Query criteria for matching 3 of 6 fields - kotlin

Question

I would like to select rows in the Corda (M14) database with a criteria that matches at least 3 of 6 fields and sort these results by matching fields.
Here is the SQL syntax to select fields:
WHERE (field1 = ?) + (field2 = ?) + (... = ?) > 3
and to order it:
ORDER BY ((field1 = ?) + (field2 = ?) + (... = ?)) DESC
Another way of doing it :
SELECT *, ((field1 = #inputFirst) + (field2 = #inputLast)) as Matches
FROM mytable
HAVING Matches > 1
ORDER BY Matches DESC
I started to create the criteria:
vaultCriteria
.or(QueryCriteria.VaultCustomQueryCriteria(field1))
.or(QueryCriteria.VaultCustomQueryCriteria(field12))
.or(QueryCriteria.VaultCustomQueryCriteria(field3))
But I am stuck now on how to GROUP theses results by fields' matching number and SORT these, any ideas ?
Thank you,
Loup

Answer 1

I haven't tested how far it's possible to take the API, but I've had success (on current Master) by writing custom SQL - e.g.
val session = services.jdbcSession()
val consensusQuery = """
SELECT COUNT(*) - COUNT(NULLIF(factObject, ?)), COUNT(*)
FROM submission_states
WHERE factSubject = ? AND factPredicate = ?
"""
val consensusStatement = session.prepareStatement(consensusQuery)
consensusStatement.setString(1, factConsensusQuery.factObject)
consensusStatement.setString(2, factConsensusQuery.factSubject)
consensusStatement.setString(3, factConsensusQuery.factPredicate)
log.info("SQL to execute: " + consensusStatement.toString())
val rs = consensusStatement.executeQuery()

Answer 2

For M14 release you have 2 options:
1) Get a jdbcSession directly from the DatabaseTransactionManager:
val jdbcSession1 = DatabaseTransactionManager.current().connection
2) Get a jdbcSession indirectly from a RequeryConfiguration object:
val jdbcSession2 = RequeryConfiguration(<dataSourceProperties>).jdbcSession()
where <dataSourceProperties> looks something like this:
private fun makePersistentDataSourceProperties(): Properties {
val props = Properties()
props.setProperty("dataSourceClassName", "org.h2.jdbcx.JdbcDataSource")
props.setProperty("dataSource.url", "jdbc:h2:~/test/vault_query_persistence;DB_CLOSE_ON_EXIT=TRUE")
props.setProperty("dataSource.user", "sa")
props.setProperty("dataSource.password", "")
return props
}

Answer 3

For advanced custom SQL queries it is recommended you use a standard JDBCSession, obtainable from the ServiceHub.
Please see https://docs.corda.net/head/api-persistence.html?highlight=jdbcsession