如何从jOOQ查询中删除子句（order by）

Question

Is possible to remove a clause (the order by clause in my case) from a dynamically constructed query in jOOQ.

Suppose that after creating the query:

DSLContext create = DSL.using(SQLDialect.POSTGRES);
SelectQuery<Record> query = create.select().from("myTable").where("fk = 1").orderBy(DSL.field("pk")).getQuery();
System.out.println(query.getSQL());
// select * from myTable where (fk = 1) order by pk asc

I want to change the order by clause or remove it to get only

select * from myTable where (fk = 1)

Is possible make this with jOOQ?. If is not possible and anyone knows a query builder library that allows this will be also welcome.

Answer 1

This currently cannot be done through the public API. In a future jOOQ 4.0, there might be a cleaner separation of the DSL API and the Model API , where such a model API would allow you to freely manipulate all your query parts, including removing objects again from SELECT clauses.

Right now, you have at least two options to implement dynamic SQL:

1. Don't add the ORDER BY clause until you know whether you need it:

    SelectQuery<?> select = create .select() .from("myTable") .where("fk = 1") .getQuery(); if (someCondition) select.addOrderBy(DSL.field("pk")); 

   Alternative piece of logic:

    List<SortField<?>> orderBy = new ArrayList<>(); if (someCondition) orderBy.add(DSL.field("pk").asc()); create.select() .from("myTable") .where("fk = 1") .orderBy(orderBy); 

2. Post-process / transform your query using an ExecuteListener or a VisitListener . This is more of a workaround in edge-cases, though.

In your particular case, you should probably go with option 1. Another, more functional approach to tackling dynamic SQL generation is documented here .