iBatis习惯用的16条SQL语句

2024-03-10 15:08:05 195

iBatis简介：

iBatis是apache的一个开源项目，一个O/RMapping解决方案，iBatis最大的特点就是小巧，上手很快。如果不需要太多复杂的功能，iBatis是能够满足你的要求又足够灵活的最简单的解决方案，现在的iBatis已经改名为Mybatis了。

官网为：http://www.mybatis.org/

1.输入参数为单个值

<deleteid="com.fashionfree.stat.accesslog.deleteMemberAccessLogsBefore"
parameterClass="long">
deletefrom
MemberAccessLog
where
accessTimestamp=#value#
</delete>
<deleteid="com.fashionfree.stat.accesslog.deleteMemberAccessLogsBefore"
parameterClass="long">
deletefrom
MemberAccessLog
where
accessTimestamp=#value#
</delete>

2.输入参数为一个对象

<insertid="com.fashionfree.stat.accesslog.MemberAccessLog.insert"
parameterClass="com.fashionfree.stat.accesslog.model.MemberAccessLog>
insertintoMemberAccessLog
(
accessLogId,memberId,clientIP,
httpMethod,actionId,requestURL,
accessTimestamp,extend1,extend2,
extend3
)
values
(
#accessLogId#,#memberId#,
#clientIP#,#httpMethod#,
#actionId#,#requestURL#,
#accessTimestamp#,#extend1#,
#extend2#,#extend3#
)
</insert>
<insertid="com.fashionfree.stat.accesslog.MemberAccessLog.insert"
parameterClass="com.fashionfree.stat.accesslog.model.MemberAccessLog>
insertintoMemberAccessLog
(
accessLogId,memberId,clientIP,
httpMethod,actionId,requestURL,
accessTimestamp,extend1,extend2,
extend3
)
values
(
#accessLogId#,#memberId#,
#clientIP#,#httpMethod#,
#actionId#,#requestURL#,
#accessTimestamp#,#extend1#,
#extend2#,#extend3#
)
</insert>

3.输入参数为一个java.util.HashMap

<selectid="com.fashionfree.stat.accesslog.selectActionIdAndActionNumber"
parameterClass="hashMap"
resultMap="getActionIdAndActionNumber">
select
actionId,count(*)ascount
from
MemberAccessLog
where
memberId=#memberId#
andaccessTimestamp&gt;#start#
andaccessTimestamp&lt;=#end#
groupbyactionId
</select>
<selectid="com.fashionfree.stat.accesslog.selectActionIdAndActionNumber"
parameterClass="hashMap"
resultMap="getActionIdAndActionNumber">
select
actionId,count(*)ascount
from
MemberAccessLog
where
memberId=#memberId#
andaccessTimestamp&gt;#start#
andaccessTimestamp&lt;=#end#
groupbyactionId
</select>

4.输入参数中含有数组

<insertid="updateStatusBatch"parameterClass="hashMap">
update
Question
set
status=#status#
<dynamicprepend="wherequestionIdin">
<isNotNullproperty="actionIds">
<iterateproperty="actionIds"open="("close=")"conjunction=",">
#actionIds[]#
</iterate>
</isNotNull>
</dynamic>
</insert>
<insertid="updateStatusBatch"parameterClass="hashMap">
update
Question
set
status=#status#
<dynamicprepend="wherequestionIdin">
<isNotNullproperty="actionIds">
<iterateproperty="actionIds"open="("close=")"conjunction=",">
#actionIds[]#
</iterate>
</isNotNull>
</dynamic>
</insert>

说明：actionIds为传入的数组的名字；使用dynamic标签避免数组为空时导致sql语句语法出错；使用isNotNull标签避免数组为null时ibatis解析出错

5.传递参数只含有一个数组

<selectid="com.fashionfree.stat.accesslog.model.StatMemberAction.selectActionIdsOfModule"
resultClass="hashMap">
select
moduleId,actionId
from
StatMemberAction
<dynamicprepend="wheremoduleIdin">
<iterateopen="("close=")"conjunction=",">
#[]#
</iterate>
</dynamic>
orderby
moduleId
</select>
<selectid="com.fashionfree.stat.accesslog.model.StatMemberAction.selectActionIdsOfModule"
resultClass="hashMap">
select
moduleId,actionId
from
StatMemberAction
<dynamicprepend="wheremoduleIdin">
<iterateopen="("close=")"conjunction=",">
#[]#
</iterate>
</dynamic>
orderby
moduleId
</select>

