java - 在 MyBatis 中列出 'IN' 子句

Question

<分区>

Answer 1

当与列表一起使用时，item 属性指定的值应该在 foreach 标签内使用。使用如下:

    <foreach item="sId" collection="stripperIds" separator="," open="(" close=")">
        #{sId}
    </foreach>

当使用列表时，索引属性不是强制性的。请参阅 MyBatis 文档部分以获取更多信息，或查看 DTD - http://mybatis.org/dtd/mybatis-3-mapper.dtd有关参数的更多信息:

    <!ELEMENT foreach (#PCDATA | include | trim | where | set | foreach | choose | if | bind)*>
    <!ATTLIST foreach
    collection CDATA #REQUIRED
    item CDATA #IMPLIED
    index CDATA #IMPLIED
    open CDATA #IMPLIED
    close CDATA #IMPLIED
    separator CDATA #IMPLIED
    >

此外，对象列表可以在 foreach 中访问，如下所示。您通常会将其用于 INSERT/UPDATE 语句:

示例 bean:

public class StripperBean {

    public StripperBean(int stripperID, String stripperName, String realName) {
        this.stripperID = stripperID;
        this.stripperName = stripperName;
        this.realName = realName;
    }

    private int stripperID; 
    private String stripperName;
    private String realName;        

    public int getStripperID() {
        return stripperID;
    }
    public void setStripperID(int stripperID) {
        this.stripperID = stripperID;
    }
    public String getStripperName() {
        return stripperName;
    }
    public void setStripperName(String stripperName) {
        this.stripperName = stripperName;
    }
    public String getRealName() {
        return realName;
    }
    public void setRealName(String realName) {
        this.realName = realName;
    }       
}

在您的实现中:

    Map<String, Object> input = new HashMap<>();
    input.put("club", club);
    List<StripperBean> strippers = new ArrayList<>();
    strippers.add(new StripperBean(1,"Ashley", "Jean Grey"));
    strippers.add(new StripperBean(2,"Candice","Diana Prince"));
    strippers.add(new StripperBean(3,"Cristal","Lara Croft"));        
    input.put("strippers", strippers);
    return stripClubMapper.saveStripperDetails(input);

在映射器 xml 中:

    <insert id="saveStripperDetails">
        INSERT INTO EXOTIC_DANCERS (STRIPPER_ID, STAGE_NAME, REAL_NAME)
        VALUES
        <foreach item="stripper" collection="input" separator=",">
            (#{stripper.stripperID},
            #{stripper.stripperName},
            #{stripper.realName})
        </foreach>
    </select>

顺便问个好问题 :)