- Introduction
- Retrieving Results
- Selects
- Joins
- Unions
- Where Clauses
- Ordering, Grouping, Limit, & Offset
- Inserts
- Updates
- Deletes
- Pessimistic Locking
Introduction
The database query builder provides a convenient, fluent interface to creating and running database queries. It can be used to perform most database operations in your application, and works on all supported database systems.
Note: The Laravel query builder uses PDO parameter binding to protect your application against SQL injection attacks. There is no need to clean strings being passed as bindings.
Retrieving Results
Retrieving All Rows From A Table
To begin a fluent query, use the table
method on the DB
facade. The table
method returns a fluent query builder instance for the given table, allowing you to chain more constraints onto the query and then finally get the results. In this example, let‘s just get
all records from a table:
<?php
namespace App\Http\Controllers;
use DB;
use App\Http\Controllers\Controller;
class UserController extends Controller
{
/**
* Show a list of all of the application‘s users.
*
* @return Response
*/
public function index()
{
$users = DB::table(‘users‘)->get();
return view(‘user.index‘, [‘users‘ => $users]);
}
}
Like raw queries, the get
method returns an array
of results where each result is an instance of the PHP StdClass
object. You may access each column‘s value by accessing the column as a property of the object:
foreach ($users as $user) {
echo $user->name;
}
Retrieving A Single Row / Column From A Table
If you just need to retrieve a single row from the database table, you may use the first
method. This method will return a single StdClass
object:
$user = DB::table(‘users‘)->where(‘name‘, ‘John‘)->first();
echo $user->name;
If you don‘t even need an entire row, you may extract a single value from a record using the value
method. This method will return the value of the column directly:
$email = DB::table(‘users‘)->where(‘name‘, ‘John‘)->value(‘email‘);
Chunking Results From A Table
If you need to work with thousands of database records, consider using the chunk
method. This method retrieves a small "chunk" of the results at a time, and feeds each chunk into a Closure
for processing. This method is very useful for writing Artisan commands that process thousands of records. For example, let‘s work with the entire users
table in chunks of 100 records at a time:
DB::table(‘users‘)->chunk(100, function($users) {
foreach ($users as $user) {
//
}
});
You may stop further chunks from being processed by returning false
from the Closure
:
DB::table(‘users‘)->chunk(100, function($users) {
// Process the records...
return false;
});
Retrieving A List Of Column Values
If you would like to retrieve an array containing the values of a single column, you may use the lists
method. In this example, we‘ll retrieve an array of role titles:
$titles = DB::table(‘roles‘)->lists(‘title‘);
foreach ($titles as $title) {
echo $title;
}
You may also specify a custom key column for the returned array:
$roles = DB::table(‘roles‘)->lists(‘title‘, ‘name‘);
foreach ($roles as $name => $title) {
echo $title;
}
Aggregates
The query builder also provides a variety of aggregate methods, such as count
, max
, min
, avg
, and sum
. You may call any of these methods after constructing your query:
$users = DB::table(‘users‘)->count();
$price = DB::table(‘orders‘)->max(‘price‘);
Of course, you may combine these methods with other clauses to build your query:
$price = DB::table(‘orders‘)
->where(‘finalized‘, 1)
->avg(‘price‘);
Selects
Specifying A Select Clause
Of course, you may not always want to select all columns from a database table. Using the select
method, you can specify a custom select
clause for the query:
$users = DB::table(‘users‘)->select(‘name‘, ‘email as user_email‘)->get();
The distinct
method allows you to force the query to return distinct results:
$users = DB::table(‘users‘)->distinct()->get();
If you already have a query builder instance and you wish to add a column to its existing select clause, you may use the addSelect
method:
$query = DB::table(‘users‘)->select(‘name‘);
$users = $query->addSelect(‘age‘)->get();
Raw Expressions
Sometimes you may need to use a raw expression in a query. These expressions will be injected into the query as strings, so be careful not to create any SQL injection points! To create a raw expression, you may use the DB::raw
method:
$users = DB::table(‘users‘)
->select(DB::raw(‘count(*) as user_count, status‘))
->where(‘status‘, ‘<>‘, 1)
->groupBy(‘status‘)
->get();
Joins
Inner Join Statement
The query builder may also be used to write join statements. To perform a basic SQL "inner join", you may use thejoin
method on a query builder instance. The first argument passed to the join
method is the name of the table you need to join to, while the remaining arguments specify the column constraints for the join. Of course, as you can see, you can join to multiple tables in a single query:
