26-JDBC

Question 1

What is the basic exception if there’s anything wrong with JDBC?

Answer 1

SQLException

Question 2

Arguments in JdbcTemplate.query to query and map row to the entity?

Answer 2

JdbcTemplate.query(String, RowMapper)

T RowMapper.mapRow(ResultSet, int row) throws SQL Exception {}

Question 3

How to create JdbcTemplate?

Answer 3

new JdbcTemplate(DataSource)

Question 4

Can JdbcTemplate be shared among threads?

Answer 4

Yes, it’s thread-safe

Question 5

Using JdbcTemplate to count the number of users?

Answer 5

jdbcTemplate.queryForObject(“…”, Integer.class)

Question 6

Using JdbcTemplate to update age by user-id

Answer 6

jdbcTemplate.update(“UPDATE … age = ? WHERE id = ?”, age, id)

Question 7

JdbcTemplate.queryForList vs. JdbcTemplate.queryForMap

Answer 7

queryForMap: expecting a single row
queryForList: expecting multiple rows, each is a Map

Question 8

What exception does the RowMapper.mapRow for JdbcTemplate.query returns?

Answer 8

SQLException

Question 9

With JdbcTemplate, how to handle the result set manually?

Answer 9

jdbcTemplate.query(String, ResultSetExtractor)

ResultSetExtractor.extracData(ResultSet) throws SQLException, DataAccessException

Question 10

JdbcTemplate: RowCallbackHandler vs. RowMapper

Answer 10

RowCallbackHandler.processRow(ResultSet) won’t return record (i.e. return void)
RowMapper.mapRow(ResultSet, row) returns record

Question 11

What kind of exception does Spring throw?

Answer 11

Spring always throws Runtime (unchecked) Exceptions

Question 12

What exception class does Spring create to replace SQLException?

Answer 12

DataAccessException
+ Hides whether you are using JPA, Hibernate, JDBC …
+ Consistent across all supported Data Access technologies