瞭望岛

Linq组合查询和模糊查询。组合查询先组合出IQueryable语句，再执行查询；模糊查询使用Contains()，StartsWith()，EndsWith()等方法。

Linq组合查询：

DataClasses1DataContext db= new DataClasses1DataContext();
var query = db.Users.AsQueryable();//用户表
if (!string.IsNullOrEmpty(username))
{

    query =query.Where(c => c.UserName == username);
}

if (!string.IsNullOrEmpty(nickname))
{

    query = query.Where(c =>c.NickName == nickname);
}
var list = query.ToList();

Linq模糊查询：

DataClasses1DataContext db= new DataClasses1DataContext();

var query = db.Users.AsQueryable();//用户表

//等于
query = query.Where(c => c.UserName == username);

//like %username%
query = query.Where(c => c.UserName.Contains(username));

//like username%
query = query.Where(c => c.UserName.StartsWith(username));

//like %username
query = query.Where(c => c.UserName.EndsWith(username));

//出现位置
query = query.Where(c =>c.UserName.IndexOf(username) > 0);

var list = query.ToList();