说明：注意select的标签中没有parameterClass一项

另：这里也可以把数组放进一个hashMap中，但增加额外开销，不建议使用

6.让ibatis把参数直接解析成字符串

<selectid="com.fashionfree.stat.accesslog.selectSumDistinctCountOfAccessMemberNum"
parameterClass="hashMap"resultClass="int">
select
count(distinctmemberId)
from
MemberAccessLog
where
accessTimestamp&gt;=#start#
andaccessTimestamp&lt;#end#
andactionIdin$actionIdString$
</select>
<selectid="com.fashionfree.stat.accesslog.selectSumDistinctCountOfAccessMemberNum"
parameterClass="hashMap"resultClass="int">
select
count(distinctmemberId)
from
MemberAccessLog
where
accessTimestamp&gt;=#start#
andaccessTimestamp&lt;#end#
andactionIdin$actionIdString$
</select>

说明：使用这种方法存在sql注入的风险，不推荐使用

7.分页查询(pagedQuery)

<selectid="com.fashionfree.stat.accesslog.selectMemberAccessLogBy"
parameterClass="hashMap"resultMap="MemberAccessLogMap">
<includerefid="selectAllSql"/>
<includerefid="whereSql"/>
<includerefid="pageSql"/>
</select>
<selectid="com.fashionfree.stat.accesslog.selectMemberAccessLogBy.Count"
parameterClass="hashMap"resultClass="int">
<includerefid="countSql"/>
<includerefid="whereSql"/>
</select>
<sqlid="selectAllSql">
select
accessLogId,memberId,clientIP,
httpMethod,actionId,requestURL,
accessTimestamp,extend1,extend2,
extend3
from
MemberAccessLog
</sql>
<sqlid="whereSql">
accessTimestamp&lt;=#accessTimestamp#
</sql>
<sqlid="countSql">
select
count(*)
from
MemberAccessLog
</sql>
<sqlid="pageSql">
<dynamic>
<isNotNullproperty="startIndex">
<isNotNullproperty="pageSize">
limit#startIndex#,#pageSize#
</isNotNull>
</isNotNull>
</dynamic>
</sql>
<selectid="com.fashionfree.stat.accesslog.selectMemberAccessLogBy"
parameterClass="hashMap"resultMap="MemberAccessLogMap">
<includerefid="selectAllSql"/>
<includerefid="whereSql"/>
<includerefid="pageSql"/>
</select>
<selectid="com.fashionfree.stat.accesslog.selectMemberAccessLogBy.Count"
parameterClass="hashMap"resultClass="int">
<includerefid="countSql"/>
<includerefid="whereSql"/>
</select>
<sqlid="selectAllSql">
select
accessLogId,memberId,clientIP,
httpMethod,actionId,requestURL,
accessTimestamp,extend1,extend2,
extend3
from
MemberAccessLog
</sql>
<sqlid="whereSql">
accessTimestamp&lt;=#accessTimestamp#
</sql>
<sqlid="countSql">
select
count(*)
from
MemberAccessLog
</sql>
<sqlid="pageSql">
<dynamic>
<isNotNullproperty="startIndex">
<isNotNullproperty="pageSize">
limit#startIndex#,#pageSize#
</isNotNull>
</isNotNull>
</dynamic>
</sql>

说明：本例中，代码应为：

HashMaphashMap=newHashMap();
hashMap.put(“accessTimestamp”,someValue);
pagedQuery(“com.fashionfree.stat.accesslog.selectMemberAccessLogBy”,hashMap);

pagedQuery方法首先去查找名为com.fashionfree.stat.accesslog.selectMemberAccessLogBy.Count的mappedstatement来进行sql查询，从而得到com.fashionfree.stat.accesslog.selectMemberAccessLogBy查询的记录个数，再进行所需的pagedsql查询(com.fashionfree.stat.accesslog.selectMemberAccessLogBy)，具体过程参见utils类中的相关代码

8.sql语句中含有大于号>、小于号<1.将大于号、小于号写为：><如：

<deleteid="com.fashionfree.stat.accesslog.deleteMemberAccessLogsBefore"parameterClass="long">
deletefrom
MemberAccessLog
where
accessTimestamp&lt;=#value#
</delete>
Xml代码
<deleteid="com.fashionfree.stat.accesslog.deleteMemberAccessLogsBefore"parameterClass="long">
deletefrom
MemberAccessLog
where
accessTimestamp&lt;=#value#
</delete>

