Mybatis update delete 操作的返回值

insert，返回值是：新插入行的主键（primary key）；需要包含<selectKey>语句，才会返回主键，否则返回值为null。
update/delete，返回值是：更新或删除的行数；无需指明resultClass；但如果有约束异常而删除失败，只能去捕捉异常。
queryForObject，返回的是：一个实例对象或null；需要包含<select>语句，并且指明resultMap；
queryForList，返回的是：实例对象的列表；需要包含<select>语句，并且指明resultMap；

关于ibatis的接口，参见其源码（com\ibatis\sqlmap\client\SqlMapExecutor.java）:

/*
*  Copyright 2004 Clinton Begin
*
*  Licensed under the Apache License, Version 2.0 (the "License");
*  you may not use this file except in compliance with the License.
*  You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0 *
*  Unless required by applicable law or agreed to in writing, software
*  distributed under the License is distributed on an "AS IS" BASIS,
*  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
*  See the License for the specific language governing permissions and
*  limitations under the License.
*/
package com.ibatis.sqlmap.client;

import com.ibatis.common.util.PaginatedList;
import com.ibatis.sqlmap.client.event.RowHandler;
import com.ibatis.sqlmap.engine.execution.BatchException;

import java.sql.SQLException;
import java.util.List;
import java.util.Map;

/**
* This interface declares all methods involved with executing statements
* and batches for an SQL Map.
*
* @see SqlMapSession
* @see SqlMapClient
*/
public interface SqlMapExecutor {

/**
* Executes a mapped SQL INSERT statement.
* Insert is a bit different from other update methods, as it
* provides facilities for returning the primary key of the
* newly inserted row (rather than the effected rows).  This
* functionality is of course optional.
* <p/>
* The parameter object is generally used to supply the input
* data for the INSERT values.
*
* @param id              The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @return The primary key of the newly inserted row.  This might be automatically
*         generated by the RDBMS, or selected from a sequence table or other source.
* @throws java.sql.SQLException If an error occurs.
*/
Object insert(String id, Object parameterObject) throws SQLException;

/**
* Executes a mapped SQL INSERT statement.
* Insert is a bit different from other update methods, as it
* provides facilities for returning the primary key of the
* newly inserted row (rather than the effected rows).  This
* functionality is of course optional.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id              The name of the statement to execute.
* @return The primary key of the newly inserted row.  This might be automatically
*         generated by the RDBMS, or selected from a sequence table or other source.
* @throws java.sql.SQLException If an error occurs.
*/
Object insert(String id) throws SQLException;

/**
* Executes a mapped SQL UPDATE statement.
* Update can also be used for any other update statement type,
* such as inserts and deletes.  Update returns the number of
* rows effected.
* <p/>
* The parameter object is generally used to supply the input
* data for the UPD
3ff0
ATE values as well as the WHERE clause parameter(s).
*
* @param id              The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @return The number of rows effected.
* @throws java.sql.SQLException If an error occurs.
*/
int update(String id, Object parameterObject) throws SQLException;

/**
* Executes a mapped SQL UPDATE statement.
* Update can also be used for any other update statement type,
* such as inserts and deletes.  Update returns the number of
* rows effected.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id              The name of the statement to execute.
* @return The number of rows effected.
* @throws java.sql.SQLException If an error occurs.
*/
int update(String id) throws SQLException;

/**
* Executes a mapped SQL DELETE statement.
* Delete returns the number of rows effected.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the DELETE statement.
*
* @param id              The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @return The number of rows effected.
* @throws java.sql.SQLException If an error occurs.
*/
int delete(String id, Object parameterObject) throws SQLException;

