Fetching results (fetch, fetchAll) in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the fetch() method do in PHP PDO?

The fetch() method retrieves the next row from a result set as an array or object. It returns one row at a time or false if no more rows are available.

beginner

How is fetchAll() different from fetch()?

fetchAll() retrieves all remaining rows from the result set at once as an array of arrays or objects, while fetch() gets one row at a time.

intermediate

What is a common use case for fetch()?

Use fetch() when you want to process rows one by one, for example, in a loop to handle large data sets without loading everything into memory.

beginner

What does fetchAll(PDO::FETCH_ASSOC) return?

It returns all rows as an array of associative arrays, where each array uses column names as keys.

beginner

What happens if you call fetch() after all rows have been fetched?

It returns false, indicating there are no more rows to fetch.

Which method fetches all rows from a PDO statement at once?

A prepare()

B fetch()

C execute()

D fetchAll()

fetchAll() retrieves all rows at once, while fetch() retrieves one row at a time.

What does fetch() return when no more rows are available?

A false

B null

C empty array

D 0

fetch() returns false when there are no more rows to fetch.

Which fetch style returns rows as associative arrays with column names as keys?

A PDO::FETCH_NUM

B PDO::FETCH_OBJ

C PDO::FETCH_ASSOC

D PDO::FETCH_BOTH

PDO::FETCH_ASSOC returns rows as associative arrays keyed by column names.

When is it better to use fetch() instead of fetchAll()?

A When you want all rows at once

B When processing large data sets row by row

C When you want to prepare a statement

D When you want to execute a query

fetch() is better for large data sets to avoid loading all rows into memory at once.

What type of value does fetchAll() return?

A An array of rows

B An integer

C A boolean

D A single row

fetchAll() returns an array containing all rows from the result set.

Explain the difference between fetch() and fetchAll() in PHP PDO.

Think about how many rows each method returns and memory usage.

Describe a scenario where using fetch() is better than fetchAll().

Consider memory and performance when handling many rows.