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SELECT QUERIES from PHP

• SELECT queries return a ‘table’ of data known as a result set.
• SELECT queries are run using MySQLi->query() and will return a MySQLi_Result object, which is a class is used to represent result sets returned from SELECT queries.
  • It has the property num_rows which holds the number of rows in the result set.
  • It has the following methods for processing the result set, which will return NULL if there are no more rows in the result set:
    • fetch_assoc() – fetch a row of the result set & return it as an associative array
    • fetch_object() – fetch a row of the result set & return it as an object of class stdClass
• fetch_assoc() returns the next row of a result set as an associative array with the keys of the array being the names of the columns in the result set.
• PHP has a built-in class called stdClass that can be used to hold data in object form as object properties. All of the properties of an instance of a stdClass object are publicly accessible.
• fetch_object() returns the next row of a result set as a stdClass object with property names matching the names of the columns in the result set.
• MySQLi_Result->free()is used to free memory used by a result set. It should always be called after the processing of a result set is finished.
• Additional Resources:
  • Class Reference - MySQLi_Result Class
  • Object Method Reference - MySQLi_Result->fetch_assoc()
  • Object Method Reference - MySQLi_Result->fetch_object()
  • Object Method Reference - MySQLi_Result->free()