TYPO3 Core

For a label-definition in TCA its a perfectly valid usecase to add a column defined as an integer, be it you want to display the integer itself or displaying data of a parent record referenced in that column.

Consider this definition:

Configuration/TCA/tx_myextension_post.php

return [
    'ctrl' => [
        'title' => 'Post',
        'label' => 'post_title',
        'label_alt_force' => TRUE,
        'label_alt' => 'blog',
    ],
    'types' => ['1' => ['showitem' => 'post_title,blog']],
    'columns' => [
        'post_title' => [
            'label' => 'Post title',
            'config' => [
                'type' => 'input',
            ]
        ],
        'blog' => [
            'label' => 'Blog this Post belongs to',
            'config' => [
                'type' => 'group',
                'internal_type' => 'db',
                'foreign_table' => 'tx_myextension_blog',
                'allowed' => 'tx_myextension_blog',
                'size' => 1,
                'suggestOptions' => [
                    'default' => [
                        'searchWholePhrase' => TRUE
                    ]
                ]
            ]
        ],
    ],
];

Configuration/TCA/tx_myextension_blog.php

return [
    'ctrl' => [
        'title' => 'Blog',
        'label' => 'blog_title',
        'label_alt_force' => TRUE,
        'label_alt' => 'blog_int',
    ],
    'types' => ['1' => ['showitem' => 'blog_title,blog_number']],
    'columns' => [
        'blog_title' => [
            'label' => 'Blog title',
            'config' => [
                'type' => 'input',
            ]
        ],
        'blog_number' => [
            'label' => 'Blog number as an example integer',
            'config' => [
                'type' => 'input',
                'eval' => 'int',
            ]
        ],
    ],
];

ext_tables.sql

CREATE TABLE tx_myextension_post (
 uid int(10) unsigned NOT NULL auto_increment,
 pid int(10) unsigned NOT NULL DEFAULT '0',

 post_title varchar(255) NOT NULL DEFAULT '',
 blog int(10) unsigned NOT NULL DEFAULT '0',

 PRIMARY KEY (uid),
 KEY parent (pid)
);

CREATE TABLE tx_myextension_blog (
 uid int(10) unsigned NOT NULL auto_increment,
 pid int(10) unsigned NOT NULL DEFAULT '0',

 blog_title varchar(255) NOT NULL DEFAULT '',
 blog_number int(10) unsigned NOT NULL DEFAULT '0',

 PRIMARY KEY (uid),
 KEY parent (pid)
);

If you search for a Blog in the suggest wizard of a Post on PostgreSQL you receive a DBAL-DriverException:

(1/3) Doctrine\DBAL\Exception\DriverException

An exception occurred while executing 'SELECT * FROM "tx_myextension_blog" WHERE (("blog_title" LIKE ?) OR ("blog_number" LIKE ?)) LIMIT 50' with params ["%Foo%", "%Foo%"]: SQLSTATE[42883]: Undefined function: 7 FEHLER: Operator existiert nicht: bigint ~~ unknown LINE 1: ...et" WHERE (("blog_title" LIKE $1) OR ("blog_number" LIKE $2)) ... ^ HINT: Kein Operator stimmt mit dem angegebenen Namen und den Argumenttypen überein. Sie müssen möglicherweise ausdrückliche Typumwandlungen hinzufügen.

This happens as blog_number, being an integer and part of a label, is used in a LIKE query