vue+elementui前端分页展示且需要根据指定字段合并单元格，后端需要指定pagehelper分页插件分页位置

在Vue中使用Element UI进行前端分页，并需要根据指定字段合并单元格，你可以使用Element UI的<el-table>组件的span-method属性来实现合并单元格的逻辑。后端需要使用PageHelper进行分页处理。

以下是一个简单的示例：

<template>
  <div>
    <el-table :data="tableData" border style="width: 100%" :span-method="mergeCells">
      <el-table-column prop="date" label="日期" width="150"></el-table-column>
      <el-table-column prop="name" label="姓名" width="150"></el-table-column>
      <el-table-column prop="address" label="地址" width="300"></el-table-column>
    </el-table>
    <el-pagination
      @size-change="handleSizeChange"
      @current-change="handleCurrentChange"
      :current-page="currentPage"
      :page-sizes="[10, 20, 30, 40]"
      :page-size="pageSize"
      layout="total, sizes, prev, pager, next, jumper"
      :total="total">
    </el-pagination>
  </div>
</template>
 
<script>
export default {
  data() {
    return {
      tableData: [],
      currentPage: 1,
      pageSize: 10,
      total: 0,
      mergeField: 'name', // 指定合并字段
      mergeQueue: []
    };
  },
  methods: {
    fetchData() {
      // 模拟发起请求获取分页数据
      // 假设res.data中包含total和list字段
      axios.get('/api/data', {
        params: {
          page: this.currentPage,
          pageSize: this.pageSize
        }
      }).then(res => {
        this.tableData = res.data.list;
        this.total = res.data.total;
      });
    },
    handleSizeChange(val) {
      this.pageSize = val;
      this.fetchData();
    },
    handleCurrentChange(val) {
      this.currentPage = val;
      this.fetchData();
    },
    mergeCells({ row, column, rowIndex, columnIndex }) {
      if (column.property === this.mergeField) {
        if (this.mergeQueue.length === 0) {
          this.mergeQueue.push({
            index: rowIndex,
            value: row[this.mergeField]
          });
        } else {
          const last = this.mergeQueue[this.mergeQueue.length - 1];
          if (last.value === row[this.mergeField]) {
            this.mergeQueue.push({
              index: rowIndex,
              value: row[this.mergeField]
            });
          } else {
            const span = this.mergeQueue.length;
            this.mergeQueue = [{ index: rowIndex, value: row[this.mergeField] }];
            return [span, 1];
          }
        }
      }