如何从查询中获取前1条记录

Question

假设查询中有5条记录,如何获得前1条记录？这是我目前的代码.

public Application GetByUserIdAndVersion(int userId, string version)
{
    VettingDataContext dc = new VettingDataContext(_connString);
    return (from a in dc.Applications
            where a.UserId == userId && a.chr_Version == version
            select a).SingleOrDefault<Application>();
}

Answer 1

只需使用FirstOrDefault():

return (from a in dc.Applications
        where a.UserId == userId && a.chr_Version == version
        select a).FirstOrDefault<Application>();

SingleOrDefault()如果有多个记录,则会抛出异常,FirstOrDefault()只会占用第一个记录.

此外,你不应该强制转换Application- 你的记录已经是类型Application.