项目场景：

简单记录一些Mybatis构造的常用sql写法，仅做为笔记记录，无其他作用。

1.数据插入通过map传参，灵活插入表格数据

<insert id="saveExportRecord">
        insert into ${downloadTable}
        <foreach collection="recordMap.keys" item="key" open="(" close=")"
                 separator=",">
            ${key}
        </foreach>
        values
        <foreach collection="recordMap.values" item="value" open="("
                 close=")" separator=",">
            #{value}
        </foreach>
    </insert>

2. 构造where条件

List<Map> selectMapsPage(@Param(Constants.WRAPPER) Wrapper query, @Param("tableName") String tableName);

<select id="selectMapsPage" resultType="java.util.Map" parameterType="java.util.Map">
        SELECT *
        FROM ${tableName}
        <if test="ew.emptyOfWhere == false">
            ${ew.customSqlSegment}
        </if>
    </select>

3.构造where条件和sql语句where条件混用1

    /**
     * 根据自定义sql查询
     * @param query
     * @param tableName
     * @param fields
     * @param joinCustomSqlSql
     * @param orderBySql
     * @return
     */
    List<Map> selectListByCustomSql(@Param(Constants.WRAPPER) Wrapper query, @Param("tableName") String tableName, @Param("fields") String fields, @Param("joinCustomSqlSql") String joinCustomSqlSql, @Param("orderBySql") String orderBySql);

   <select id="selectListByCustomSql" resultType="java.util.Map" parameterType="java.util.Map">
        SELECT ${fields}
        FROM ${tableName}
        <if test="ew.emptyOfWhere == false">
            <where>
                ${joinCustomSqlSql}
                <if test="ew.customSqlSegment != null and ew.customSqlSegment.startsWith('WHERE')">
                    AND
                </if>
                ${ew.sqlSegment}
            </where>
        </if>
        order by ${orderBySql}
    </select>

4.构造where条件和sql语句where条件混用2

List<Map> paymentList(@Param(Constants.WRAPPER) Wrapper query, @Param("examId") String examId);

<select id="paymentList" resultType="java.util.Map" parameterType="java.lang.String">
        SELECT a.`ORDNO`, a.`ORDAMT`
        FROM `exam_${examId}_examinee` a,`exam_config` cg
        <if test="ew.emptyOfWhere == false">
            <where>
                a.SS = cg.department_code
                AND cg.examid = #{examId}
                <if test="ew.customSqlSegment != null and ew.customSqlSegment.startsWith('WHERE')">
                    AND
                </if>
                ${ew.sqlSegment}
            </where>
        </if>
    </select>