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Query Builders
Overview
A function that builds part of a query is called a builder.
All builder functions are defined in org.komapper.core.dsl.query.
where
The where function builds a Where declaration.
val salaryWhere = where {
e.salary greater BigDecimal(1_000)
}
val query: Query<List<Employee>> = QueryDsl.from(e).where(salaryWhere)
on
The on function builds a On declaration.
val departmentIdOn = on {
e.departmentId eq d.departmentId
}
val query: Query<List<Employee>> = QueryDsl.from(e).innerJoin(d, departmentIdOn)
having
The having function builds a Having declaration.
val countHaving = having {
count() greater 3
}
val query: Query<List<Int?>> = QueryDsl.from(e)
.groupBy(e.departmentId)
.having(countHaving)
.select(e.departmentId)
set
The set function builds an Assignment declaration.
val addressAssignment = set(a) {
a.street eq "STREET 16"
}
val query: Query<Int> = QueryDsl.update(a).set(addressAssignment).where {
a.addressId eq 1
}
values
The values function builds an Assignment declaration.
val addressAssignment = values(a) {
a.street eq "STREET 16"
}
val query: Query<Pair<Int, Int?>> = QueryDsl.insert(a).values(addressAssignment)
join
The join function builds a Join element.
The Join element can be passed to the innerJoin or leftJoin functions:
val departmentJoin = join(d) {
e.departmentId eq d.departmentId
}
val query1: Query<List<Employee>> = QueryDsl.from(e).innerJoin(departmentJoin)
val query2: Query<List<Employee>> = QueryDsl.from(e).leftJoin(departmentJoin)
groupBy
The groupBy function builds a list of column expressions.
val groupByDepartmentId = groupBy(e.departmentId)
val query: Query<List<Int?>> = QueryDsl.from(e)
.groupBy(groupByDepartmentId)
.having {
count() greater 3
}
.select(e.departmentId)
orderBy
The orderBy function builds a list of sort expressions.
val orderBySalaryAndNo = orderBy(e.salary, e.employeeNo)
val query: Query<List<Employee>> = QueryDsl.from(e).orderBy(orderBySalaryAndNo)