iBatis中的动态查询

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如果想深入学习，可以参考 Manning.                  iBATIS.in.Action.Jan.2007
下面给出几个例子和dtd定义：
<                  selectid="selectDispatchedKey" parameterClass="KeyAndKeyFlowInfo" resultMap="KeyAndKeyFlowResult">
   select distinct
    KEY_ID,
    USER_ID,
    INITIATOR,
    INIT_DATE,
    INITIATOR_EMAIL,
    SGS_KEY.BRANCH_NAME,
    APPROVER,
    APPROVER_EMAIL,
    APPROVE_DATE
   from
    SGS_KEY,
    SGS_KEY_FLOW
   where SGS_KEY.APPLY_FLOW_ID=SGS_KEY_FLOW.KEY_FLOW_ID
   <                  dynamicprepend="and"                  open="(" close=")">
    <                  isNotNullproperty="ki.userId" prepend="and" removeFirstPrepend="false">
     USER_ID = #ki.userId#
    </                  isNotNull>
    <                  isNotNullproperty="kfi.initiator"                 prepend="and">
     INITIATOR = #kfi.initiator#
    </                  isNotNull>
    <                  isNotNullproperty="kfi.initDate"                 prepend="and">
     INIT_DATE = #kfi.initDate#
    </                  isNotNull>
   </                  dynamic>
< /select>

<                  updateid="updateKeyFlow" parameterClass="KeyFlowInfo">
   update SGS_KEY_FLOW set
   <                  dynamic>
     KEY_FLOW_ID =#keyFlowId#
    <isNotNull property="branchName" prepend=",">
     BRANCH_NAME = #branchName#
    </isNotNull>
    <isNotEqual property="operation" prepend="," compareProperty="operation" compareValue="0">
     OPERATION = #operation#
    </isNotEqual>
    <isNotNull property="initiator" prepend=",">
     INITIATOR = #initiator#
    </isNotNull>
    <isNotNull property="initiatorEmail" prepend=",">
     INITIATOR_EMAIL = #initiatorEmail#
    </isNotNull>
    <isNotNull property="initDate" prepend=",">
     INIT_DATE = #initDate#
    </isNotNull>
    <isNotNull property="approver" prepend=",">
     APPROVER = #approver#
    </isNotNull>
    <isNotNull property="approverEmail" prepend=",">
     APPROVER_EMAIL = #approverEmail#
    </isNotNull>
    <isNotNull property="approveDate" prepend=",">
     APPROVE_DATE = #approveDate#
    </isNotNull>
    <isNotEqual property="keyNum" prepend="," compareProperty="keyNum" compareValue="0">
     KEY_NUM = #keyNum#
    </isNotEqual>
    <isNotNull property="applyReason" prepend=",">
     APPLY_REASON = #applyReason#
    </isNotNull>
    <isNotNull property="rejectReason" prepend=",">
     REJECT_REASON = #rejectReason#
    </isNotNull>
   </                  dynamic>
   where
    KEY_FLOW_ID =#keyFlowId#
< /update>


属性关键字
                             含义

<isEqual>
如果参数相等于值                             则查询条件有效。

<isNotEqual>
如果参数不等于值则查询条件有效。

<isGreaterThan>
如果参数大于值则查询条件有效。

<isGreaterEqual>
如果参数等于值则查询条件有效。

<isLessEqual>
如果参数小于值则查询条件有效。如下所示：
<isLessEqual prepend = ”AND” property = ”age” compareValue = ”18” >
ADOLESCENT = ‘TRUE’
</isLessEqual>

                            < isPropertyAvailable>
如果参数有使用则查询条件有效。

<isNotPropertyAvailable>
如果参数没有使用则查询条件有效。

<isNull>
如果参数为NULL则查询条件有效。

<isNotNull>
如果参数不为NULL则查询条件有效。

<isEmpty>
如果参数为空则查询条件有效。

<isNotEmpty>
如果参数不为空则查询条件有效                             。参数的数据类型为                            Collection                            、                            String                            时参数不为                            NULL                            或“”。如下所示：
<isNotEmpty prepend=”AND” property=”firstName” >
FIRST_NAME=#firstName#
                            < /isNotEmpty>

                                                          < isParameterPresent>
如果参数类不为NULL                            则查询条件有效。

<isNotParameterPresent>
                             Checks to see if the parameter object is not present (null). Example Usage:
                            < isNotParameterPresent prepend=”AND”>
EMPLOYEE_TYPE = ‘DEFAULT’
</isNotParameterPresent>