sqlMapClientTemplate：空数组参数导致 BadSqlGrammarException

Question

Java版本为Java8，MySQL版本为5.6

我在运行这一行JavaSpring:

private SqlMapClientTemplate template = getSqlMapClientTemplate();
List<String> topicList = licReq.getTopicCategories();
template.queryForList("get_topic_ids_from_list", topicList);

其中“get_topic_ids_from_list”在 pom.xml 文件中按以下方式定义：

<select id="get_topic_ids_from_list" parameterClass="list" resultClass="Long">
  select id from topic_categories where topic_name in
    <iterate open="(" close=")" conjunction=",">
        #[]#
    </iterate>
</select>

当参数topicList不为空时，正常。但是，如果 topicList 为空，则会导致以下错误：

org.springframework.jdbc.BadSqlGrammarException: SqlMapClient operation; bad SQL grammar []; nested exception is com.ibatis.common.jdbc.exception.NestedSQLException:
--- The error occurred while applying a parameter map.
--- Check the get_topic_ids_from_list-InlineParameterMap.
--- Check the statement (query failed).
--- Cause: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1

有没有更好的方法来定义 pom.xml 中的“get_topic_ids_from_list”查询，以便它只是 returns 空数组（long 类型），或者如果空数组情况的语句？

Answer 1

查询前需要确保topicList不为空

List<String> topicList = licReq.getTopicCategories();

if (topicList.size() > 0) {
    template.queryForList("get_topic_ids_from_list", topicList);
} else {
    // return empty result
}

sqlMapClientTemplate：空数组参数导致 BadSqlGrammarException

sqlMapClientTemplate: empty array parameter causes BadSqlGrammarException

java

mysql

spring

jdbc