Drupal 8, 9 Schemas

d8_my_module.install

<?php

use Drupal\Core\Database\Database;

/**
 * Implements hook_schema().
 *
 *  Notes:
 * 'not null' = requiered
 */
function d8_my_module_schema() {

  $schema['demo_schema_table'] = [
    'description' => 'Sample of field types',
    
    'fields' => [
    
      'demo_id' => [
        'description' => 'Auto increment ID',
        'type' => 'serial',
        'unsigned' => TRUE,
        'not null' => TRUE,
      ],

      'demo_string' => [
        'description' => 'Optional string up to 128 characters',
        'type' => 'varchar_ascii',
        'not null' => FALSE,
        'default' => '',
        'length' => 128,
      ],
      
      'demo_long_string' => [
        'description' => 'Long string',
        'type'        => 'varchar_ascii',
        'length'      => \Drupal\Core\Entity\EntityTypeInterface::ID_MAX_LENGTH,
        'not null'    => TRUE,
      ],

      'demo_code' => [
        'description' => '3 characters code',
        'type'        => 'varchar',
        'length'      => 3,
      ],
            
      'demo_int' => [
        'description' => 'unsigned Intiger',
        'type'        => 'int',
        'unsigned'    => TRUE,     
        'not null'    => TRUE,   
      ],
      'unix_timestamp_filed' => [
        'type' => 'int',
        'not null' => TRUE,
        'default' => 0,
        'description' => 'The Unix timestamp.',
      ],

      'boolean' => [
        'description' => 'boolean with a default of TRUE',
        'type' => 'int',
        'not null' => TRUE,
        'default' => 1,
        'size' => 'small',
      ],

      
      'user_id' => [
        'type' => 'int',
        'unsigned' => TRUE,
        'not null' => TRUE,
        'default' => 0,
        'description' => 'The user ID.',
      ],
      
      'demo_number' => [
        'description' => 'Number from 0.00 to 99999999.99',
        'type' => 'numeric',
        'size' => 'normal',
        'not null' => TRUE,
        'default' => 0,
        'precision' => 10,
        'scale' => 2,
      ],

      'data' => [
        'description' => 'Serialized data array',
        'type' => 'blob',
        'not null' => FALSE,
        'size' => 'big',
      ],
    
    'primary key' => ['demo_id'],
    
    'indexes' => [
      'date' => [
        'demo_date',
      ],
      'multi_part' => [
        'demo_string',
        'demo_date'
      ],
    ],
    
    'foreign keys' => [
      'refrenced_user' => [
        'table' => 'users',
        'columns' => [
          'user_id' => 'uid',
        ],
      ],
    ],    
    
}


/**
 * Update hook example of adding a schema table.
 * source: https://www.drupal.org/docs/drupal-apis/update-api/updating-database-schema-andor-data-in-drupal-8
 */
function mymodule_update_8101() {
  $spec = [
    'description' => 'My description',
    'fields' => [
      'myfield1' => [
        'description' => 'Myfield1 description.',
        'type' => 'varchar',
        'length' => 255,
        'not null' => TRUE,
        'default' => '',
      ],
      'myfield2' => [
        'description' => 'Myfield2 description',
        'type' => 'text',
        'not null' => TRUE,
      ],
    ],
    'primary key' => ['myfield1'],
  ];
  $schema = Database::getConnection()->schema();
  $schema->createTable('mytable2', $spec);
}

?>

d8_my_module.views.inc

<?php

// examples. for full details see https://api.drupal.org/api/drupal/core%21modules%21views%21views.api.php/function/hook_views_data/9.0.x

// Add an ID field (numeric)
  $data['test_tbl']['id'] = [
    'title' => t('Table ID'),
    'help' => t('The Table ID.'),
    'field' => [
      'id' => 'numeric',
    ],
    'filter' => [
      'id' => 'numeric',
    ],
    'argument' => [
      'id' => 'numeric',
    ],
    'sort' => [
      'id' => 'standard',
    ],
  ];

// Add an Integer timestamp as a date field 
  $data['test_tbl']['transaction_date'] = [
    'title' => t('Date and time'),
    'help' => t('The date & time.'),
    'field' => [
      'id' => 'date',
    ],
    'sort' => [
      'id' => 'date',
    ],
    'filter' => [
      'id' => 'date',
    ],
  ];

// Text field
  $data['test_tbl']['text_field'] = [
    'title' => t('Text field'),
    'help' => t('Text field'),
    'field' => [
      'id' => 'standard',
    ],
    'argument' => [
      'id' => 'string',
    ],
    'filter' => [
      'id' => 'string',
    ],
    'sort' => [
      'id' => 'standard',
    ],
  ];

  $data['test_tbl']['boolean_field'] = [
    'title' => t('Boolean Field'),
    'help' => t('Field holds a Yes/No value.'),
    'field' => [
      'id' => 'boolean',
    ],
    'sort' => [
      'id' => 'standard',
    ],
    'filter' => [
      'id' => 'boolean',
      'label' => t('import?'),
      'type' => 'yes-no',
    ],
  ];

// Add a node reference field (numeric)
  $data['test_tbl']['node_ref'] = [
    'title' => t('Rreferenced Node ID'),
    'help' => t('The Node ID to reference.'),
    'field' => [
      'id' => 'numeric',
    ],
    'filter' => [
      'id' => 'numeric',
    ],
    'argument' => [
      'id' => 'numeric',
    ],
    'sort' => [
      'id' => 'standard',
    ],
    'relationship' => [
      'base' => 'node_field_data',
      'base field' => 'nid',
      'id' => 'standard',   // plugin ID to handle the relationship
      'label' => t('Node'),
    ],
  ];

  


// Other relationship types
    'relationship' => [
      'base' => 'taxonomy_term',
      'base field' => 'tid',
      'label' => t('Term'),
    ],      
    
    'relationship' => [
      'base' => 'users_field_data',
      'base field' => 'uid',
      'id' => 'standard',
      'label' => t('User'),
    ],
?>