Database Interaction in Wordpress

Question 1

Q: What database management system does WordPress use?

Answer 1

A: MySQL or MariaDB.

Question 2

Q: What is the default table prefix for WordPress tables?

Answer 2

A: wp_.

Question 3

Q: How many default tables are there in a WordPress installation?

Answer 3

A: 12.

Question 4

Q: What table stores post content and metadata?

Answer 4

A: wp_posts.

Question 5

Q: What table stores user information?

Answer 5

A: wp_users.

Question 6

Q: What global object is used for database interaction in WordPress?

Answer 6

A: $wpdb.

Question 7

Q: How do you access the WordPress database prefix in code?

Answer 7

A: $wpdb->prefix.

Question 8

Q: How do you retrieve a specific table name with $wpdb?

Answer 8

A: Use $wpdb->table_name (e.g., $wpdb->posts).

Question 9

Q: What function should you use to prepare SQL queries safely?

Answer 9

A: $wpdb->prepare().

Question 10

Q: Why is it important to prepare SQL queries?

Answer 10

A: To prevent SQL injection vulnerabilities.

Question 11

Q: What method is used to run a SELECT query?

Answer 11

A: $wpdb->get_results().

Question 12

Q: What method is used to fetch a single row from a query?

Answer 12

A: $wpdb->get_row().

Question 13

Q: What method is used to fetch a single value from a query?

Answer 13

A: $wpdb->get_var().

Question 14

Q: What method is used to insert data into a database?

Answer 14

A: $wpdb->insert().

Question 15

Q: What method is used to update data in a database?

Answer 15

A: $wpdb->update().

Question 16

Q: What method is used to delete data from a database?

Answer 16

A: $wpdb->delete().

Question 17

Q: What method is used to execute a custom SQL query?

Answer 17

A: $wpdb->query().

Question 18

Q: What does $wpdb->last_query return?

Answer 18

A: The last SQL query executed by $wpdb.

Question 19

Q: What does $wpdb->num_rows return?

Answer 19

A: The number of rows returned by the last query.

Question 20

Q: What does $wpdb->insert_id return?

Answer 20

A: The ID of the last inserted row.

Question 21

Q: What table stores site settings and options?

Answer 21

A: wp_options.

Question 22

Q: What table links posts to their taxonomies?

Answer 22

A: wp_term_relationships.

Question 23

Q: What table stores taxonomy terms?

Answer 23

A: wp_terms.

Question 24

Q: What table stores term taxonomy data?

Answer 24

A: wp_term_taxonomy.

Question 25

Q: What table stores metadata for posts?

Answer 25

A: wp_postmeta.

Question 26

Q: What should you always use when including variables in SQL queries?

Answer 26

A: $wpdb->prepare().

Question 27

Q: Why should you avoid hardcoding table prefixes?

Answer 27

A: To support sites with custom table prefixes and improve portability.

Question 28

Q: What is the purpose of escaping output in database queries?

Answer 28

A: To prevent XSS attacks by sanitising output before displaying it.

Question 29

Q: What WordPress function can be used to sanitise user input?

Answer 29

A: sanitize_text_field(), esc_sql(), or esc_html().

Question 30

Q: Why is it important to validate input before database operations?

Answer 30

A: To ensure the data meets expected formats and prevent security risks.

Question 31

Q: How do you create a custom database table in WordPress?

Answer 31

A: Use the dbDelta() function in combination with SQL CREATE TABLE statements.

Question 32

Q: What hook is commonly used to create custom database tables?

Answer 32

A: register_activation_hook().

Question 33

Q: What is the purpose of the dbDelta() function?

Answer 33

A: To create or update database tables in a WordPress-friendly way.

Question 34

Q: How do you check if a custom table exists in the database?

Answer 34

A: Query the INFORMATION_SCHEMA or use $wpdb->get_var().

Question 35

Q: What is a common practice for naming custom tables?

Answer 35

A: Prefix them with $wpdb->prefix to avoid conflicts.

Question 36

Q: What function can be used to optimise a WordPress database?

Answer 36

A: wp db optimize with WP-CLI or directly via SQL commands.

Question 37

Q: How do you clean up orphaned metadata in WordPress?

Answer 37

A: Write a custom query to delete unused entries in wp_postmeta or wp_usermeta.

Question 38

Q: Why is it important to index columns in large tables?

Answer 38

A: To improve query performance and reduce load times.

Question 39

Q: What WordPress plugin can be used to monitor database queries?

Answer 39

A: Query Monitor.

Question 40

Q: How do you back up a WordPress database programmatically?

Answer 40

A: Use mysqldump or a plugin like UpdraftPlus.