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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def execute(self, conn, migration_url="", migration_input="", create_by="", migration_request_id="", oldest= False, transaction=False):
 """ Lists all requests if pattern is not provided. """

        sql = self.sql
        binds = {}
	if migration_request_id:
	    sql += " WHERE MR.MIGRATION_REQUEST_ID=:migration_request_id"
	    binds['migration_request_id']=migration_request_id
        elif oldest:
            #FIXME: Need to write the sql.YG
            #current_date = dbsUtils().getTime()
            #we require waiting time for 
            #retry_count=0 is 1 minutes
            #retry_count=1 is 2 minutes
            #retyr_count=2 is 4 minutes

            sql += """
                       WHERE MR.MIGRATION_STATUS=0 
                       or (MR.migration_status=3 and MR.retry_count=0 and MR.last_modification_date <= :current_date-60)    
                       or (MR.migration_status=3 and MR.retry_count=1 and MR.last_modification_date <= :current_date-120)  
                       or (MR.migration_status=3 and MR.retry_count=2 and MR.last_modification_date <= :current_date-240)
                       ORDER BY MR.creation_date
                   """ 
            binds['current_date'] = dbsUtils().getTime()
            #print "time= " + str(binds['current_date'])
        else:    
	    if  migration_url or migration_input or create_by:
		sql += " WHERE "
	    if migration_url:
		sql += " MR.MIGRATION_URL=:migration_url"
		binds['migration_url']=migration_url
	    if  migration_input:
		if migration_url:
		    sql += " AND "
		op = ("=", "like")["%" in migration_input]
		sql += " MR.MIGRATION_INPUT %s :migration_input" % op
		binds['migration_input']=migration_input
	    if create_by:
		if  migration_url or migration_input:
		    sql += " AND "
		sql += " MR.CREATE_BY=:create_by" %create_by
		binds['create_by']=create_by
	cursors = self.dbi.processData(sql, binds, conn, transaction, returnCursor=True)
        result = []
        for c in cursors:
            result.extend(self.formatCursor(c, size=100))
        return result