当函数+列名中存在'`'防止关键字时处理出错。

[Anricx]

建议调整下处理结果列名策略，保证兼容性

Which version of Sharding-Jdbc do you using?

1.5.4.1

Expected behavior

NO ERROR!

Actual behavior

Caused by: org.apache.ibatis.executor.result.ResultMapException: Error attempting to get column 'COUNT(`status`)' from result set.  Cause: java.lang.NullPointerException
	at org.apache.ibatis.type.BaseTypeHandler.getResult(BaseTypeHandler.java:68)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createPrimitiveResultObject(DefaultResultSetHandler.java:720)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createResultObject(DefaultResultSetHandler.java:607)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.createResultObject(DefaultResultSetHandler.java:586)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.getRowValue(DefaultResultSetHandler.java:388)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValuesForSimpleResultMap(DefaultResultSetHandler.java:347)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleRowValues(DefaultResultSetHandler.java:322)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSet(DefaultResultSetHandler.java:295)
	at org.apache.ibatis.executor.resultset.DefaultResultSetHandler.handleResultSets(DefaultResultSetHandler.java:192)
	at org.apache.ibatis.executor.statement.PreparedStatementHandler.query(PreparedStatementHandler.java:64)
	at org.apache.ibatis.executor.statement.RoutingStatementHandler.query(RoutingStatementHandler.java:79)
	at org.apache.ibatis.executor.SimpleExecutor.doQuery(SimpleExecutor.java:63)
	at org.apache.ibatis.executor.BaseExecutor.queryFromDatabase(BaseExecutor.java:324)
	at org.apache.ibatis.executor.BaseExecutor.query(BaseExecutor.java:156)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:109)
	at org.apache.ibatis.executor.CachingExecutor.query(CachingExecutor.java:83)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:148)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectList(DefaultSqlSession.java:141)
	at org.apache.ibatis.session.defaults.DefaultSqlSession.selectOne(DefaultSqlSession.java:77)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.mybatis.spring.SqlSessionTemplate$SqlSessionInterceptor.invoke(SqlSessionTemplate.java:433)
	... 17 more
Caused by: java.lang.NullPointerException
	at com.dangdang.ddframe.rdb.sharding.merger.common.AbstractMemoryResultSetMerger.getValue(AbstractMemoryResultSetMerger.java:64)
	at com.dangdang.ddframe.rdb.sharding.jdbc.core.resultset.ShardingResultSet.getInt(ShardingResultSet.java:100)
	at org.apache.ibatis.type.IntegerTypeHandler.getNullableResult(IntegerTypeHandler.java:37)
	at org.apache.ibatis.type.IntegerTypeHandler.getNullableResult(IntegerTypeHandler.java:26)
	at org.apache.ibatis.type.BaseTypeHandler.getResult(BaseTypeHandler.java:66)
	... 40 more

Steps to reproduce the behavior

数据库层添加统计方法不为结果添加别名

    <select id="count" resultType="java.lang.Integer">
        SELECT
         COUNT(`status`)
        FROM t_order
    </select>

Please provide the reproduce example codes (such as github link) if possible.

private Map<String, Integer> getColumnLabelIndexMap(ResultSet resultSet) throws SQLException {
        ResultSetMetaData resultSetMetaData = resultSet.getMetaData();
        Map<String, Integer> result = new TreeMap(String.CASE_INSENSITIVE_ORDER);

        for(int i = 1; i <= resultSetMetaData.getColumnCount(); ++i) {
            result.put(SQLUtil.getExactlyValue(resultSetMetaData.getColumnLabel(i)), i);
        }

        return result;
    }

[haocao]

请在github上提供完整重现DEMO，以便跟进调试。

[Anricx]

sharding-jdbc-example-mybatis.zip

请参考。

[Anricx]

由于底层解析ResultSetMetaData时将查询中的‘’符号去掉了，所以在this.labelAndIndexMap中世纪存储的列名变成了 COUNT(status) , 实际在AbstractMemoryResultSetMerger中getValue方法在从this.labelAndIndexMap取对应列时使用的列名为查询SQL中的 COUNT(status`) 导致未找到列触发了错误。

1. 当然SQL应该这里加上别名，就不会有这个错误。
2. 我以为最佳的解决方案或许是在SQLUtil.getExactlyValue中如果是聚合函数中的是否就可以考虑不要移除特殊符号？尽量在最终将结果集返回最终字段才做转换。

[terrymanu]

fixed at 2.0.0.m1