Is a Confidentiality Agreement enforceable during a deposition under subpoena.?

In every confidentiality contract I prepare, the non-disclosure obligation does not apply under various circumstances, including when disclosure is compelled under a valid subpoena.  Even without such a provision, a valid subpoena trumps your contract with your former employer.  Sometimes a confidentiality provision does require the subpoenaed party to notify the other party about the subpoena, so that the party who wants to keep the information confidential can challenge the subpoena in court, but that is the only protection they have.  Even if your confidentiality agreement doesn't have such a provision, you may want to let your ex-employer know about the subpoena beforehand so that it can take whatever action it deems appropriate to fight it, but, unless that subpoena is quashed or the party issuing the subpoena agrees to limit it, you have to testify, regardless of your contract with your ex-employer.  Of course, that doesn't mean that you don't have the right to object if the questions are inappropriate. I don't know if there is a specific Texas statute on point.