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ibatis的动态sql
2022-07-05 11:21:00 【全栈程序员站长】
1.介绍
1 <select id="getUsers"
2
3 parameterClass="user"
4
5 resultMap="get-user-result">
6
7 select
8
9 id,
10
11 name,
12
13 sex
14
15 from t_user
16
17 <dynamic prepend="WHERE">
18
19 <isNotEmpty prepend="AND" property="name">
20
21 name like #name#
22
23 </isNotEmpty>
24
25 <isNotEmpty prepend="AND" property="address">
26
27 address like #address#
28
29 </isNotEmpty>
30
31 </dynamic>
32
33 </select>
通过dynamic 节点,可以定义了一个动态的WHERE 子句。此WHERE 子句中将可能包含两个针对name 和address 字段的判断条件。而这两个字段是否加入检索取决于用户所提供的查询条件。
这个节点对应的语义是,如果参数类的”name”属性非空(isNotEmpty,即非空字符串””),则在生成的SQL Where字句中包括判定条件(name like #name#),其中#name#将以参数类的name属性值填充。
name属性对应的isNotEmpty节点,由于ibatis会自动判定是否需要追加prepend前缀,这里(name like #name#)是WHERE 子句中的第一个条件子句,无需AND 前缀,所以自动省略。
判定节点并非仅限于isNotEmpty,ibatis中提供了丰富的判定定义功能。可以分两类:
一、 一元判定
一元判定是针对属性值本身的判定,如属性是否为NULL,是否为空值等。
上面示例中isNotEmpty就是典型的一元判定。
一元判定节点有:
<isPropertyAvailable> 参数类中是否提供了此属性
<isNotPropertyAvailable> 与<isPropertyAvailable>相反
<isNull> 属性值是否为NULL
<isNotNull> 与<isNull>相反
<isEmpty> 如果属性为Collection或者String,其size是否<1,
如果非以上两种类型,则通过
String.valueOf(属性值)
获得其String类型的值后,判断其size是否<1
<isNotEmpty> 与<isEmpty>相反。
二、二元判定
二元判定有两个判定参数,一是属性名,而是判定值,如
<isGreaterThan prepend=”AND” property=”age”
compareValue=”18″>
(age=#age#)
</isGreaterThan>
其中,property=”age”指定了属性名”age”,compareValue=”18”指明
了判定值为”18”。
上面判定节点isGreaterThan 对应的语义是:如果age 属性大于
18(compareValue),则在SQL中加入(age=#age#)条件。
二元判定节点有:
节点名 属性值与compareValues的关系
<isEqual> 相等。
<isNotEqual> 不等。
<isGreaterThan> 大于
<isGreaterEqual> 大于等于
<isLessThan> 小于
<isLessEqual> 小于等于
2.列子
对于一些特殊符号,如大于号>、小于号< 等需要写在<![CDATA[]]中方可有效,否则失效。 1、动态SQL片段
通过SQL片段达到代码复用
1 <!-- 动态条件分页查询 -->
2 <sql id="sql_count">
3 select count(*)
4 </sql>
5 <sql id="sql_select">
6 select *
7 </sql>
8 <sql id="sql_where">
9 from icp
10 <dynamic prepend="where">
11 <isNotEmpty prepend="and" property="name">
12 name like '%$name$%'
13 </isNotEmpty>
14 <isNotEmpty prepend="and" property="path">
15 path like '%path$%'
16 </isNotEmpty>
17 <isNotEmpty prepend="and" property="area_id">
18 area_id = #area_id#
19 </isNotEmpty>
20 <isNotEmpty prepend="and" property="hided">
21 hided = #hided#
22 </isNotEmpty>
23 </dynamic>
24 <dynamic prepend="">
25 <isNotNull property="_start">
26 <isNotNull property="_size">
27 limit #_start#, #_size#
28 </isNotNull>
29 </isNotNull>
30 </dynamic>
31 </sql>
32 <select id="findByParamsForCount" parameterClass="map" resultClass="int">
33 <include refid="sql_count"/>
34 <include refid="sql_where"/>
35 </select>
36 <select id="findByParams" parameterClass="map" resultMap="icp.result_base">
37 <include refid="sql_select"/>
38 <include refid="sql_where"/>
39
40 </select>
2、数字范围查询
所传参数名称是捏造所得,非数据库字段,比如_img_size_ge、_img_size_lt字段
1 <isNotEmpty prepend="and" property="_img_size_ge">
2 <![CDATA[
3 img_size >= #_img_size_ge#
4 ]]>
5 </isNotEmpty>
6 <isNotEmpty prepend="and" property="_img_size_lt">
7 <![CDATA[
8 img_size < #_img_size_lt#
9 ]]>
10 </isNotEmpty>
11
12
多次使用一个参数也是允许的
1 <isNotEmpty prepend="and" property="_now">
2 <![CDATA[
3 execplantime >= #_now#
4 ]]>
5 </isNotEmpty>
6 <isNotEmpty prepend="and" property="_now">
