el-table合计行怎么合并?

<el-table size="small" :header-cell-style="{'text-align':'center'}"
                    :cell-style="{'text-align':'center'}" :data="top1tableData" height="100%"
                    :span-method="objectSpanMethod">
                    <el-table-column type="selection" width="55" fixed="left"></el-table-column>
                    <el-table-column prop="0" label="公司" min-width="150" fixed="left"></el-table-column>
                    <el-table-column prop="1" label="地理位置" fixed="left"></el-table-column>
                    <el-table-column prop="2" label="名称" fixed="left"></el-table-column>
                    <el-table-column prop="3" label="状态" fixed="left"></el-table-column>
                    <el-table-column label="上网电量">
                        <el-table-column prop="" label="日计划上网电量">
                            <el-table-column prop="4" label="营销"></el-table-column>
                            <el-table-column prop="5" label="内控"></el-table-column>
                        </el-table-column>
                        <el-table-column prop="6" label="日实际上网电量"></el-table-column>
                        <el-table-column prop="7" label="月累计"></el-table-column>
                        <el-table-column prop="8" label="年累计"></el-table-column>
                    </el-table-column>
                    <el-table-column prop="" label="发电量(万千瓦时)">
                        <el-table-column prop="" label="日计划发电量">
                            <el-table-column prop="9" label="营销"></el-table-column>
                            <el-table-column prop="10" label="内控"></el-table-column>
                        </el-table-column>
                        <el-table-column prop="11" label="日实际发电量"></el-table-column>
                        <el-table-column prop="12" label="负荷率(%)"></el-table-column>
                        <el-table-column prop="" label="月计划发电量">
                            <el-table-column prop="13" label="营销"></el-table-column>
                            <el-table-column prop="14" label="内控"></el-table-column>
                        </el-table-column>
                        <el-table-column prop="15" label="月累计"></el-table-column>
                        <el-table-column prop="16" label="年计划"></el-table-column>
                        <el-table-column prop="17" label="年累计"></el-table-column>
                    </el-table-column>
                    <el-table-column label="操作" fixed="right" width="150">
                        <template slot-scope="scope">
                            <el-button size="mini" type="success" v-if="scope.row[3]!='已审核'"
                                @click="approved(scope.row)">通过</el-button>
                            <el-button size="mini" type="danger">驳回</el-button>
                        </template>
                    </el-table-column>
                </el-table>

objectSpanMethod({
                row,
                column,
                rowIndex,
                columnIndex
            }) {
                
                if (columnIndex === 2 && row[columnIndex] === '合计') {
                    return {
                        rowspan: 1,
                        colspan: 2
                    };
                }


            },

我这样写了过后数据是错位的

请问应该怎么处理合并?