【数据存储】合服的数据迁移：角色合并与冲突处理

---合服迁移：ID 重映射与重名处理
function Merge.run(srcDb, dstDb)
    local idMap = {}
    for _, role in ipairs(srcDb.query("SELECT * FROM roles")) do
        local newId = Merge.nextId()
        idMap[role.id] = newId
        -- 重名检测：加服名后缀
        if Merge.nameExists(dstDb, role.name) then
            role.name = role.name .. "@" .. Merge.srcTag()
            sendmail(role.name, 8009, "合服改名通知",
                "您的名字与另一位玩家重复，已自动调整", "")
        end
        dstDb.exec("INSERT INTO roles SET ?", role)
    end
    Merge.saveIdMap(idMap)
end

---背包与邮件的 ID 改写
function Merge.remap(idMap)
    -- 背包的归属改写
    for oldId, newId in pairs(idMap) do
        dstDb.exec("UPDATE bags SET uid = ? WHERE uid = ?",
            newId, oldId)
    end
    -- 邮件的收发双方改写
    dstDb.exec("UPDATE mails SET toId = ? WHERE toId = ?",
        function(row) return idMap[row.toId] or row.toId end)
    -- 行会成员的归属改写
    Merge.remapGuildMembers(idMap)
end