$articles = Article::paginate(10, ['*'], 'pag');
What does the second parameter [*] above do?
The first parameters is the number of resources to be displayed by page.
The third parameter is the name of the query that will appear in the URL (i.e, "pag?=3").
What about "[*]"? I've used it for a long time without knowing what it does.
Don't tell me to search in Laravel Docs because I already did this and didn't find anything useful.
2nd parameter is select() method from Illuminate\Database\Eloquent\Builder which means select * from table ... limit 15.
You can specify which columns you want select from database.
For exaple $users->paginate(10, ['id', 'name']); -> select id, name from users ... limit 10
FYI: ['*'] is not fully qualified!
If you are using join in your select, it might be a problem if the columns with the same name are present in both tables. For example uuid, etc ...
In this case you should specify table name in select: ['table_name.*'] -> select table_name.* from table_name ... limit 15
Related
I can select country and groupBy the result as following with an alias total :
Data::select('country', DB::raw('count(*) as total'))
->groupBy('country')
->get();
The above code works well.
Here I can select only country filed, But I need to select aslo name, positions field, How can I select multiple field here?
You have to use like below settings and change code.
Open config/database.php
Find strict key inside mysql connection settings
Set the value to false
Use code below like
ModelName::groupBy('country')
->selectRaw('count(*) as total, country, name, positions')
->get()
First, you need to specify what error/exception you're getting but you can add additional column by doing
DB::table('table_name')->select([DB::raw('count(*) as total'), 'name', 'positions', 'country'])
->groupBy('country')
->get());
it is also likely you get an access violation exception which requires you to change sql_mode
I have a model User that has many Orders. Orders have many products, with the pivot table order-product. I don't want to preload and iterate through the orders if at all possible.
I need to return users where
signed_date === true on User
order_date on Order is after signed_date on User
order-product shows product hasn't been paid
I am failing on number 2.
In the following code, the first query within whereHas is wrong. I don't know how to reference the signed date of the user from within the where has. If I was iterating through users in a collection I could do something like ($query) use $user, but how do I do this without preloading all the users?
return User::whereNotNull('signed_date')
->whereHas('orders', function ($query) {
$query->where('order_date', '<=', 'user.signed_date');
$query->whereHas('products', function ($q) {
$q->where('paid', false);
});
})
->get(['id','fname','lname', 'title', 'signed_date']);
I would like to use eloquent if possible. If that is not possible, I would be happy for tips in solving this problem using the query builder/sql.
The Eloquent query builder has a special function called whereColumn('a', '<=', 'b') to compare columns instead of a column against a value. Using this function instead of a normal where() is necessary because of the way the query builder builds the actual query. You need to let the query builder know that you are going to pass a column name instead of a value for proper escaping and formatting of the query string.
Anyway, it seems you can also pass column names prefixed with a table name to the function, allowing you to compare columns across tables:
$query->whereColumn('orders.order_date', '<=', 'users.signed_date')
This works because you are using whereHas() in your query. Your query basically gets translated to:
SELECT id, fname, lname, title, signed_date
FROM users
WHERE signed_date NOT NULL
AND EXISTS (
SELECT 1
FROM orders
WHERE orders.order_date <= users.signed_date
AND EXISTS (
SELECT 1
FROM products
WHERE paid = 0
)
)
It might actually be not necessary at all to use the table name together with the column name in whereColumn(). But in case you'll ever add a column named the same on another table, the query might break - so IMHO it is good practice to use the table name in custom queries.
By the way, the reason this will not work together with with('relationship') is that this function results in an additional query and you obviously cannot compare columns across queries. Imagine the following:
Order::with('user')->take(5)->get();
It will be translated into the following:
SELECT *
FROM orders
LIMIT 5
SELECT *
FROM users
WHERE id IN (?, ?, ?, ?, ?)
where the five ? will be the user_ids of the orders. If the first query returns multiple rows with the same user_id, the amount of rows fetched from the users table gets reduced of course.
