Batch update via temp table [Question]

Hey Everybody, I’m trying to implement batch upsert logic for Postgres. As Postgres doesn’t support Merge statement yet (https://github.com/linq2db/linq2db/issues/892), I have to stick with temporary table to hold updated records.

The question is how can I write the following query via linq expressions to update existing records in the original table in single query?

UPDATE origin_table AS record 
	SET column1 = temp_record.column1,
    	column2 = temp_record.column2,
    	column3 = temp_record.column3
FROM temp_table AS temp_record
WHERE record.id = temp_record.id

Is it possible with linq2db ? Currently I’m executing this as raw query like:

var result = db.Query<dynamic>(
                    @"UPDATE customers AS record 
                        SET code = temp_record.code,
                            tenant_id = temp_record.tenant_id
                        FROM temp_customers AS temp_record
                        WHERE record.id = temp_record.id"
                ).ToList();

Is there better way to do this ?

[sdanyliv]

This sample also should work, just ensure that first recordset in query is table that needs to be updated:

using (var tempTable = db.CreateTempTable(tempTableName, customers))
{
	var recordsToUpdate =
		from c in db.GetTable<customer>()
		from t in tempTable.InnerJoin(t => t.id == c.id)
		select new {c, t};

	recordsToUpdate
		.Set(v => v.c.code,      v => v.t.code)
		.Set(v => v.c.tenant_id, v => v.t.tenant_id)
		.Update();
}

[anirujogi]

Using temp table in query string is not working in SQL Server too. Is there a way we can access temp table in raw sql? Getting object not found error.

using (var tempTable = db.CreateTempTable(tempTableName, customers)) { var recordsToUpdate = from c in db.GetTable<customer>() from t in tempTable.InnerJoin(t => t.id == c.id) select new {c, t};

var result = db.Query<dynamic>(
                @"UPDATE customers AS record 
                    SET code = temp_record.code,
                        tenant_id = temp_record.tenant_id
                    FROM temp_customers AS temp_record
                    WHERE record.id = temp_record.id"
            ).ToList();

}