Add support for accessing LastInsertId and RowsAffected for all statements in a batch #1261
Description
Issue description
When calling Exec() with multiple statements, we'd like to be able to access LastInsertId and RowsAffected for all statements, not just the last one.
The motivating use case is performing batches of UPDATE statements with minimal roundtrips, while determining the result of each separately.
Example code
My PR to implement this exposes additional methods on mysqlResult, which is accessible when querying with sql.Conn.Raw() using a new mysql.Result interface:
conn, _ := db.Conn(ctx)
conn.Raw(func(conn interface{}) error {
ex := conn.(driver.Execer)
res, _ := ex.Exec(`
UPDATE point SET x = 1 WHERE y = 2;
UPDATE point SET x = 2 WHERE y = 3;
`, nil)
log.Print(res.(mysql.Result).AllRowsAffected()) // eg. {5, 10}
})It looks like exposing the same functionality for sql.Stmt isn't possible yet, since it has no equivalent to sql.Conn.Raw().