class Test {

    private static final String PROJECT_INFO_FOR_USER ="select PROJECT_ID as PROJECT_NO, NAME as PROJECT_NAME from PROJECT_DIM where PROJECT_ID IN (?)"

    private def getProjectList(def caseResult) {
        def projectList = ""
        caseResult.each { projno ->
            if (projectList.length() == 0) {
                projectList = "'${projno.project_no}',"
            } else {
                if (projectList.indexOf(projno.project_no) == -1)
                    projectList+="'${projno.project_no}',"
            }
        }
        projectList = projectList.substring(0, projectList.length() - 1)
        return projectList
    }

    private process() {
        def db = [url: "jdbc:oracle:thin:@x.xx.xx.xx:1521:ORCL",
                  user: 'xxxx', password: 'xxxx', driver: 'oracle.jdbc.pool.OracleDataSource']
        def sql = Sql.newInstance(db.url, db.user, db.password, db.driver)
        println "DB connection ready"

        def caseResult = [['project_no':'x-xxxx', 'case_nos':['12344'], 'updated_on':'1485335172'], ['project_no':'y-yyyy', 'case_nos':['56789'], 'updated_on':1490359241]]
        def projectList = "x-xxxx"
        def params = getProjectList(caseResult)
        def result = sql.rows(PROJECT_INFO_FOR_USER, params).collect {          // If I replace params with projectList then <b>result</b> is assigned a row from oracle database
            it as Map
        }
        println result
    }

    public static void main(String[] args) {
        Test t = new Test()
        t.process()
    }
}

DB connection ready
[]

DB connection ready
[[PROJECT_NO:x-xxxx, PROJECT_NAME:Xonions, Inc.]]