将特殊字符放在xml的CDATA区内：

<deleteid="com.fashionfree.stat.accesslog.deleteMemberAccessLogsBefore"parameterClass="long">
<![CDATA[
deletefrom
MemberAccessLog
where
accessTimestamp<=#value#
]]>
</delete>
<deleteid="com.fashionfree.stat.accesslog.deleteMemberAccessLogsBefore"parameterClass="long">
<![CDATA[
deletefrom
MemberAccessLog
where
accessTimestamp<=#value#
]]>
</delete>

推荐使用第一种方式，写为<和>(XML不对CDATA里的内容进行解析，因此如果CDATA中含有dynamic标签，将不起作用)

9.include和sql标签将常用的sql语句整理在一起，便于共用：

<sqlid="selectBasicSql">
select
samplingTimestamp,onlineNum,year,
month,week,day,hour
from
OnlineMemberNum
</sql>
<sqlid="whereSqlBefore">
wheresamplingTimestamp&lt;=#samplingTimestamp#
</sql>
<selectid="com.fashionfree.accesslog.selectOnlineMemberNumsBeforeSamplingTimestamp"parameterClass="hashmap"resultClass="OnlineMemberNum">
<includerefid="selectBasicSql"/>
<includerefid="whereSqlBefore"/>
</select>
<sqlid="selectBasicSql">
select
samplingTimestamp,onlineNum,year,
month,week,day,hour
from
OnlineMemberNum
</sql>
<sqlid="whereSqlBefore">
wheresamplingTimestamp&lt;=#samplingTimestamp#
</sql>
<selectid="com.fashionfree.accesslog.selectOnlineMemberNumsBeforeSamplingTimestamp"parameterClass="hashmap"resultClass="OnlineMemberNum">
<includerefid="selectBasicSql"/>
<includerefid="whereSqlBefore"/>
</select>

注意：sql标签只能用于被引用，不能当作mappedstatement。如上例中有名为selectBasicSql的sql元素，试图使用其作为sql语句执行是错误的:

sqlMapClient.queryForList(“selectBasicSql”);×

10.随机选取记录

<sqlid=”randomSql”>
ORDERBYrand()LIMIT#number#
</sql>

从数据库中随机选取number条记录（只适用于MySQL）

11.将SQLGROUPBY分组中的字段拼接

<sqlid=”selectGroupBy>
SELECT
a.answererCategoryId,a.answererId,a.answererName,
a.questionCategoryId,a.score,a.answeredNum,
a.correctNum,a.answerSeconds,a.createdTimestamp,
a.lastQuestionApprovedTimestamp,a.lastModified,GROUP_CONCAT(q.categoryName)ascategoryName
FROM
AnswererCategorya,QuestionCategoryq
WHEREa.questionCategoryId=q.questionCategoryId
GROUPBYa.answererId
ORDERBYa.answererCategoryId
</sql>
<sqlid=”selectGroupBy>
SELECT
a.answererCategoryId,a.answererId,a.answererName,
a.questionCategoryId,a.score,a.answeredNum,
a.correctNum,a.answerSeconds,a.createdTimestamp,
a.lastQuestionApprovedTimestamp,a.lastModified,GROUP_CONCAT(q.categoryName)ascategoryName
FROM
AnswererCategorya,QuestionCategoryq
WHEREa.questionCategoryId=q.questionCategoryId
GROUPBYa.answererId
ORDERBYa.answererCategoryId
</sql>

注：SQL中使用了MySQL的GROUP_CONCAT函数

12.按照IN里面的顺序进行排序

①MySQL:

<sqlid=”groupByInArea”>
select
moduleId,moduleName,
status,lastModifierId,lastModifiedName,
lastModified
from
StatModule
where
moduleIdin(3,5,1)
orderby
instr(',3,5,1,',','+ltrim(moduleId)+',')
</sql>
<sqlid=”groupByInArea”>
select
moduleId,moduleName,
status,lastModifierId,lastModifiedName,
lastModified
from
StatModule
where
moduleIdin(3,5,1)
orderby
instr(',3,5,1,',','+ltrim(moduleId)+',')
</sql>

②SQLSERVER:

<sqlid=”groupByInArea”>
select
moduleId,moduleName,
status,lastModifierId,lastModifiedName,
lastModified
from
StatModule
where
moduleIdin(3,5,1)
orderby
charindex(','+ltrim(moduleId)+',',',3,5,1,')
</sql>
<sqlid=”groupByInArea”>
select
moduleId,moduleName,
status,lastModifierId,lastModifiedName,
lastModified
from
StatModule
where
moduleIdin(3,5,1)
orderby
charindex(','+ltrim(moduleId)+',',',3,5,1,')
</sql>

说明：查询结果将按照moduleId在in列表中的顺序(3,5,1)来返回

MySQL:instr(str,substr)

