我正在使用jdbcTemplate批量插入2个表中。第一张表很简单，并且具有ID。第二个表有一个FK参考USER_ID，在插入之前我需要从表1中获取它。
假设我有这个：
Main Java Code（在这里我分为几批<= 1000）
for(int i = 0; i < totalEntries.size(); i++) {
// Add to Batch-Insert List; if list size ready for batch-insert, or if at the end, batch-persist & clear list
batchInsert.add(user);
if (batchInsert.size() == 1000 || i == totalEntries.size() - 1) {
// 1. Batch is ready, insert into Table 1
nativeBatchInsertUsers(jdbcTemplate, batchInsert);
// 2. Batch is ready, insert into Table 2
nativeBatchInsertStudyParticipants(jdbcTemplate, batchInsert);
// Reset list
batchInsert.clear();
}
}
批量插入表1的方法（注意，我在这里获得USERS_T的Seq Val）
private void nativeBatchInsertUsers(JdbcTemplate jdbcTemplate, final List<UsersT> batchInsert) {
String sqlInsert_USERS_T = "INSERT INTO PUBLIC.USERS_T (id, password, user_name) " +
"VALUES (nextval('users_t_id_seq'), ?, ? " +
")";
// Insert into USERS_T using overridden JdbcTemplate's Native-SQL batchUpdate() on the string "sqlInsert_USERS_T"
jdbcTemplate.batchUpdate(sqlInsert_USERS_T, new BatchPreparedStatementSetter() {
@Override
public int getBatchSize() {
return batchInsert.size();
}
@Override
public void setValues(PreparedStatement ps, int i) throws SQLException {
ps.setString(1, null);
ps.setString(2, batchInsert.get(i).getUsername());
// etc.
});
}
批量插入表2的方法
private void nativeBatchInsertStudyParticipants(JdbcTemplate jdbcTemplate, final List<UsersT> batchInsertUsers) {
String sqlInsert_STUDY_PARTICIPANTS_T =
"INSERT INTO PUBLIC.STUDY_PARTICIPANTS_T (id, study_id, subject_id, user_id) "
"VALUES (nextval('study_participants_t_id_seq'), ?, ?, ?
")";
// Insert into STUDY_PARTICIPANTS_T using overridden JdbcTemplate's Native-SQL batchUpdate() on the string "sqlInsert_USERS_T"
jdbcTemplate.batchUpdate(sqlInsert_STUDY_PARTICIPANTS_T, new BatchPreparedStatementSetter() {
@Override
public int getBatchSize() {
return batchInsert.size();
}
@Override
public void setValues(PreparedStatement ps, int i) throws SQLException {
// PROBLEM: For Param #4, USER_ID, need to get the USERS_T.ID from Batch-Insert #1
}
});
}
[当我进入第二批插入时，其中一列是返回到USERS_T.ID的FK，称为STUDY_PARTICIPANTS_T.USER_ID。我可以通过保持jdbcTemplate.batchUpdate()逻辑来获取它吗？
这是答案。
1]如果使用的是jdbcTemplate（Spring JDBC），则一种解决方案是预先保留自己的ID范围。然后自己为每行提供人工计算的ID。例如：
@Transactional(readOnly = false, rollbackFor = Exception.class)
public void doMultiTableInsert(List<String> entries) throws Exception {
// 1. Obtain current Sequence values
Integer currTable1SeqVal = table1DAO.getCurrentTable1SeqVal();
Integer currTable2SeqVal = table2DAO.getCurrentTable2SeqVal();
// 2. Immediately update the Sequences to the calculated final value (this reserves the ID range immediately)
table1DAO.setTable1SeqVal(currTable1SeqVal + entries.size());
table2DAO.setTable2SeqVal(currTable2SeqVal + entries.size());
for(int i = 0; i < entries.size(); i++) {
// Prepare Domain object...
UsersT user = new User();
user.setID(currTable1SeqVal + 1 + i); // Set ID manually
user.setCreatedDate(new Date());
// etc.
StudyParticipantsT sp = new StudyParticipantsT();
sp.setID(currTable2SeqVal + 1 + i); // Set ID manually
// etc.
user.setStudyParticipant(sp);
// Add to Batch-Insert List
batchInsertUsers.add(user);
// If list size ready for Batch-Insert (in this ex. 1000), or if at the end of all subjectIds, perform Batch Insert (both tables) and clear list
if (batchInsertUsers.size() == 1000 || i == subjectIds.size() - 1) {
// Part 1: Insert batch into USERS_T
nativeBatchInsertUsers(jdbcTemplate, batchInsertUsers);
// Part 2: Insert batch into STUDY_PARTICIPANTS_T
nativeBatchInsertStudyParticipants(jdbcTemplate, batchInsertUsers);
// Reset list
batchInsertUsers.clear();
}
}
}
然后再使用上面引用的Batch-Insert子方法：
1）
private void nativeBatchInsertUsers(JdbcTemplate jdbcTemplate, final List<UsersT> batchInsertUsers) {
String sqlInsert = "INSERT INTO PUBLIC.USERS_T (id, password, ... )"; // etc.
jdbcTemplate.batchUpdate(sqlInsert, new BatchPreparedStatementSetter() {
@Override
public int getBatchSize() {
return batchInsertUsers.size();
}
@Override
public void setValues(PreparedStatement ps, int i) throws SQLException {
ps.setInt(1, batchInsertUsers.get(i).getId()); // ID (provided by ourselves)
ps.setDate(2, batchInsertUsers.get(i).getCreatedDate());
//etc.
}
});
}
2）
private void nativeBatchInsertStudyParticipants(JdbcTemplate jdbcTemplate, final List<UsersT> batchInsertUsers) {
String sqlInsert = "INSERT INTO PUBLIC.STUDY_PARTICIPANTS_T (id, ... )"; // etc.
jdbcTemplate.batchUpdate(sqlInsert, new BatchPreparedStatementSetter() {
@Override
public int getBatchSize() {
return batchInsertUsers.size();
}
@Override
public void setValues(PreparedStatement ps, int i) throws SQLException {
ps.setInt(1, batchInsertUsers.get(i).getStudyParticipants().getId()); // ID (provided by ourselves)
//etc.
}
});
}
[有一些方法可以获取/设置序列值，例如在Postgres中，它是>
异常，SELECT last_value FROM users_t_id_seq; -- GET SEQ VAL SELECT setval('users_t_id_seq', 621938); -- SET SEQ VAL也请注意，所有内容都在
@Transactional下。如果该方法中有任何异常，则所有数据都会回滚（对于all
rollbackFor = Exception.class）。唯一不会回滚的是手动序列更新。但这没关系，序列可以有间隔。2）如果您愿意降低到PreparedStatement级别，则另一个解决方案是Statement.RETURN_GENERATED_KEYS：
PreparedStatement ps = con.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS)执行
ps后，ResultSet将按照创建它们的顺序包含您的ID。您可以遍历ResultSet并将ID存储在单独的列表中。
while (rs.next()) { generatedIDs.add(rs.getInt(1)); }[请记住，在这种情况下，您要负责自己的事务管理。您需要
conn.setAutoCommit(false);以使批次堆积而没有真正的持久性，然后单击conn.commit();/conn.rollback();。