Microsoft Corp and SAP will attend an EU hearing on Oracle Corp's plan to buy Sun Microsystems Inc that could help EU regulators decide whether to clear or block the deal, two people close to the matter said on Tuesday.

The two-day closed hearing starts on Thursday and will allow Oracle, Sun, competitors and interested parties to argue their case in front of officials from the European Commission and European national competition regulators. The European Commission has objected to the $7 billion deal, saying the combination of Sun's MySQL database product and Oracle's products could squeeze competition in the database market, a Sun regulatory filing showed last month.

The Commission has Microsoft , SAP and Monti Widenius and not one customer. Oracle will have eight customers supporting its position at the hearing, one of the people told Reuters.

Widenius, the creator of MySQL and who left Sun earlier this year, told Reuters in an interview last month that he was worried his creation could be killed.

Oracle President Safra Catz and a representative from the Department of Justice, which approved the deal in August, will attend the hearing, the second person told Reuters.

Eben Moglen, founding director of the Software Freedom Law Center and who has pointed out flaws in the Commission's analysis of the deal, will also participate. The Commission has set a January 27 deadline for its decision on the takeover.

Oracle has until December 14 to submit remedies to address the European Union executive's concerns on the competitive impact of the deal. It has said MySQL will improve its competitive edge against Microsoft.

MySQL database is used to run popular websites operated by companies such as Google Inc , Facebook and Amazon.com . Its primary competitor is Microsoft's SQL Server.

(Reporting by Foo Yun Chee; Editing by Richard Chang)

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