7 <![CDATA[
8 closeplantime <= #_now#
9 ]]>
10 </isNotEmpty>
3、时间范围查询
1 <isNotEmpty prepend="" property="_starttime">
2 <isNotEmpty prepend="and" property="_endtime">
3 <![CDATA[
4 createtime >= #_starttime#
5 and createtime < #_endtime#
6 ]]>
7 </isNotEmpty>
8 </isNotEmpty>
4、in查询
1 <isNotEmpty prepend="and" property="_in_state">
2 state in ('$_in_state$')
3 </isNotEmpty>
5、like查询
1 <isNotEmpty prepend="and" property="chnameone">
2 (chnameone like '%$chnameone$%' or spellinitial like '%$chnameone$%')
3 </isNotEmpty>
4 <isNotEmpty prepend="and" property="chnametwo">
5 chnametwo like '%$chnametwo$%'
6 </isNotEmpty>
6、or条件
1 <isEqual prepend="and" property="_exeable" compareValue="N">
2 <![CDATA[
3 (t.finished='11' or t.failure=3)
4 ]]>
5 </isEqual>
6
7 <isEqual prepend="and" property="_exeable" compareValue="Y">
8 <![CDATA[
9 t.finished in ('10','19') and t.failure<3
10 ]]>
11 </isEqual>
7、where子查询
1 <isNotEmpty prepend="" property="exprogramcode">
2 <isNotEmpty prepend="" property="isRational">
3 <isEqual prepend="and" property="isRational" compareValue="N">
4 code not in
5 (select t.contentcode
6 from cms_ccm_programcontent t
7 where t.contenttype='MZNRLX_MA'
8 and t.programcode = #exprogramcode#)
9 </isEqual>
10 </isNotEmpty>
11 </isNotEmpty>
12
13 <select id="findByProgramcode" parameterClass="string" resultMap="cms_ccm_material.result">
14 select *
15 from cms_ccm_material
16 where code in
17 (select t.contentcode
18 from cms_ccm_programcontent t
19 where t.contenttype = 'MZNRLX_MA'
20 and programcode = #value#)
21 order by updatetime desc
22 </select>
9、函数的使用
1 <!-- 添加 -->
2 <insert id="insert" parameterClass="RuleMaster">
3 insert into rulemaster(
4 name,
5 createtime,
6 updatetime,
7 remark
8 ) values (
9 #name#,
10 now(),
11 now(),
12 #remark#
13 )
14 <selectKey keyProperty="id" resultClass="long">
15 select LAST_INSERT_ID()
16 </selectKey>
17 </insert>
18 <!-- 更新 -->
19 <update id="update" parameterClass="RuleMaster">
20 update rulemaster set
21 name = #name#,
22 updatetime = now(),
23 remark = #remark#
24 where id = #id#
25 </update>
10、map结果集
1 <!-- 动态条件分页查询 -->
2 <sql id="sql_count">
3 select count(a.*)
4 </sql>
5 <sql id="sql_select">
6 select a.id vid,
7 a.img imgurl,
8 a.img_s imgfile,
9 b.vfilename vfilename,
10 b.name name,
11 c.id sid,
12 c.url url,
13 c.filename filename,
14 c.status status
15 </sql>
16 <sql id="sql_where">
17 From secfiles c, juji b, videoinfo a
18 where
19 a.id = b. videoid
20 and b.id = c.segmentid
21 and c.status = 0
22 order by a.id asc,b.id asc,c.sortnum asc
23 <dynamic prepend="">
24 <isNotNull property="_start">
25 <isNotNull property="_size">
26 limit #_start#, #_size#
27 </isNotNull>
28 </isNotNull>
29 </dynamic>
30 </sql>
31 <!-- 返回没有下载的记录总数 -->
32 <select id="getUndownFilesForCount" parameterClass="map" resultClass="int">
33 <include refid="sql_count"/>
34 <include refid="sql_where"/>
35 </select>
36 <!-- 返回没有下载的记录 -->
37 <select id="getUndownFiles" parameterClass="map" resultClass="java.util.HashMap">
38 <include refid="sql_select"/>
39 <include refid="sql_where"/>
40 </select>
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