转：ibatis常用16条SQL语句

1.输入参数为单个值

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

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

2.输入参数为一个对象

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

 <insert id="com.fashionfree.stat.accesslog.MemberAccessLog.insert"
 parameterClass="com.fashionfree.stat.accesslog.model.MemberAccessLog>
 insert into MemberAccessLog
 (
 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

<select id="com.fashionfree.stat.accesslog.selectActionIdAndActionNumber"
 parameterClass="hashMap"
 resultMap="getActionIdAndActionNumber">
 select
 actionId, count(*) as count
 from
 MemberAccessLog
 where
 memberId = #memberId#
 and accessTimestamp &gt; #start#
 and accessTimestamp &lt;= #end#
 group by actionId
 </select>

<select id="com.fashionfree.stat.accesslog.selectActionIdAndActionNumber"
 parameterClass="hashMap"
 resultMap="getActionIdAndActionNumber">
 select
 actionId, count(*) as count
 from
 MemberAccessLog
 where
 memberId = #memberId#
 and accessTimestamp &gt; #start#
 and accessTimestamp &lt;= #end#
 group by actionId
 </select>

4.输入参数中含有数组

<insert id="updateStatusBatch" parameterClass="hashMap">
 update
 Question
 set
 status = #status#
 <dynamic prepend="where questionId in">
 <isNotNull property="actionIds">
 <iterate property="actionIds" open="(" close=")" conjunction=",">
 #actionIds[]#
 </iterate>
 </isNotNull>
 </dynamic>
 </insert>   

 <insert id="updateStatusBatch" parameterClass="hashMap">
 update
 Question
 set
 status = #status#
 <dynamic prepend="where questionId in">
 <isNotNull property="actionIds">
 <iterate property="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

<select id="com.fashionfree.stat.accesslog.model.StatMemberAction.selectActionIdsOfModule"
 resultClass="hashMap">
 select
 moduleId, actionId
 from
 StatMemberAction
 <dynamic prepend="where moduleId in">
 <iterate open="(" close=")" conjunction=",">
 #[]#
 </iterate>
 </dynamic>
 order by
 moduleId
 </select>

 <select id="com.fashionfree.stat.accesslog.model.StatMemberAction.selectActionIdsOfModule"
 resultClass="hashMap">
 select
 moduleId, actionId
 from
 StatMemberAction
 <dynamic prepend="where moduleId in">
 <iterate open="(" close=")" conjunction=",">
 #[]#
 </iterate>
 </dynamic>
 order by
 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

<select id="com.fashionfree.stat.accesslog.selectSumDistinctCountOfAccessMemberNum"
 parameterClass="hashMap" resultClass="int">
 select
 count(distinct memberId)
 from
 MemberAccessLog
 where
 accessTimestamp &gt;= #start#
 and accessTimestamp &lt; #end#
 and actionId in $actionIdString$
 </select>  

 <select id="com.fashionfree.stat.accesslog.selectSumDistinctCountOfAccessMemberNum"
 parameterClass="hashMap" resultClass="int">
 select
 count(distinct memberId)
 from
 MemberAccessLog
 where
 accessTimestamp &gt;= #start#
 and accessTimestamp &lt; #end#
 and actionId in $actionIdString$
 </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)

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

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

说明：本例中，代码应为：

    HashMap hashMap = new HashMap();
    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mapped statement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paged sql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： &gt; &lt; 如：

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

    将特殊字符放在xml的CDATA区内：

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

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

推荐使用第一种方式，写为&lt; 和 &gt; (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：

<sql id="selectBasicSql">
 select
 samplingTimestamp,onlineNum,year,
 month,week,day,hour
 from
 OnlineMemberNum
 </sql>
 <sql id="whereSqlBefore">
 where samplingTimestamp &lt;= #samplingTimestamp#
 </sql>
 <select id="com.fashionfree.accesslog.selectOnlineMemberNumsBeforeSamplingTimestamp" parameterClass="hashmap" resultClass="OnlineMemberNum">
 <include refid="selectBasicSql" />
 <include refid="whereSqlBefore" />
 </select>   

 <sql id="selectBasicSql">
 select
 samplingTimestamp,onlineNum,year,
 month,week,day,hour
 from
 OnlineMemberNum
 </sql>
 <sql id="whereSqlBefore">
 where samplingTimestamp &lt;= #samplingTimestamp#
 </sql>
 <select id="com.fashionfree.accesslog.selectOnlineMemberNumsBeforeSamplingTimestamp" parameterClass="hashmap" resultClass="OnlineMemberNum">
 <include refid="selectBasicSql" />
 <include refid="whereSqlBefore" />
 </select>   

注意：sql标签只能用于被引用，不能当作mapped statement。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

<sql id=”randomSql”>
 ORDER BY rand() LIMIT #number#
 </sql>

从数据库中随机选取number条记录（只适用于MySQL）

11.将SQL GROUP BY分组中的字段拼接

<sql id=”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) as categoryName
 FROM
 AnswererCategory a, QuestionCategory q
 WHERE a.questionCategoryId = q.questionCategoryId
 GROUP BY a.answererId
 ORDER BY a.answererCategoryId
 </sql>

 <sql id=”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) as categoryName
 FROM
 AnswererCategory a, QuestionCategory q
 WHERE a.questionCategoryId = q.questionCategoryId
 GROUP BY a.answererId
 ORDER BY a.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:

 <sql id=”groupByInArea”>
 select
 moduleId, moduleName,
 status, lastModifierId, lastModifiedName,
 lastModified
 from
 StatModule
 where
 moduleId in (3, 5, 1)
 order by
 instr(',3,5,1,' , ','+ltrim(moduleId)+',')
 </sql>   

 <sql id=”groupByInArea”>
 select
 moduleId, moduleName,
 status, lastModifierId, lastModifiedName,
 lastModified
 from
 StatModule
 where
 moduleId in (3, 5, 1)
 order by
 instr(',3,5,1,' , ','+ltrim(moduleId)+',')
 </sql>   

②SQLSERVER:

 <sql id=”groupByInArea”>
 select
 moduleId, moduleName,
 status, lastModifierId, lastModifiedName,
 lastModified
 from
 StatModule
 where
 moduleId in (3, 5, 1)
 order by
 charindex(','+ltrim(moduleId)+',' , ',3,5,1,')
 </sql>  

 <sql id=”groupByInArea”>
 select
 moduleId, moduleName,
 status, lastModifierId, lastModifiedName,
 lastModified
 from
 StatModule
 where
 moduleId in (3, 5, 1)
 order by
 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.resultMap resultMap负责将SQL查询结果集的列值映射成Java Bean的属性值

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

<typeAlias alias="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

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

 <select id="testForRemap" parameterClass="hashMap" resultClass="hashMap" remapResults="true">
 select
 userId
 <isEqual property="tag" compareValue="1">
 , userName
 </isEqual>
 <isEqual property="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 = new HashMap<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 = new HashMap<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prepend dynamic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：

 <sql id="whereSql">
 <dynamic prepend="where ">
 <isNotNull property="userId" prepend="BOGUS">
 userId = #userId#
 </isNotNull>
 <isNotEmpty property="userName" prepend="and ">
 userName = #userName#
 </isNotEmpty>
 </dynamic>
 </sql>  

 <sql id="whereSql">
 <dynamic prepend="where ">
 <isNotNull property="userId" prepend="BOGUS">
 userId = #userId#
 </isNotNull>
 <isNotEmpty property="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。