$users = DB::table(‘users‘)
->join(‘contacts‘, ‘users.id‘, ‘=‘, ‘contacts.user_id‘)
->join(‘orders‘, ‘users.id‘, ‘=‘, ‘orders.user_id‘)
->select(‘users.*‘, ‘contacts.phone‘, ‘orders.price‘)
->get();
Left Join Statement
If you would like to perform a "left join" instead of an "inner join", use the leftJoin
method. The leftJoin
method has the same signature as the join
method:
$users = DB::table(‘users‘)
->leftJoin(‘posts‘, ‘users.id‘, ‘=‘, ‘posts.user_id‘)
->get();
Advanced Join Statements
You may also specify more advanced join clauses. To get started, pass a Closure
as the second argument into thejoin
method. The Closure
will receive a JoinClause
object which allows you to specify constraints on the join
clause:
DB::table(‘users‘)
->join(‘contacts‘, function ($join) {
$join->on(‘users.id‘, ‘=‘, ‘contacts.user_id‘)->orOn(...);
})
->get();
If you would like to use a "where" style clause on your joins, you may use the where
and orWhere
methods on a join. Instead of comparing two columns, these methods will compare the column against a value:
DB::table(‘users‘)
->join(‘contacts‘, function ($join) {
$join->on(‘users.id‘, ‘=‘, ‘contacts.user_id‘)
->where(‘contacts.user_id‘, ‘>‘, 5);
})
->get();
Unions
The query builder also provides a quick way to "union" two queries together. For example, you may create an initial query, and then use the union
method to union it with a second query:
$first = DB::table(‘users‘)
->whereNull(‘first_name‘);
$users = DB::table(‘users‘)
->whereNull(‘last_name‘)
->union($first)
->get();
The unionAll
method is also available and has the same method signature as union
.
Where Clauses
Simple Where Clauses
To add where
clauses to the query, use the where
method on a query builder instance. The most basic call to where
requires three arguments. The first argument is the name of the column. The second argument is an operator, which can be any of the database‘s supported operators. The third argument is the value to evaluate against the column.
For example, here is a query that verifies the value of the "votes" column is equal to 100:
$users = DB::table(‘users‘)->where(‘votes‘, ‘=‘, 100)->get();
For convenience, if you simply want to verify that a column is equal to a given value, you may pass the value directly as the second argument to the where
method:
$users = DB::table(‘users‘)->where(‘votes‘, 100)->get();
Of course, you may use a variety of other operators when writing a where
clause:
$users = DB::table(‘users‘)
->where(‘votes‘, ‘>=‘, 100)
->get();
$users = DB::table(‘users‘)
->where(‘votes‘, ‘<>‘, 100)
->get();
$users = DB::table(‘users‘)
->where(‘name‘, ‘like‘, ‘T%‘)
->get();
Or Statements
You may chain where constraints together, as well as add or
clauses to the query. The orWhere
method accepts the same arguments as the where
method:
$users = DB::table(‘users‘)
->where(‘votes‘, ‘>‘, 100)
->orWhere(‘name‘, ‘John‘)
->get();
Additional Where Clauses
whereBetween
The whereBetween
method verifies that a column‘s value is between two values:
$users = DB::table(‘users‘)
->whereBetween(‘votes‘, [1, 100])->get();
whereNotBetween
The whereNotBetween
method verifies that a column‘s value lies outside of two values:
$users = DB::table(‘users‘)
->whereNotBetween(‘votes‘, [1, 100])
->get();
whereIn / whereNotIn
The whereIn
method verifies that a given column‘s value is contained within the given array:
$users = DB::table(‘users‘)
->whereIn(‘id‘, [1, 2, 3])
->get();
The whereNotIn
method verifies that the given column‘s value is not contained in the given array:
$users = DB::table(‘users‘)
->whereNotIn(‘id‘, [1, 2, 3])
->get();
whereNull / whereNotNull
The whereNull
method verifies that the value of the given column is NULL
:
$users = DB::table(‘users‘)
->whereNull(‘updated_at‘)
->get();
The whereNotNull
method verifies that the column‘s value is not NULL
:
$users = DB::table(‘users‘)
->whereNotNull(‘updated_at‘)
->get();
Advanced Where Clauses
Parameter Grouping
Sometimes you may need to create more advanced where clauses such as "where exists" or nested parameter groupings. The Laravel query builder can handle these as well. To get started, let‘s look at an example of grouping constraints within parenthesis:
DB::table(‘users‘)
->where(‘name‘, ‘=‘, ‘John‘)
->orWhere(function ($query) {
$query->where(‘votes‘, ‘>‘, 100)
->where(‘title‘, ‘<>‘, ‘Admin‘);
})
->get();
As you can see, passing Closure
into the orWhere
method instructs the query builder to begin a constraint group. The Closure
will receive a query builder instance which you can use to set the constraints that should be contained within the parenthesis group. The example above will produce the following SQL:
select * from users where name = ‘John‘ or (votes > 100 and title <> ‘Admin‘)
Exists Statements
The whereExists
method allows you to write where exist
