在ADFv2中，如果遇到列映射问题，可以通过使用数据流活动和映射数据流来解决。下面是一个包含代码示例的解决方法：

1. 创建一个数据流活动，为其指定输入和输出数据集。

{
    "name": "DataFlowActivity",
    "type": "Microsoft.DataFactory/factories/pipelines/activities",
    "dependsOn": [
        {
            "activity": "[concat('CopyActivity_', pipeline().parameters.inputDataset)]",
            "dependencyConditions": [
                "Succeeded"
            ]
        }
    ],
    "policy": {
        "timeout": "7.00:00:00",
        "retry": 0,
        "retryIntervalInSeconds": 30,
        "secureOutput": false
    },
    "userProperties": [],
    "typeProperties": {
        "streamingUnits": 1,
        "dataflow": {
            "referenceName": "MyDataFlow",
            "type": "MappingDataFlow"
        },
        "source": {
            "type": "DatasetReference",
            "referenceName": "InputDataset"
        },
        "sink": {
            "type": "DatasetReference",
            "referenceName": "OutputDataset"
        }
    }
}

2. 在数据流活动中，指定列映射规则。

{
    "name": "MyDataFlow",
    "properties": {
        "type": "MappingDataFlow",
        "typeProperties": {
            "sources": [
                {
                    "dataset": {
                        "referenceName": "InputDataset",
                        "type": "DatasetReference"
                    },
                    "name": "Source"
                }
            ],
            "sinks": [
                {
                    "dataset": {
                        "referenceName": "OutputDataset",
                        "type": "DatasetReference"
                    },
                    "name": "Sink"
                }
            ],
            "transformations": [
                {
                    "name": "ColumnMapping",
                    "properties": {
                        "type": "Mapping",
                        "typeProperties": {
                            "source": {
                                "type": "TabularTranslator",
                                "mappings": [
                                    {
                                        "sourceColumnName": "SourceColumn1",
                                        "sinkColumnName": "SinkColumn1"
                                    },
                                    {
                                        "sourceColumnName": "SourceColumn2",
                                        "sinkColumnName": "SinkColumn2"
                                    },
                                    ...
                                ]
                            },
                            "sink": {
                                "type": "TabularTranslator"
                            }
                        }
                    }
                }
            ]
        }
    }
}

3. 在列映射规则中，指定源列和目标列之间的映射关系。根据实际情况，添加所有需要映射的列。

以上示例中，我们假设有两个输入列（SourceColumn1和SourceColumn2）和两个输出列（SinkColumn1和SinkColumn2）。你可以根据你的实际需求，添加或修改列映射规则。

请注意，示例代码中的数据集（InputDataset和OutputDataset）需要根据你的实际情况进行替换。

这是ADFv2中解决列映射问题的一个基本方法，你可以根据实际需求进行修改和扩展。