PHP MySQLi Connection Basics
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PHP MySQLi Connection Basics

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Questions and Answers

What is the primary purpose of the mysqli_close() function?

  • To close all open connections to any database.
  • To check for errors in the last executed query.
  • To initiate a new database connection.
  • To free up system resources after database queries. (correct)
  • Which function would you use to fetch a result row as a numeric array from a query result?

  • mysqli_fetch_row() (correct)
  • mysqli_fetch_array()
  • mysqli_stmt_execute()
  • mysqli_fetch_assoc()
  • What benefit does mysqli_prepare() provide when executing SQL statements?

  • It prevents SQL injection by separating data from the query structure. (correct)
  • It retrieves the last inserted ID directly.
  • It executes a query immediately after preparation.
  • It automatically closes the database connection.
  • Which function can be used to return the ID generated by the last insert query for an AUTO_INCREMENT column?

    <p>mysqli_insert_id()</p> Signup and view all the answers

    What is the purpose of the mysqli_stmt_bind_param() function?

    <p>It binds variables to prepared statement parameters.</p> Signup and view all the answers

    Which scenario is most appropriate for using mysqli_error()?

    <p>To provide debug information for an unsuccessful query execution.</p> Signup and view all the answers

    In what situation is mysqli_fetch_assoc() preferable to mysqli_fetch_row()?

    <p>When you need to access values by column names instead of numbers.</p> Signup and view all the answers

    What does the mysqli_stmt_execute() function do?

    <p>It executes a prepared statement after parameters have been bound.</p> Signup and view all the answers

    How does using prepared statements with mysqli_prepare() improve database security?

    <p>By preventing SQL injection through parameter binding.</p> Signup and view all the answers

    What function would you use to count the number of rows returned from a query?

    <p>mysqli_num_rows()</p> Signup and view all the answers

    What is the primary purpose of the mysqli_connect() function?

    <p>To establish a new connection to a MySQL database server.</p> Signup and view all the answers

    Which parameter is NOT required by the mysqli_connect() function?

    <p>$dbname</p> Signup and view all the answers

    How can a developer identify issues during a database connection attempt?

    <p>By checking <code>mysqli_connect_error()</code> after a failed connection.</p> Signup and view all the answers

    Which function would you use to perform a SELECT query on a MySQL database?

    <p>mysqli_query()</p> Signup and view all the answers

    What does the mysqli_fetch_assoc() function return?

    <p>A single row as an associative array from a result set.</p> Signup and view all the answers

    What is the function of mysqli_num_rows()?

    <p>To return the number of rows in a result set from a SELECT query.</p> Signup and view all the answers

    What is a common use case for mysqli_query() in a web application?

    <p>To query the database for product details.</p> Signup and view all the answers

    Which of the following statements about mysqli_connect_error() is true?

    <p>It returns an error description if the connection fails.</p> Signup and view all the answers

    Study Notes

    MySQLi Procedural Keywords Overview

    • mysqli_connect(): Initializes a connection to a MySQL database server; parameters include server name, username, password, and optional database name; essential for database interaction.

    • mysqli_connect_error(): Provides error descriptions for the last connection attempt; aids in troubleshooting connectivity issues such as unreachable servers or incorrect credentials.

    • mysqli_query(): Executes SQL queries (SELECT, INSERT, UPDATE, DELETE) on the connected database; requires a connection resource and the SQL statement; fundamental for data manipulation.

    • mysqli_fetch_assoc(): Retrieves a single row from query results as an associative array; allows data access using column names, enhancing readability when processing results.

    • mysqli_num_rows(): Returns the count of rows in a result set from a SELECT query; useful for determining the volume of returned records and managing large data sets.

    • mysqli_close(): Terminates an active database connection; important for resource management by freeing up system connections post-query execution.

    • mysqli_error(): Returns error descriptions from the latest MySQLi function call; invaluable for debugging SQL query failures or connection problems.

    • mysqli_prepare(): Prepares an SQL statement for later execution, with placeholders for data; enhances security by separating the query structure from the actual data to prevent SQL injection.

    • mysqli_stmt_bind_param(): Binds variables to a prepared statement's parameters while specifying data types; fortifies database security by ensuring data integrity.

    • mysqli_stmt_execute(): Executes a prepared statement after binding variables; crucial step for running secured SQL queries.

    • mysqli_fetch_row(): Fetches results as a numeric array; provides an alternative method of data retrieval via column indices, useful for various applications.

    • mysqli_insert_id(): Retrieves the ID generated by the last query for an AUTO_INCREMENT column; critical for tracking newly inserted records in tables.

    Practical Application of MySQLi Functions in a Project

    • For an online book store, the connection to the database is initiated using mysqli_connect(), enabling access to the book inventory.

    • User queries for book details utilize mysqli_query() to fetch data based on specific search criteria.

    • Error handling is performed with mysqli_error() to manage and debug any issues encountered during query execution.

    • mysqli_fetch_assoc() is employed to display relevant book information, such as title and price, enhancing user experience.

    • The number of search results is determined using mysqli_num_rows(), informing users how many books matched their query, supporting informed decision-making.

    • Finally, mysqli_close() is executed to close the database connection, optimizing application performance and resource utilization.

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    Description

    This quiz covers the essential PHP MySQLi procedural keywords for establishing a connection to a MySQL database. Test your knowledge on functions such as mysqli_connect() and its parameters. Perfect for beginners looking to enhance their backend programming skills.

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