SQL clauses. The whereExists
method accepts a Closure
argument, which will receive a query builder instance allowing you to define the query that should be placed inside of the "exists" clause:
DB::table(‘users‘)
->whereExists(function ($query) {
$query->select(DB::raw(1))
->from(‘orders‘)
->whereRaw(‘orders.user_id = users.id‘);
})
->get();
The query above will produce the following SQL:
select * from users
where exists (
select 1 from orders where orders.user_id = users.id
)
Ordering, Grouping, Limit, & Offset
orderBy
The orderBy
method allows you to sort the result of the query by a given column. The first argument to the orderBy
method should be the column you wish to sort by, while the second argument controls the direction of the sort and may be either asc
or desc
:
$users = DB::table(‘users‘)
->orderBy(‘name‘, ‘desc‘)
->get();
groupBy / having / havingRaw
The groupBy
and having
methods may be used to group the query results. The having
method‘s signature is similar to that of the where
method:
$users = DB::table(‘users‘)
->groupBy(‘account_id‘)
->having(‘account_id‘, ‘>‘, 100)
->get();
The havingRaw
method may be used to set a raw string as the value of the having
clause. For example, we can find all of the departments with sales greater than $2,500:
$users = DB::table(‘orders‘)
->select(‘department‘, DB::raw(‘SUM(price) as total_sales‘))
->groupBy(‘department‘)
->havingRaw(‘SUM(price) > 2500‘)
->get();
skip / take
To limit the number of results returned from the query, or to skip a given number of results in the query (OFFSET
), you may use the skip
and take
methods:
$users = DB::table(‘users‘)->skip(10)->take(5)->get();
Inserts
The query builder also provides an insert
method for inserting records into the database table. The insert
method accepts an array of column names and values to insert:
DB::table(‘users‘)->insert(
[‘email‘ => ‘[email protected]‘, ‘votes‘ => 0]
);
You may even insert several records into the table with a single call to insert
by passing an array of arrays. Each array represents a row to be inserted into the table:
DB::table(‘users‘)->insert([
[‘email‘ => ‘[email protected]‘, ‘votes‘ => 0],
[‘email‘ => ‘[email protected]‘, ‘votes‘ => 0]
]);
Auto-Incrementing IDs
If the table has an auto-incrementing id, use the insertGetId
method to insert a record and then retrieve the ID:
$id = DB::table(‘users‘)->insertGetId(
[‘email‘ => ‘[email protected]‘, ‘votes‘ => 0]
);
Note: When using PostgreSQL the insertGetId method expects the auto-incrementing column to be named
id
. If you would like to retrieve the ID from a different "sequence", you may pass the sequence name as the second parameter to theinsertGetId
method.
Updates
Of course, in addition to inserting records into the database, the query builder can also update existing records using the update
method. The update
method, like the insert
method, accepts an array of column and value pairs containing the columns to be updated. You may constrain the update
query using where
clauses:
DB::table(‘users‘)
->where(‘id‘, 1)
->update([‘votes‘ => 1]);
Increment / Decrement
The query builder also provides convenient methods for incrementing or decrementing the value of a given column. This is simply a short-cut, providing a more expressive and terse interface compared to manually writing the update
statement.
Both of these methods accept at least one argument: the column to modify. An second argument may optionally be passed to control the amount by which the column should be incremented / decremented.
DB::table(‘users‘)->increment(‘votes‘);
DB::table(‘users‘)->increment(‘votes‘, 5);
DB::table(‘users‘)->decrement(‘votes‘);
DB::table(‘users‘)->decrement(‘votes‘, 5);
You may also specify additional columns to update during the operation:
DB::table(‘users‘)->increment(‘votes‘, 1, [‘name‘ => ‘John‘]);
Deletes
Of course, the query builder may also be used to delete records from the table via the delete
method:
DB::table(‘users‘)->delete();
You may constrain delete
statements by adding where
clauses before calling the delete
method:
DB::table(‘users‘)->where(‘votes‘, ‘<‘, 100)->delete();
If you wish to truncate the entire table, which will remove all rows and reset the auto-incrementing ID to zero, you may use the truncate
method:
DB::table(‘users‘)->truncate();
Pessimistic Locking
The query builder also includes a few functions to help you do "pessimistic locking" on your select
statements. To run the statement with a "shared lock", you may use the sharedLock
method on a query. A shared lock prevents the selected rows from being modified until your transaction commits:
DB::table(‘users‘)->where(‘votes‘, ‘>‘, 100)->sharedLock()->get();
Alternatively, you may use the lockForUpdate
method. A "for update" lock prevents the rows from being modified or from being selected with another shared lock:
DB::table(‘users‘)->where(‘votes‘, ‘>‘, 100)->lockForUpdate()->get();