Schema builder (columns, types) in Laravel - Step-by-Step Execution

Concept Flow - Schema builder (columns, types)

Start Migration

↓

Create Schema Builder Instance

↓

Define Table Name

↓

Add Columns with Types

↓

Set Column Options (nullable, default, etc.)

↓

Run Migration to Create Table

↓

Table Created in Database

This flow shows how Laravel's schema builder creates a table by defining columns and their types step-by-step.

Execution Sample

Laravel

Schema::create('users', function (Blueprint $table) {
  $table->id();
  $table->string('name');
  $table->integer('age')->nullable();
  $table->timestamps();
});

This code creates a 'users' table with an id, a name column, an optional age column, and timestamp columns.

Execution Table

Step	Action	Column Added	Type	Options
1	Start Schema::create	None	None	None
2	$table->id()	id	bigint (auto-increment)	Primary key
3	$table->string('name')	name	string (varchar)	Required
4	$table->integer('age')->nullable()	age	integer	Nullable
5	$table->timestamps()	created_at, updated_at	timestamp	Nullable, default NULL
6	End Schema::create	Table 'users' created	N/A	N/A

💡 All columns defined and table created in database

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	After Step 5	Final
columns	[]	[id]	[id, name]	[id, name, age]	[id, name, age, created_at, updated_at]	[id, name, age, created_at, updated_at]

Key Moments - 2 Insights

Why does $table->integer('age')->nullable() allow null values?

Because the nullable() method sets the column to accept NULL, as shown in step 4 of the execution_table where 'age' column options include Nullable.

What does $table->timestamps() add to the table?

It adds two timestamp columns: created_at and updated_at, which are nullable by default, as shown in step 5 of the execution_table.

Visual Quiz - 3 Questions

Look at the execution table, what type is assigned to the 'id' column at step 2?

A integer

B string

C bigint (auto-increment)

D timestamp

💡 Hint

Check the 'Type' column in row for step 2 in execution_table

At which step are the timestamp columns created?

A Step 3

B Step 5

C Step 4

D Step 6

💡 Hint

Look for $table->timestamps() action in execution_table

If we remove ->nullable() from the 'age' column, what changes in the options column at step 4?

A Options will be empty (not nullable)

B Options will include Nullable

C Type changes to string

D Column is removed

💡 Hint

Compare options for 'age' column in step 4 with and without nullable() in execution_table

Concept Snapshot

Laravel Schema Builder:
- Use Schema::create('table', fn(Blueprint $table) => {...})
- Add columns: $table->string('name'), $table->integer('age')->nullable()
- Common types: id(), string(), integer(), timestamps()
- Use nullable() to allow NULL values
- Run migration to create table in DB

Full Transcript

This visual execution shows how Laravel's schema builder creates a database table step-by-step. First, the migration starts and Schema::create is called with the table name 'users'. Then columns are added one by one: an auto-incrementing id, a required string 'name', an integer 'age' that can be null, and timestamp columns for created_at and updated_at. Each step updates the columns list. Nullable columns allow empty values. The timestamps method adds two timestamp columns. Finally, the table is created in the database with all defined columns.

Practice

1. What does the Schema::create method do in Laravel migrations?

easy

A. Creates a new database table with specified columns

B. Deletes an existing database table

C. Updates data inside a table

D. Runs raw SQL queries directly

Solution

1. Step 1: Understand the purpose of Schema::create

   This method is used to define a new table structure in the database.

2. Step 2: Recognize the role of columns inside the callback

   The callback function receives a Blueprint object to define columns for the new table.

3. Final Answer:

   Creates a new database table with specified columns -> Option A

4. Quick Check:

   Schema::create = create table [OK]

Hint: Schema::create always defines a new table [OK]

Common Mistakes:

• Confusing create with drop or update
• Thinking it modifies data instead of structure
• Assuming it runs raw SQL

2. Which of the following is the correct syntax to add a string column named title in a Laravel migration?

easy

A. $table->varchar('title');

B. $table->string('title');

C. $table->text('title');

D. $table->char('title');

Solution

1. Step 1: Identify the correct method for string columns

   Laravel uses string() to create VARCHAR columns.

2. Step 2: Check the syntax for adding a column

   The syntax is $table->string('column_name'); which matches $table->string('title');.

3. Final Answer:

   $table->string('title'); -> Option B

4. Quick Check:

   String column = $table->string('name') [OK]

Hint: Use $table->string() for VARCHAR columns [OK]

Common Mistakes:

• Using varchar() which does not exist
• Confusing text() with string()
• Using char() without length

3. What will be the resulting column type in the database for this migration code?

$table->integer('age')->unsigned();

medium

A. Unsigned integer column

B. Signed integer column

C. String column named 'age'

D. Boolean column

Solution

1. Step 1: Understand the integer() method

   This creates an integer type column in the database.

2. Step 2: Analyze the effect of unsigned()

   The unsigned() modifier makes the integer only accept positive values (no negatives).

3. Final Answer:

   Unsigned integer column -> Option A

4. Quick Check:

   integer()->unsigned() = unsigned int [OK]

Hint: unsigned() means no negative numbers allowed [OK]

Common Mistakes:

• Ignoring unsigned modifier
• Thinking integer() creates string
• Confusing with boolean type

4. Identify the error in this migration code snippet:

Schema::create('users', function (Blueprint $table) {
    $table->string('email')->nullable;
});

medium

A. String columns cannot be nullable

B. Wrong method name, should be allowNull()

C. Blueprint object is not imported

D. Missing parentheses after nullable method

Solution

1. Step 1: Check the nullable method usage

   In Laravel, nullable is a method and must be called with parentheses ().

2. Step 2: Identify the missing parentheses

   The code uses nullable without (), causing a syntax error.

3. Final Answer:

   Missing parentheses after nullable method -> Option D

4. Quick Check:

   nullable() requires parentheses [OK]

Hint: Always add () after nullable method [OK]

Common Mistakes:

• Writing nullable without ()
• Using allowNull() instead of nullable()
• Assuming string can't be nullable

5. You want to create a table with a primary key id that auto-increments, a nullable description text column, and a price decimal column with 8 digits total and 2 decimal places. Which migration code is correct?

hard

A. Schema::create('products', function (Blueprint $table) { $table->bigIncrements('id'); $table->text('description'); $table->decimal('price', 8, 2); });

B. Schema::create('products', function (Blueprint $table) { $table->integer('id')->autoIncrement(); $table->string('description')->nullable; $table->decimal('price', 8); });

C. Schema::create('products', function (Blueprint $table) { $table->increments('id'); $table->text('description')->nullable(); $table->decimal('price', 8, 2); });

D. Schema::create('products', function (Blueprint $table) { $table->increments('id'); $table->text('description')->nullable; $table->decimal('price', 8, 2); });

Solution

1. Step 1: Check primary key and auto-increment

   $table->increments('id') creates an auto-incrementing primary key integer column.

2. Step 2: Verify nullable text column syntax

   $table->text('description')->nullable(); correctly makes the text column nullable with parentheses.

3. Step 3: Confirm decimal column precision

   $table->decimal('price', 8, 2); defines a decimal with 8 digits total and 2 decimal places.

4. Final Answer:

   Schema::create('products', function (Blueprint $table) { $table->increments('id'); $table->text('description')->nullable(); $table->decimal('price', 8, 2); }); -> Option C

5. Quick Check:

   increments + nullable() + decimal(8,2) = correct [OK]

Hint: Use increments() for PK, nullable() with (), decimal needs precision [OK]

Common Mistakes:

• Forgetting parentheses on nullable()
• Using autoIncrement() instead of increments()
• Missing decimal precision arguments