Working with Sequence

A sequence is a database object that automatically generates integer values in sequential order. It is particularly useful in generating unique identifiers and primary keys.

Define a sequence

To define a sequence in Exposed, use the Sequence class:

val myseq = Sequence("my_sequence") // my_sequence is the sequence name.

Several parameters can be specified to control the properties of the sequence:

            private val myseq = Sequence(
                name = "my_sequence",
                startWith = 4,
                incrementBy = 2,
                minValue = 1,
                maxValue = 10,
                cycle = true,
                cache = 20
            )
        

Create a sequence

To create a sequence, use the createSequence() method provided by SchemaUtils:

SchemaUtils.createSequence(myseq)

Drop a sequence

To drop a sequence, use the dropSequence() method provided by SchemaUtils:

SchemaUtils.dropSequence(myseq)

Access the next value

You can access the next value in a sequence by using the nextIntVal() function:

            val nextVal = myseq.nextIntVal()
            val id = StarWarsFilms.insertAndGetId {
                it[id] = nextVal
                it[name] = "The Last Jedi"
                it[sequelId] = 8
                it[director] = "Rian Johnson"
            }
        

val firstValue = StarWarsFilms.select(nextVal).single()[nextVal]

Last modified: 25 September 2024