Farseer.net Lightweight Open Source Framework primer: query data in detail

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Several ways to query a list

1         // field value specified plus 1 2         1). ToList ();

1         // Query the first 10 data 2         Users.Data.ToList (ten);

1         // Bulk Query 2         var New list<int12345  }; 3         Users.Data.ToList (LST);

1         // Query 2nd page, show 20 per page (page) 2         Users.Data.ToList (2);

1         // Query 5th page, show 10 per page (page) 2         int recordCount;    // Total Records 3         Users.Data.ToList (out5);

1         // reduce database pressure, show only username, password fields 2         New {o.username, O.password}). ToList ();

1         //Fuzzy search + Advanced Search2         varKeywords ="";3         varBean = Users.data;//can also be: var bean = User.Data.Select (o = = new {o.username, o.password})4Bean. Where (o = o.id >1);5         if(keywords. Ishaving ()) {bean. Where (o = o.username.contains (keywords)); }//Fuzzy Search When keywords has value6         //actions that can be added to or7Bean. Whereor (o = O.roleid = =2);8         varLST = Bean. ToList ();

1         // If you're too tolist slow (reflection to an entity, you can return only a DataTable 2         Users.Data.ToTable ();

1         // bulk queries, descending by ID 2         Users.Data.Desc (o = o.id). ToList (); 3 4         // batch query, by ID, UserName ascending 5         New {o.id,o.username}). ToList ();

1         // return random Records 2         Users.Data.ToListByRand ();

1         // The result returned here is not an entity, it is a list of identity IDs.  2         //  For example, the possible return is: 1,2,3,43         Users.Data.ToSelectList ();

Several ways to query a single record

1         // find a single record of id = = 1 2         Users.Data.ToInfo (1);

1         // next piece of data with ID 1 (usually the concept of the next article) 2         Users.Data.ToNextInfo (1);

1         // previous data with ID 2 (usually the concept of the previous article) 2         Users.Data.ToPreviousInfo (2);

Several ways to query single values and aggregation

1         // total number of records returned 2         6). Count ();

1         // returns the maximum ID 2         Users.Data.GetMax (o = o.id);

1         // returns the minimum number of IDs 2         Users.Data.GetMin (o = o.id);

1         // returns the cumulative number of IDs 2         Users.Data.GetSum (o = o.id);

1         // returns the user name (here is the string type)2         Users.Data.GetValue (o = o.username);

1         // determine if a value exists 2         1). Ishaving ();

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Previous: Farseer.net lightweight open source framework Getting started: deleting data in detail

Farseer.net Lightweight Open Source Framework primer: query data in detail