效果如图，姓名 数值1 字段进行自动合并

封装合并列js - tableMerge.js

// 获取列合并的行数
// params
// tableData: 表格数据
// mergeId: 合并的列的字段名
export const tagRowSpan = (tableData, mergeId) =>{
  const tagArr = [];
  let pos = 0;
  tableData.map((item, index) => {
    if (index === 0) {
      tagArr.push(1);
      pos = 0;
    } else if (tableData[index][mergeId] === tableData[index - 1][mergeId]) {
      // 合并项目
      tagArr[pos] += 1;
      tagArr.push(0);
    } else {
      tagArr.push(1);
      pos = index;
    }
  });
  return tagArr;
}
// 列方法
export const handleSpanMethod  = ({ rowIndex, columnIndex, column }, tagArr, needMergeCol) => {
  if (needMergeCol.includes(columnIndex)) {
    const _row = tagArr[column.property][rowIndex];
    const _col = _row > 0 ? 1 : 0;
    return {
      rowspan: _row,
      colspan: _col,
    };
  }
}

拖拽使用sortablejs

npm install sortablejs -S

使用实例

如果拖拽列 要动态生成列

<template>
  <el-table :data="tableData.data" border style="width: 100%; margin-top: 20px"
            :span-method="(param) => handleSpanMethod(param, tableData.spanMap, needMergeCol)" ref="dragTable" >
    <el-table-column :prop="col.prop" :label="col.label" v-for="(col, index) in colData" :key="col.prop + index">
    </el-table-column>

  </el-table>
</template>

<script>
import Sortable from 'sortablejs'
import { tagRowSpan ,handleSpanMethod} from '@/utils/tableMerge.js'
export default {
  data () {
    return {
      colData: [
        {
          prop: 'name',
          label: '姓名'
        },
        {
          prop: 'id',
          label: 'ID',
          width: '180'
        },
        {
          prop: 'amount1',
          label: '数值 1（元）'
        },
        {
          prop: 'amount2',
          label: '数值 2（元）'
        },
        {
          prop: 'amount3',
          label: '数值 3（元）'
        }
      ],
      tableData: {
        data: [{
          id: '1',
          name: '王小虎1',
          amount1: '234',
          amount2: '3.2',
          amount3: 10
        }, {
          id: '2',
          name: '王小虎1',
          amount1: '234',
          amount2: '4.43',
          amount3: 12
        }, {
          id: '3',
          name: '王小虎1',
          amount1: '324',
          amount2: '1.9',
          amount3: 9
        }, {
          id: '4',
          name: '王小虎4',
          amount1: '621',
          amount2: '2.2',
          amount3: 17
        }, {
          id: '5',
          name: '王小虎5',
          amount1: '539',
          amount2: '4.1',
          amount3: 15
        }],
        mergeField: ['name','amount1'],
        //存储字段合并的行数
        spanMap: {},
      },
    };
  },
  methods: {
    handleSpanMethod,
    columnDrop () {
      const wrapperTr = document.querySelector('.el-table__header-wrapper tr')
      Sortable.create(wrapperTr, {
        animation: 180,
        delay: 0,
        onEnd: evt => {
          let value = this.colData
          const oldItem = value[evt.oldIndex]
          value.splice(evt.oldIndex, 1)
          value.splice(evt.newIndex, 0, oldItem)
        }
      })
    },
    init () {
      this.tableData.mergeField.forEach(item => {
        this.tableData.spanMap[item] = tagRowSpan(this.tableData.data, item);
      })
    }
  },
  computed: {
    needMergeCol () {
      return this.tableData.mergeField.map(item => {
        return this.colData.findIndex(col => col.prop === item)
      })
    }
  },
  mounted () {
    document.body.ondrop = function (event) {
      event.preventDefault(); //用于取消事件的默认行为，比如拒绝拖拽元素的默认行为；
      event.stopPropagation(); //用于阻止事件冒泡，避免出现多重事件响应
    }
    this.init()
    this.$nextTick(() => {
      this.columnDrop()
    })
  },
};
</script>

注意不支持行拖拽