Select queries in Laravel - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to select all records from the 'users' table using Laravel's query builder.

Laravel

$users = DB::table('users')->[1]();

Drag options to blanks, or click blank then click option'

Aget

Bselect

Call

Dfetch

Attempts:

3 left

💡 Hint

Common Mistakes

Using select() instead of get() to fetch data.

Using all() which is not a query builder method.

The get() method retrieves all records from the query builder in Laravel.

2fill in blank

medium

Complete the code to select only the 'name' and 'email' columns from the 'users' table.

Laravel

$users = DB::table('users')->[1](['name', 'email'])->get();

Drag options to blanks, or click blank then click option'

Aselect

Bpluck

Ccolumns

Dget

Attempts:

3 left

💡 Hint

Common Mistakes

Using get() with columns array which causes error.

Using pluck() when multiple columns are needed.

The select() method specifies which columns to retrieve in Laravel's query builder.

3fill in blank

hard

Fix the error in the code to get the first user with id 5.

Laravel

$user = DB::table('users')->where('id', [1])->first();

Drag options to blanks, or click blank then click option'

A'5'

Bid

C"5"

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Passing '5' as a string instead of integer 5.

Using the column name 'id' as value.

The where method expects the actual value without quotes for integers. Using 5 (integer) is correct.

4fill in blank

hard

Fill both blanks to select users where 'status' is 'active' and order by 'created_at' descending.

Laravel

$users = DB::table('users')->where('status', [1])->orderBy([2], 'desc')->get();

Drag options to blanks, or click blank then click option'

A'active'

B'created_at'

C'status'

D'desc'

Attempts:

3 left

💡 Hint

Common Mistakes

Using column names instead of values in where clause.

Putting 'desc' in place of column name in orderBy.

The where method needs the value 'active' for status, and orderBy needs the column name 'created_at' to sort by date.

5fill in blank

hard

Fill all three blanks to select 'name' and 'email' of users older than 18, ordered by 'name' ascending.

Laravel

$users = DB::table('users')->select([1], [2])->where('age', '>', [3])->orderBy('name', 'asc')->get();

Drag options to blanks, or click blank then click option'

A'name'

B'email'

C18

D'age'

Attempts:

3 left

💡 Hint

Common Mistakes

Using column name 'age' as a value in where clause.

Forgetting quotes around column names in select.

The select method needs the column names 'name' and 'email'. The where clause compares 'age' to the number 18.

Practice

1. What does the select() method do in a Laravel query builder?

easy

A. It specifies which columns to retrieve from the database.

B. It inserts new data into the database.

C. It deletes rows from the database table.

D. It updates existing records in the database.

Solution

1. Step 1: Understand the purpose of select()

   The select() method tells Laravel which columns you want to get from the database table.

2. Step 2: Compare with other query methods

   Methods like insert(), delete(), and update() perform different actions, not selecting columns.

3. Final Answer:

   It specifies which columns to retrieve from the database. -> Option A

4. Quick Check:

   select() chooses columns [OK]

Hint: Remember: select() picks columns, not rows or actions [OK]

Common Mistakes:

• Confusing select() with insert() or update()
• Thinking select() deletes data
• Assuming select() fetches all columns by default

2. Which of the following is the correct syntax to select the columns 'name' and 'email' from the 'users' table using Laravel's query builder?

easy

A. DB::table('users')->select(['name', 'email'])->get();

B. DB::table('users')->select('name' & 'email')->get();

C. DB::table('users')->select('name, email')->get();

D. DB::table('users')->select('name' + 'email')->get();

Solution

1. Step 1: Check the correct way to pass multiple columns

   Laravel's select() accepts an array of column names to select multiple columns.

2. Step 2: Analyze each option's syntax

   DB::table('users')->select('name, email')->get(); uses select('name, email'), which selects a single column named 'name, email'. Options B and D use invalid operators & and +. DB::table('users')->select(['name', 'email'])->get(); correctly uses an array ['name', 'email'].

