Since DCE 1.2 you are able to map the field values of your DCEs to tt_content columns. DCE is also able to create new columns if necessary.
When creating new columns the following options have the following effect:
New TCA field name: Name of the column in database and TCA. You are free to choose the name. Nothing gets prepended. It is recommended to
New TCA field type: This is the type of field in the database. Example:
varchar(255) DEFAULT '' NOT NULL. You can also use the keyword
auto. DCE will choose a proper SQL field type based on chosen configuration type in FlexForm.
Of course, you can also choose an existing tt_content column. DCE introduced the tx_dce_index column which can get used to index content for search engines (like ke_search or solr).
Since DCE 2.2, contents of DCE fields which has been mapped with "tx_dce_index", are also searched for when using the global LiveSearch in TYPO3 backend. Since TYPO3 9.2 the search in list view, also respects "tx_dce_index" contents.
When you point two DCE fields (or more) to the same TCA column, the contents of the field become appended
Every time you change a content element based on DCE with TCA mappings, the TCA values will get written, when saving/creating the content element.
If you want to update the values, you can call an update script (Update TCA mappings) in DCE backend module.