/**
* Executes a mapped SQL DELETE statement.
* Delete returns the number of rows effected.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id              The name of the statement to execute.
* @return The number of rows effected.
* @throws java.sql.SQLException If an error occurs.
*/
int delete(String id) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a single object instance.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id              The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @return The single result object populated with the result set data,
*         or null if no result was found
* @throws java.sql.SQLException If more than one result was found, or if any other error occurs.
*/
Object queryForObject(String id, Object parameterObject) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a single object instance.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id              The name of the statement to execute.
* @return The single result object populated with the result set data,
*         or null if no result was found
* @throws java.sql.SQLException If more than one result was found, or if any other error occurs.
*/
Object queryForObject(String id) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* the supplied result object.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id              The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @param resultObject    The result object instance that should be populated with result data.
* @return The single result object as supplied by the resultObject parameter, populated with the result set data,
*         or null if no result was found
* @throws java.sql.SQLException If more than one result was found, or if any other error occurs.
*/
Object queryForObject(String id, Object parameterObject, Object resultObject) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id              The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @return A List of result objects.
* @throws java.sql.SQLException If an error occurs.
*/
List queryForList(String id, Object parameterObject) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id              The name of the statement to execute.
* @return A List of result objects.
* @throws java.sql.SQLException If an error occurs.
*/
List queryForList(String id) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects within a certain range.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id              The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @param skip            The number of results to ignore.
* @param max             The maximum number of results to return.
* @return A List of result objects.
* @throws java.sql.SQLException If an error occurs.
*/
List queryForList(String id, Object parameterObject, int skip, int max) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects within a certain range.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id              The name of the statement to execute.
* @param skip            The number of results to ignore.
* @param max             The maximum number of results to return.
* @return A List of result objects.
* @throws java.sql.SQLException If an error occurs.
*/
List queryForList(String id, int skip, int max) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns a number of
* result objects that will be handled one at a time by a
* RowHandler.
* <p/>
* This is generally a good approach to take when dealing with large sets
* of records (i.e. hundreds, thousands...) that need to be processed without
* eating up all of the system resources.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id              The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @param rowHandler      A RowHandler instance
* @throws java.sql.SQLException If an error occurs.
*/
void queryWithRowHandler(String id, Object parameterObject, RowHandler rowHandler) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns a number of
* result objects that will be handled one at a time by a
* RowHandler.
* <p/>
* This is generally a good approach to take when dealing with large sets
* of records (i.e. hundreds, thousands...) that need to be processed without
* eating up all of the system resources.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id              The name of the statement to execute.
* @param rowHandler      A RowHandler instance
* @throws java.sql.SQLException If an error occurs.
*/
void queryWithRowHandler(String id, RowHandler rowHandler) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects a page at a time.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id              The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @param pageSize        The maximum number of result objects each page can hold.
* @return A PaginatedList of result objects.
* @throws java.sql.SQLException If an error occurs.
* @deprecated All paginated list features have been deprecated
*/
PaginatedList queryForPaginatedList(String id, Object parameterObject, int pageSize) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects a page at a time.
* <p/>
* This overload assumes no parameter is needed.
*
* @param id              The name of the statement to execute.
* @param pageSize        The maximum number of result objects each page can hold.
* @return A PaginatedList of result objects.
* @throws java.sql.SQLException If an error occurs.
* @deprecated All paginated list features have been deprecated
*/
PaginatedList queryForPaginatedList(String id, int pageSize) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects that will be keyed into a Map.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id              The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @param keyProp         The property to be used as the key in the Map.
* @return A Map keyed by keyProp with values being the result object instance.
* @throws java.sql.SQLException If an error occurs.
*/
Map queryForMap(String id, Object parameterObject, String keyProp) throws SQLException;

/**
* Executes a mapped SQL SELECT statement that returns data to populate
* a number of result objects from which one property will be keyed into a Map.
* <p/>
* The parameter object is generally used to supply the input
* data for the WHERE clause parameter(s) of the SELECT statement.
*
* @param id              The name of the statement to execute.
* @param parameterObject The parameter object (e.g. JavaBean, Map, XML etc.).
* @param keyProp         The property to be used as the key in the Map.
* @param valueProp       The property to be used as the value in the Map.
* @return A Map keyed by keyProp with values of valueProp.
* @throws java.sql.SQLException If an error occurs.
*/
Map queryForMap(String id, Object parameterObject, String keyProp, String valueProp) throws SQLException;

/**
* Starts a batch in which update statements will be cached before being sent to
* the database all at once. This can improve overall performance of updates update
* when dealing with numerous updates (e.g. inserting 1:M related data).
*
* @throws java.sql.SQLException If the batch could not be started.
*/
void startBatch() throws SQLException;

/**
* Executes (flushes) all statements currently batched.
*
* @return the number of rows updated in the batch
* @throws java.sql.SQLException If the batch could not be executed or if any of the statements
*                               fails.
*/
int executeBatch() throws SQLException;

/**
* Executes (flushes) all statements currently batched.
*
* @return a List of BatchResult objects.  There will be one element in the
*  list for each sub-batch executed.  A sub-batch is created by adding a statement
*  to the batch that does not equal the prior statement.
* @throws SQLException if a database access error occurs, or the drive
*   does not support batch statements
* @throws BatchException if the driver throws BatchUpdateException
* @see com.ibatis.sqlmap.engine.execution.BatchException
*/
List executeBatchDetailed() throws SQLException, BatchException;
}