE 'options_dialog%' )
FROM options_table
sounds not feasible to me (though I am sure it's possible somehow). If you need this, either consider refactoring the database design or maybe use a bitmask to store the selected options in a single column.
Related
Which of below query will be better to use if table has single column? Please also provide technical justification.
select * from table
or
select `name` from table
Speed/execution be the same. Just because of future table changes (and clarity of the message) you should use second option.
* is just placeholder for all; though there is no difference, because engine treats it like name in that case, but if some day you change table rows (add something, for example surname) it would be best choice, to use just name in select statement due to avoid future source-code changes.
I have a trivial question. Im using PHP+MySQL managing a huge DB
I want to search in a entire table a keyword I write in a input.
The problem is that the main table have +100 columns, so I had to write the php query manually
[...]
$sql="select *
from db
where ID LIKE '%".$q."%' or USER_ID LIKE '%".$q."%' or Phone_ID LIKE '%".$q."%' or
Fax_ID LIKE '%".$q."%' or email_ID LIKE '%".$q."%' or [...]
And this is a chaos when I modify a column, or add/remove...
Exist any other way to make this search? If not, I tought about create a separate PHP function, that obtains all column header names, and create an auto-fill function inside.
I tried to look for info with no success
https://stackoverflow.com/search?q=search+entire+table
Unfortunately there isnt any simple way to do this.
One option is to select all columns in table, fetch them as array and iterate over them and build your WHERE clause.
select column_name from information_schema.columns
where table_name = 'TableName'
This will make whole script slower, if you want to go this way i would recommend you to use some caching.
You could get the column info for the 'main table' using info from the information schema. Here are some methods for using MySQL. Here is how to do it using PHP.
You can do a SHOW COLUMNS on the table, then loop over the Field to get all the column names in the table, at least that way you don't have a hand-coded mess to deal with.
Well I'm having a problem mainly caused by bad structure in database. I'm coding this for a company whose code is quite messy and the table is very large so I don't think it's an option to fix the structure.
Anyway, my issue is that I'm trying to somehow group a value that won't be alone in the string...
They are storing values separated with commas... So it would be like
field: "category" value: 'var1, var2, var3'
And I will search using this query:
SELECT name, category
FROM companies
WHERE (MATCH(name, category) AGAINST ('$search' IN BOOLEAN MODE)
OR category LIKE '$search%')
It would match with for example var2 (it's not limited to 3 variables though, can be solo or many more) and I'd split it manually in PHP, no problem. Although I will not get enough matches, I want e.g. 10 matches by different searches. To be more specific I'm making an autosuggest feature, which means I will for example want to match "moto%" with motorbike, motor alone or whatever but I keep getting the same values, like there'd be a couple of 100 of results that contains "motorbike" and I don't know how to filter them, as I'm not able to use GROUP BY due to bad db structure...
I found this: T-SQL - GROUP BY with LIKE - is this possible?
It SEEMED as something that would be a solution, but as far as I've tried I could not get it work with what I wanted.
So I'm wondering which solutions there are... If there are ABSOLUTELY no way of working this around I might probably have to fix the db structure (but this really has to be the last option)
Start taking steps to make database structure proper. Make an extra table and fill it with split values.
Then you can use proper queries to select the data you need. Both you and next developer will have less troubles with this project in the future, not mentioning queries speed gain.
I am not sure why i cannot write a comment, but maybe you can try this:
SELECT name, category FROM companies WHERE category LIKE '$search%' or LOCATE('search', category)>0;
That would look if in category appears any of your 'search' value.
I would have to agree that you should make the database right. It'll save you much trouble and time later. However, using SELECT DISTINCT may fix your immediate issue.
Imagine it like this. There is a field in my database called flags in which are added or removed data like this:
UPDATE people SET flags=flags|16 WHERE ....
UPDATE people SET flags=flags|128 WHERE ....
UPDATE people SET flags=flags&~16 WHERE ....
UPDATE people SET flags=flags&~128 WHERE ....
For instance this field can have value like 65536 or more or less. My question is - How to get specific flag from this field using PHP code? I mean something like this:
SELECT * FROM people WHERE flags=16;
But the result will return all people with not just number 16 in field but it will return people with flag 65536, people with 16 but not people with 2 or 1. Which SELECT query should I use here in my php code or maybe some specific PHP integrated functions? Thank you.
Assuming flags is a bitfield and you want to select rows where bit #4 (10000) is set
SELECT * FROM people WHERE flags & 16;
This is not ideal though as you're losing out on all that referential goodness that DBs are good for.
What you should have is two new tables; flags and people_flags. The former contains all the flags (id and name columns should be sufficient). The latter contains flag_id and people_id columns, creating a many-to-many relationship (see junction table).
The logic is not correct though. You cant have just one flag that contains 16 as its not unique.
Lets say you have DB with this rows
name:Jhon tel:012345 email:test#test.com flags:16
name:Mike tel:012344 email:mike#test.com flags:16
name:Sarah tel:012346 email:sarah#test.com flags:2442
to select flags 16 from this table with using Select statement you will get two rows of data you can either use Distinct or get flags to be unique
I am setting up a MySQL database with multiple tables. Several of the tables will have fields with similar names that aren't necessarily for the same purpose.
For example, there's a users table that will have a name field, a category table with a name field and so on.
I've previously seen this setup up either with or without a preface to the field name, so in the above example using user_name, cat_name etc.
As these are all in separate tables, is there any benefit to structuring the database with or without this preface? I know that when using joins and calling the data through PHP you have to add a SELECT users.name AS username... to keep the fields from overwriting each other when using mysql_fetch_array. But i'm not sure if there's any efficiencies in using one method over the other?
It depends on what your shop does or your preference. There is nothing about a prefix that will make this better. Personally I would just keep it as name since: Users.Name and Orders.Name and Products.Name all contain tuples with different object types.
At the end of the day you want to be consistent. If you prefer a cat_ and a user_ prefix just be consistent with your design and include this prefix for all object types. To me less is more.
It's really just a matter of preference. I personally prefer the approach of using just name.
One thing to watch out for though, if you're doing any SELECT * FROM ... queries (which you shouldn't be; always select fields explicitly), you may end up selecting the wrong data.
One disadvantage is if anyone is stupid enough to use natural joins (you can guess that I find this a poor practice but mysql does allow it so you need to consider if that will happen) you may end up joining on those fields with the same name by accident.