1. A sequence online analytical processing (S-OLAP) system for analysing an event database storing events, each event consisting of at least one dimension and measure;, the system comprising: a sequence cuboid (S-cuboid) builder to build an S-cuboid, the S-cuboid defining a logical view of the sequence data at a predetermined degree of summarization; wherein the S-cuboid built by the S-cuboid builder is specified by: a WHERE clause to select events of interest; a CLUSTER BY clause to specify events that are elements of a sequence to be clustered together; a SEQUENCE BY clause to form a sequence from a cluster of events; a SEQUENCE GROUP BY clause to group sequences whose events share the same dimension values and form a sequence group; a CUBOID BY clause to specify the logical view of the sequence data; and at least one aggregation function to be applied to the sequences in each S-cuboid cell.