Executing queries with query method in PHP - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the query method do in PHP's mysqli?

The query method sends an SQL query to the database and returns the result set or false if the query fails.

beginner

How do you check if a query was successful in PHP?

You check if the result of $mysqli->query() is not false. If it is false, the query failed.

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What type of value does query return for a SELECT statement?

It returns a mysqli_result object which you can use to fetch rows from the result set.

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What does query return for an INSERT, UPDATE, or DELETE statement?

It returns true if the query was successful, or false if it failed.

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How do you fetch rows from the result of a query?

Use methods like fetch_assoc() on the mysqli_result object to get rows as associative arrays.

What does $mysqli->query() return when a SELECT query is successful?

A True

B False

C A mysqli_result object

D An integer

For SELECT queries, query returns a mysqli_result object to fetch rows.

What does $mysqli->query() return when an INSERT query is successful?

A A mysqli_result object

B True

C False

D Null

For INSERT, UPDATE, DELETE queries, query returns true on success.

How can you check if a query failed?

A Check if <code>query</code> returns <code>false</code>

B Check if <code>query</code> returns <code>true</code>

C Check if <code>query</code> returns a string

D Check if <code>query</code> returns an integer

If query returns false, the query failed.

Which method do you use to get rows from a mysqli_result object?

A execute()

B query()

C connect()

D fetch_assoc()

Use fetch_assoc() to get rows as associative arrays.

What happens if you run query with a wrong SQL syntax?

A It returns false

B It returns true

C It returns an empty result

D It throws an exception automatically

If the SQL syntax is wrong, query returns false.

Explain how to use the query method to run a SELECT statement and get results.

Think about sending the query, checking success, and reading rows.

Describe what the query method returns for different types of SQL statements.

Consider the difference between queries that return data and those that just change data.