Note: All the queries are only examples. Might be that the query builder builds different queries based on the database type and/or escapes them differently (i.e. column names in backticks).
Following is my query
$user = User::select(['uuid','name','about'])->with(['education','work'])->first();
this returns empty data for relationship education and work,
but if I remove select function from query I am getting data in relationship and it also returns all columns of user table which I don't want.
how can solve this problem
The problem is that relationships (with(...)) execute an additional query to get the related results. Let's say you have one to many relationship where users have many works. User::with('work')->find(1) will then execute these 2 queries:
select user where id = 1 and select works where user_id = 1.
So basically in order to be able to execute the second query (fetch relationship data) you need to include id (or whichever column you're referencing) in you select statement.
Fix:
$user = User::select(['uuid','name','about', 'id'])->with(['education','work'])->first();
Same principle in different forms applies to all relationships. For example in the inverse of hasMany which is belongsTo you would need to select the foreign key (for example user_id).
I'm using MySQL and have a table of 9 million rows and would like to quickly check if a record (id) exists or not.
Based on some research it seems the fastest way is the following sql:
SELECT EXISTS(SELECT 1 FROM table1 WHERE id = 100)
Source: Best way to test if a row exists in a MySQL table
How can I write this using Laravel's query builder?
Use selectOne method of the Connection class:
$resultObj = DB::selectOne('select exists(select 1 from your_table where id=some_id) as `exists`');
$resultObj->exists; // 0 / 1;
see here http://laravel.com/docs/4.2/queries
Scroll down to Exists Statements, you will get what you need
DB::table('users')
->whereExists(function($query)
{
$query->select(DB::raw(1))
->from('table1')
->whereRaw("id = '100'");
})
->get();
This is an old question that was already answered, but I'll post my opinion - maybe it'll help someone down the road.
As mysql documentation suggests, EXISTS will still execute provided subquery. Using EXISTS is helpful when you need to have it as a part of a bigger query. But if you just want to check from your Laravel app if record exists, Eloquent provides simpler way to do this:
DB::table('table_name')->where('field_name', 'value')->exists();
this will execute query like
select count(*) as aggregate from `table_name` where `field_name` = 'value' limit 1
// this is kinda the same as your subquery for EXISTS
and will evaluate the result and return a true/false depending if record exists.
For me this way is also cleaner then the accepted answer, because it's not using raw queries.
Update
In laravel 5 the same statement will now execute
select exists(select * from `table_name` where `field_name` = 'value')
Which is exactly, what was asked for.
my table looks like this:
If the field name contains cost or quantity for the same lineItemIds, I have to display the result as:
cost is changed from 8*1=8
(fromVal*fromVal) to 9*6=54
(toVal*toVal) for itemID 123.
any help will be appreciated.
SELECT tc.LINE_ITEM_ID ITEM_ID,
tc.FROMVAL COST_FROMVAL,
tq.FROMVAL QTY_FROMVAL,
(tc.FROMVAL*tq.FROMVAL) PROD_FROMVAL,
tc.TOVAL COST_TOVAL,
tq.TOVAL QTY_TOVAL,
(tc.TOVAL*tq.TOVAL) PROD_TOVAL,
FROM
(SELECT LINE_ITEM_ID,
FROMVAL,
TOVAL,
FROM table
WHERE FIELDNAME = 'cost') tc
JOIN (SELECT LINE_ITEM_ID,
FROMVAL,
TOVAL,
FROM table
WHERE FIELDNAME = 'quantity') tq
ON tc.LINE_ITEM_ID = tq.LINE_ITEM_ID
I would look into using product aggregate functions. You'll have to compile them yourself though, Oracle doesn't include them as system functions. http://radino.eu/2010/11/17/product-aggregate-function/
If it's just for this one case where cost or quantity are used, then you could also just use subqueries, or temporary transaction based tables.
I'd provide you with a query example, but unfortunately don't have an Oracle instance accessible presently.