do we a shorthand to get a count of number of rows are present in db with respect to a where clause in r2bc

Question

"Is there any short hand to no .of rows in a database against a where condition" if we have a criteria definition present against which want number of rows present in database. is is any function in r2dbc that give that?

As it is about executing SQL, what is wrong with doing a `SELECT COUNT(*) FROM YOUR_TABLE WHERE ` why would that be different here? — M. Deinum, Jul 07 '20 at 12:25
The condition that gets build up is dynamic, it depends on fields that are populated in my object of criteria definition — DEVYANI SETHI, Jul 07 '20 at 12:49
So? What prevents you from executing a dynamic query? If you can execute a query you can also execute the count query. — M. Deinum, Jul 07 '20 at 12:55
How can we create a query from CriteriaObject the method execute() requires a string — DEVYANI SETHI, Jul 08 '20 at 14:43
like we have select(), insert() methods in r2dbc so do we have a method for count as well — DEVYANI SETHI, Jul 08 '20 at 14:44
what do you think `select` does. How is a `select count(*)` different from `select foo, bar from baz`. It is just a select statement. — M. Deinum, Jul 08 '20 at 14:47
@DEVYANISETHI It's been quite a while since you asked this question. Any updates from your side? Did you try out the answer I had provided? — Abhinaba Chakraborty, Jul 22 '20 at 16:35

score 2 · Answer 1 · answered Jul 18 '20 at 20:06

You can have something like this:

@Repository
public class MyCustomRepositoryImpl {

  private final R2dbcEntityTemplate r2dbcEntityTemplate;

  @Autowired
  public MyCustomRepositoryImpl(DatabaseClient databaseClient) {
    this.r2dbcEntityTemplate = new R2dbcEntityTemplate(databaseClient);
  }

  public Mono<Long> getCountOfAllRows() {
    return r2dbcEntityTemplate.count(query(Criteria.empty()),MyEntity.class);
  }

  public Mono<Long> getCountOfRowsForACondition(String myVal) {
    return r2dbcEntityTemplate.select(query(Criteria.where("mycolumn").is(myVal)),MyEntity.class);
  }
}

Note here query is the static method of org.springframework.data.relational.core.query.Query

do we a shorthand to get a count of number of rows are present in db with respect to a where clause in r2bc

1 Answers1