leaflet hello world

$和#的区别

A #{} 解析为一个预编译语句（prepared statement）的参数标记符，是根据传入类型来动态替换

• #{} 能很好的防止sql注入，因为是动态参数转换

B ${} 仅仅为一个纯碎的 string 替换，在动态 SQL 解析阶段将会进行变量替换，是直接替换

• 由于 ${} 为字符串直接替换，所以会有sql注入的风险
• ${} 适用场景 order by 或 limit 拼接

mybaits常见问题

todo

mybatis 向上递归查询 向下递归查询

bean

public class RegionalTree {
    private Long id;
    private String label;
    private Integer orgLevel;
    private Long parentId;
    private RegionalTree parent;
    private List<RegionalTree> children = new ArrayList<>();

    //get 和set方法省略
}

向上递归

 <select id="findXXX" parameterType="java.lang.Long" resultMap="findParentMap">
        SELECT *
        FROM tb_regional
        WHERE code = #{code,jdbcType=BIGINT}
    </select>

    <resultMap type="com.xx.bean.RegionalTree" id="findParentMap">
        <id column="code" property="id"/>
        <result column="regioname" property="label"/>
        <result column="level" property="orgLevel"/>
        <result column="parentcode" property="parentId"/>
        <collection property="parent" column="parentcode" ofType="com.xx.bean.RegionalTree" select="findByChildId"/>
    </resultMap>

    <select id="findByChildId" parameterType="java.lang.Long" resultMap="findParentMap">
        SELECT *
        FROM tb_regional
        WHERE code = #{parentcode,jdbcType=BIGINT}
    </select>

向下递归

<select id="findParent" parameterType="java.lang.Long" resultMap="menuMap">
        SELECT *
        FROM tb_regional
        WHERE code = #{code,jdbcType=BIGINT}
    </select>

    <resultMap type="com.xx.bean.RegionalTree" id="menuMap">
        <id column="code" property="id"/>
        <result column="regioname" property="label"/>
        <result column="level" property="orgLevel"/>
        <collection property="children" column="code" ofType="com.xx.bean.RegionalTree" select="findByParentId"/>
    </resultMap>

    <select id="findByParentId" parameterType="java.lang.Long" resultMap="menuMap">
        SELECT *
        FROM tb_regional
        WHERE parentcode = #{code,jdbcType=BIGINT}
    </select>

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