reveal to the American people all information about the database "Main Core" created without warrants or court orders.

Main Core is the code name of a database maintained since the 1980s by the federal government of the United States. Main Core contains personal and financial data of millions of U.S. citizens believed to be threats to national security. The data, which comes from the NSA, FBI, CIA, and other sources, is collected and stored without warrants or court orders. The database's name derives from the fact that it contains "copies of the 'main core' or essence of each item of intelligence information on Americans produced by the FBI and the other agencies of the U.S. intelligence community."
The Main Core database is believed to have originated with the Federal Emergency Management Agency (FEMA) in 1982, following Ronald Reagan's Continuity of Operations (source of this description: Wikipedia)