SQLSERVER:charindex(substr,str)返回字符串str中子字符串的第一个出现位置ltrim(str)返回字符串str,其引导(左面的)空格字符被删除

13.resultMapresultMap负责将SQL查询结果集的列值映射成JavaBean的属性值

<resultMapclass="java.util.HashMap"id="getActionIdAndActionNumber">
<resultcolumn="actionId"property="actionId"jdbcType="BIGINT"javaType="long"/>
<resultcolumn="count"property="count"jdbcType="INT"javaType="int"/>
</resultMap>
Xml代码
<resultMapclass="java.util.HashMap"id="getActionIdAndActionNumber">
<resultcolumn="actionId"property="actionId"jdbcType="BIGINT"javaType="long"/>
<resultcolumn="count"property="count"jdbcType="INT"javaType="int"/>
</resultMap>

使用resultMap称为显式结果映射，与之对应的是resultClass(内联结果映射)，使用resultClass的最大好处便是简单、方便，不需显示指定结果，由iBATIS根据反射来确定自行决定。而resultMap则可以通过指定jdbcType和javaType，提供更严格的配置认证。

14.typeAlias

<typeAliasalias="MemberOnlineDuration"type="com.fashionfree.stat.accesslog.model.MemberOnlineDuration"/>
<typeAlias>

允许你定义别名，避免重复输入过长的名字

15.remap

<selectid="testForRemap"parameterClass="hashMap"resultClass="hashMap"remapResults="true">
select
userId
<isEqualproperty="tag"compareValue="1">
,userName
</isEqual>
<isEqualproperty="tag"compareValue="2">
,userPassword
</isEqual>
from
UserInfo
</select>
<selectid="testForRemap"parameterClass="hashMap"resultClass="hashMap"remapResults="true">
select
userId
<isEqualproperty="tag"compareValue="1">
,userName
</isEqual>
<isEqualproperty="tag"compareValue="2">
,userPassword
</isEqual>
from
UserInfo
</select>

此例中，根据参数tag值的不同，会获得不同的结果集，如果没有remapResults="true"属性，iBatis会将第一次查询时的结果集缓存，下次再执行时（必须还是该进程中）不会再执行结果集映射，而是会使用缓存的结果集。

因此，如果上面的例子中remapResult为默认的false属性，而有一段程序这样书写：

HashMap<String,Integer>hashMap=newHashMap<String,Integer>();
hashMap.put("tag",1);
sqlClient.queryForList("testForRemap",hashMap);
hashMap.put("tag",2);
sqlClient.queryForList("testForRemap",hashMap);

Java代码

HashMap<String,Integer>hashMap=newHashMap<String,Integer>();
hashMap.put("tag",1);
sqlClient.queryForList("testForRemap",hashMap);
hashMap.put("tag",2);
sqlClient.queryForList("testForRemap",hashMap);

则程序会在执行最后一句的query查询时报错，原因就是iBATIS使用了第一次查询时的结果集，而前后两次的结果集是不同的:(userId,userName)和(userId,userPassword)，所以导致出错。如果使用了remapResults="true"这一属性，iBATIS会在每次执行查询时都执行结果集映射，从而避免错误的发生（此时会有较大的开销）。

16.dynamic标签的prependdynamic标签的prepend属性作为前缀添加到结果内容前面，当标签的结果内容为空时，prepend属性将不起作用。

当dynamic标签中存在prepend属性时，将会把其嵌套子标签的第一个prepend属性忽略。例如：

<sqlid="whereSql">
<dynamicprepend="where">
<isNotNullproperty="userId"prepend="BOGUS">
userId=#userId#
</isNotNull>
<isNotEmptyproperty="userName"prepend="and">
userName=#userName#
</isNotEmpty>
</dynamic>
</sql>
<sqlid="whereSql">
<dynamicprepend="where">
<isNotNullproperty="userId"prepend="BOGUS">
userId=#userId#
</isNotNull>
<isNotEmptyproperty="userName"prepend="and">
userName=#userName#
</isNotEmpty>
</dynamic>
</sql>

此例中，dynamic标签中含有两个子标签<isNotNull>和<isNotEmpty>。根据前面叙述的原则，如果<isNotNull>标签中没有prepend="BOGUS"这一假的属性来让dynamic去掉的话，<isNotEmpty>标签中的and就会被忽略，会造成sql语法错误。

注意：当dynamic标签没有prepend属性时，不会自动忽略其子标签的第一个prepend属性。

以上所述是小编给大家介绍的iBatis习惯用的16条SQL语句，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对毛票票网站的支持！

iBatis习惯用的16条SQL语句

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