我正在使用iBatis / Java和Postgres 8.3。
当我在ibatis中插入时,我需要返回id
我用下表来描述我的问题:
CREATE TABLE sometable ( id serial NOT NULL, somefield VARCHAR(10) );
通过运行create语句自动生成序列sometable_id_seq
。
目前我使用以下sql map:
<insert id="insertValue" parameterClass="string" >
INSERT INTO sometable ( somefield ) VALUES ( #value# );
<selectKey keyProperty="id" resultClass="int">
SELECT last_value AS id FROM sometable_id_seq
</selectKey>
</insert>
这似乎是ibatis检索新插入的id的方法。 Ibatis首先运行INSERT语句,然后询问序列的最后一个id 我怀疑这将适用于许多并发插入。
这会引起问题吗?就像返回错误插入的id一样?
(另请参阅我关于how to get ibatis to use the INSERT .. RETURING .. statements的相关问题)
答案 0 :(得分:2)
这绝对是错误的。使用:
select currval('sometable_id_seq')
或更好:
INSERT INTO sometable ( somefield ) VALUES ( #value# ) returning id
将返回您插入的ID。
答案 1 :(得分:0)
这是一个简单的例子:
<statement id="addObject"
parameterClass="test.Object"
resultClass="int">
INSERT INTO objects(expression, meta, title,
usersid)
VALUES (#expression#, #meta#, #title#, #usersId#)
RETURNING id
</statement>
在Java代码中:
Integer id = (Integer) executor.queryForObject("addObject", object);
object.setId(id);
答案 2 :(得分:0)
我有另一个想法。 ibatis
调用insert方法委托Class:com.ibatis.sqlmap.engine.impl.SqlMapExecutorDelegate,with the code
:
try {
trans = autoStartTransaction(sessionScope, autoStart, trans);
SelectKeyStatement selectKeyStatement = null;
if (ms instanceof InsertStatement) {
selectKeyStatement = ((InsertStatement) ms).getSelectKeyStatement();
}
// Here we get the old value for the key property. We'll want it later if for some reason the
// insert fails.
Object oldKeyValue = null;
String keyProperty = null;
boolean resetKeyValueOnFailure = false;
if (selectKeyStatement != null && !selectKeyStatement.isRunAfterSQL()) {
keyProperty = selectKeyStatement.getKeyProperty();
oldKeyValue = PROBE.getObject(param, keyProperty);
generatedKey = executeSelectKey(sessionScope, trans, ms, param);
resetKeyValueOnFailure = true;
}
StatementScope statementScope = beginStatementScope(sessionScope, ms);
try {
ms.executeUpdate(statementScope, trans, param);
}catch (SQLException e){
// uh-oh, the insert failed, so if we set the reset flag earlier, we'll put the old value
// back...
if(resetKeyValueOnFailure) PROBE.setObject(param, keyProperty, oldKeyValue);
// ...and still throw the exception.
throw e;
} finally {
endStatementScope(statementScope);
}
if (selectKeyStatement != null && selectKeyStatement.isRunAfterSQL()) {
generatedKey = executeSelectKey(sessionScope, trans, ms, param);
}
autoCommitTransaction(sessionScope, autoStart);
} finally {
autoEndTransaction(sessionScope, autoStart);
}
您可以看到插入和选择运算符位于事务中。所以我认为插入方法没有一致性问题。