3. Final Answer:

   DB::table('users')->select(['name', 'email'])->get(); -> Option A

4. Quick Check:

   Use array for multiple columns in select() [OK]

Hint: Use array syntax for multiple columns in select() [OK]

Common Mistakes:

• Passing multiple strings without array
• Using operators like + or & inside select()
• Forgetting to call get() to execute query

3. What will be the output of the following Laravel query?

DB::table('products')->select('name')->where('price', '>', 100)->get();

medium

A. All products with price greater than 100, showing all columns.

B. All products with price less than or equal to 100, showing only their names.

C. All products with price greater than 100, showing only their names.

D. Syntax error due to incorrect where clause.

Solution

1. Step 1: Understand the where condition

   The query filters products where the price is greater than 100.

2. Step 2: Understand the select clause

   Only the 'name' column is selected, so only product names will be returned.

3. Final Answer:

   All products with price greater than 100, showing only their names. -> Option C

4. Quick Check:

   where('price', '>', 100) filters price > 100 [OK]

Hint: where() filters rows; select() chooses columns [OK]

Common Mistakes:

• Confusing > with < in where clause
• Expecting all columns instead of selected ones
• Thinking where() causes syntax error here

4. Identify the error in this Laravel query:

DB::table('orders')->select('id', 'total')->where('status' = 'pending')->get();

medium

A. Using '=' instead of '==' in where clause.

B. Using '=' instead of ',' to separate arguments in where().

C. Missing semicolon at the end of the query.

D. select() cannot take multiple columns.

Solution

1. Step 1: Check the where clause syntax

   The where method expects two arguments separated by a comma, not an assignment with '='.

2. Step 2: Identify the correct syntax

   The correct syntax is where('status', 'pending'), not where('status' = 'pending').

3. Final Answer:

   Using '=' instead of ',' to separate arguments in where(). -> Option B

4. Quick Check:

   where() needs comma between arguments [OK]

Hint: Use comma, not =, between where() arguments [OK]

Common Mistakes:

• Using = instead of comma in where()
• Confusing assignment with comparison
• Thinking select() can't take multiple columns

5. You want to get the 'id' and 'email' of users who are active and have verified their email. Which Laravel query correctly does this?

hard

A. DB::table('users')->select(['id', 'email'])->where('active' = 1)->where('email_verified' = 1)->get();

B. DB::table('users')->select('id', 'email')->where('active' == 1 && 'email_verified' == 1)->get();

C. DB::table('users')->select(['id', 'email'])->where('active', '=', 1, 'email_verified', '=', 1)->get();

D. DB::table('users')->select(['id', 'email'])->where(['active' => 1, 'email_verified' => 1])->get();

Solution

1. Step 1: Understand filtering multiple conditions

   Laravel allows passing an associative array to where() to filter multiple columns with AND logic.

2. Step 2: Analyze each option

   DB::table('users')->select(['id', 'email'])->where(['active' => 1, 'email_verified' => 1])->get(); correctly uses where(['active' => 1, 'email_verified' => 1]). DB::table('users')->select('id', 'email')->where('active' == 1 && 'email_verified' == 1)->get(); uses invalid syntax with == and && inside where(). DB::table('users')->select(['id', 'email'])->where('active', '=', 1, 'email_verified', '=', 1)->get(); passes too many arguments to a single where(). DB::table('users')->select(['id', 'email'])->where('active' = 1)->where('email_verified' = 1)->get(); uses = instead of , to separate where() arguments, causing syntax error.

3. Final Answer:

   DB::table('users')->select(['id', 'email'])->where(['active' => 1, 'email_verified' => 1])->get(); -> Option D

4. Quick Check:

   Use array in where() for multiple AND conditions [OK]

Hint: Use array in where() for multiple AND filters [OK]

Common Mistakes:

• Using invalid operators inside where()
• Passing too many arguments to where()
• Not using array for multiple conditions