Linq to Sql
中文 | English
Originally not supporting IQueryable is mainly due to the consideration of usage habits. The intelligence of writing code will always prompt a bunch of methods you don't want to use. IQueryable itself provides a bunch of methods that cannot be implemented, as well as external intrusion extension methods, which seriously affect Coding experience. As shown below:
For FreeSql v1.4.0+ version, please use the following items to install with commands (old version does not need to be installed):
dotnet add package FreeSql.Extensions.Linq
-
Please try not to use the following Linq methods in
ISelectmode:GroupJoin,Select,SelectMany,JoinandDefaultIfEmpty. -
If you must use the
.Select()method inISelect, be sure to call it before.ToList().
FreeSql provides a powerful data query object: ISelect.
FreeSql.Extensions.Linq v1.4.0+ implements the common functions of IQueryable query objects for interactive use in various frameworks.
//Convert ISelect to IQueryable IQueryable<Student> queryable = fsql.Select<Student>().AsQueryable(); //Linq Query var t1 = queryable.Where(a => a.id == 1).FirstOrDefault(); //Restore IQueryable to ISelect ISelect<Studeng> select = queryable.RestoreToSelect();Note: The implementation of IQueryable does not currently support GroupBy. You can consider using the RestoreSelect method to switch back to ISelect for query.
var t1 = ( from a in fsql.Select<Student>() where a.id == item.id select a ).ToList();var t1 = ( from a in fsql.Select<Student>() where a.id == item.id select new { a.id } ).ToList();var t1 = ( from a in fsql.Select<Student>() where a.id == item.id select new { a.id, a.name, testsub = new { time = a.age > 10 ? "大于" : "小于或等于" } } ).ToList();var t1 = ( from a in fsql.Select<Student>() join b in fsql.Select<School>() on a.id equals b.StudentId select a ).ToList(); var t2 = ( from a in fsql.Select<Student>() join b in fsql.Select<School>() on a.id equals b.StudentId select new { a.id, bid = b.id } ).ToList(); var t3 = ( from a in fsql.Select<Student>() join b in fsql.Select<School>() on a.id equals b.StudentId where a.id == item.id select new { a.id, bid = b.id } ).ToList();var t1 = ( from a in fsql.Select<Student>() join b in fsql.Select<School>() on a.id equals b.StudentId into temp from tc in temp.DefaultIfEmpty() select a ).ToList(); var t2 = ( from a in fsql.Select<Student>() join b in fsql.Select<School>() on a.id equals b.StudentId into temp from tc in temp.DefaultIfEmpty() select new { a.id, bid = tc.id } ).ToList(); var t3 = ( from a in fsql.Select<Student>() join b in fsql.Select<School>() on a.id equals b.StudentId into temp from tc in temp.DefaultIfEmpty() where a.id == item.id select new { a.id, bid = tc.id } ).ToList();var t1 = ( from a in fsql.Select<Student>() from b in fsql.Select<School>() where a.id == b.StudentId select a ).ToList(); var t2 = ( from a in fsql.Select<Student>() from b in fsql.Select<School>() where a.id == b.StudentId select new { a.id, bid = b.id } ).ToList(); var t3 = ( from a in fsql.Select<Student>() from b in fsql.Select<School>() where a.id == b.StudentId where a.id == item.id select new { a.id, bid = b.id } ).ToList();var t1 = ( from a in fsql.Select<Student>() where a.id == item.id group a by new {a.id, a.name } into g select new { g.Key.id, g.Key.name, cou = g.Count(), avg = g.Avg(g.Value.age), sum = g.Sum(g.Value.age), max = g.Max(g.Value.age), min = g.Min(g.Value.age) } ).ToList();