Querying Database with wpdb

I tested your all attempts in a shortcode:

function add_test_shortcode() {
  global $wpdb;
  global $post;
  $post_ID = $post->ID;
  $wpdb->show_errors = true;
  $result = $wpdb->get_var('SELECT meta_value FROM '.$wpdb->postmeta.' WHERE meta_key="my_test" AND post_id=' . $post_ID);

  return $result;
}
add_shortcode( 'test', 'add_test_shortcode' );

It worked perfectly for me, so there might something from your own code:

1. Check for $post_ID

Make sure your $post_ID is valid, get_the_ID() might be a better replacement in so many cases than global $post;.

2. Test your generated query

You can get your last executed query using $wpdb->last_query, execute it in phpMyAdmin or any other software and check that there is really a result.

3. Look if there’s any error

You can get the latest error statement using $wpdb->last_error.

My advice to you during WordPress development is that always keep WP_DEBUG on.

Related Posts:

  1. how to get serialized post meta
  2. Order by in foreach
  3. How to update custom fields using the wp_insert_post() function?
  4. Can i use php sql functions instead of $wpdb?
  5. wpdb::prepare was called incorrectly
  6. Custom query to get post names beginning with a digit
  7. Display all meta for a post?
  8. PHP syntax error when using wpdb update?
  9. “The plugin generated 2694 characters of unexpected output…” on Plugin activation, CREATE TABLE sql command not working
  10. how to increase custom post value by one most efficiently?
  11. How to Display Image Meta underneath EVERY image in EVERY post
  12. Ajax $wpdb not returning table data
  13. Converting MYSQL to WordPress $WPDB
  14. How to Fetch values from WP database based on selected option value by onchange using PHP?
  15. Get Current User Id Inside a Loop Returns 0 For a Shortcode
  16. Get stock by custom meta field on all Woocommerce variable products
  17. Display fields as values in array from external SQL DB
  18. Can’t get wp_insert_post to work
  19. Trying to establish connection to External Database
  20. Randomly Assign an Image’s Alt Text Based on Data From Post
  21. Getting id of poll from WP database
  22. How to insert a single row to WP database table?
  23. Advanced Meta Query for Large Calendar Website (12k+ posts) (175k+ wp_postmeta rows)
  24. I want to select the from values from database in WordPress? [closed]
  25. $wpdb->update with multiple parameters gives error
  26. How to VAR_DUMP a $variable during checkout process (Is my product meta callable?)
  27. wp query foreach deleting record returning only first or last item
  28. Using $wpdb (WPDB class) ‘replace’ with multiple WHERE criteria problem
  29. WordPress update_post_meta updating with empty meta_value field [closed]
  30. Non-Closing PHP Query in WordPress Loop
  31. Custom array from a query only write the last row of the query
  32. $wpdb returns duplicate posts
  33. update_post_meta only updating on last loop of foreach
  34. Wpdb->insert() doesn’t insert new row after the last one
  35. Use $wpdb or other PHP script method to find/replace in WP database
  36. How to get specific attribute from DB
  37. WordPress loop by meta key that is an array? and how loop multiple arrays
  38. wpdb Cannot Update column in Database
  39. PHP -> SQL Query with Summing
  40. How to insert wp_users ->user login name to wp_terms when a new user registering?
  41. How to add post meta in while loop?
  42. Add category to post meta
  43. How do I prepare strings for insertions as values into a MySQL table?
  44. Change MySQL PDO connection to a WPDB connection
  45. WPDB – Read and write value from / to database
  46. Order a WP_Query by meta value where the value is an array
  47. $wpdb->get_results breaking page?
  48. Add a custom class to the body tag using custom fields
  49. How to Generate a list of Most Commented post?
  50. Why won’t this wpdb get_results query return results?
  51. WPDB secure custom form
  52. Unable to Call More than One Meta Box Output
  53. Hide a div when a custom field is empty
  54. Call to a member function get_row() on a non-object, Unable to use global $wbdp inside a plugin
  55. Post meta select input, if statement
  56. Query the links Database
  57. WordPress stripping out custom field tags
  58. WordPress get last inserted user id
  59. Isn’t Returning Value While Using SELECT COUNT(*) FROM {$wpdb->prefix}
  60. WordPress SQL Prepare
  61. How to update custom fields when post is published?
  62. Update Images after edit via php
  63. No more get_option(‘date_time’) in WordPress 5.5?
  64. Delete post meta by serialized meta value
  65. What is the correct way to search 3 custom fields only in WordPress?
  66. Using wpdb to connect to a different database is not working
  67. Show a text if the post has written by author user role in WordPress
  68. Looping through custom data in a custom table to display all items in a post
  69. Fix common misspellings/errors based on array of replacements
  70. WP post meta – for loop inside for loop
  71. Reverse Cross-Sells (WooCommerce)
  72. Remove item from post_meta array via AJAX
  73. Post Meta statement?
  74. Rewrite SQL query as a prepared statement and use in foreach loop
  75. How to return count of items found in SQL query
  76. WordPress AJAX load post metadata in modal
  77. get_post_meta with variable
  78. Accessing external database: ERR_INCOMPLETE_CHUNKED_ENCODING
  79. Post from front end form to post_meta
  80. Run insert if no entry otherwise run update with ajax
  81. MySQL queries in WordPress
  82. At what point during a typical request does the $wpdb object become available?
  83. Postmeta not saving
  84. If custom field doesn’t exist, or exists and it’s true show title?
  85. Get null from POST
  86. MySQL database migration to WordPress
  87. How to add together (get the sum) a field from all author’s posts
  88. Insert into db with foreach problem
  89. posts_clauses drop ACF get_field function
  90. WordPress Query -> Ajax Query
  91. how to display tables via ajax
  92. Changing regular db connection to $wpdb
  93. Can’t send form data to wpdb when URL has query string
  94. use wpdb object on other file
  95. How do I get a function to work in single.php
  96. $wpdb how to make a record lookup
  97. Error resetting database index using ALTER TABLE in $wpdb->query
  98. Warning: Undefined property: wpdb::$question_overview in C:\Wamp.NET\sites\proxyvragenmodule\wordpress\wp-includes\class-wpdb.php
  99. WordPress / PHP: Check if column has value and then check if value in array
  100. How to modify default tags in wp_head()
deneme bonusu veren sitelerbahis casinomakrobetceltabetpinbahispolobetpolobet girişpinbahis girişmakrobet girişpulibet girişmobilbahis girişkolaybet giriş