datarelation

how to add a relationship between tables in the dataset

由 北城余情 提交于 2019-12-25 03:55:55
问题 I have the following code to get the get the relationship between the tables in the same dataset , but when run the following code i encounter with error saying , these columns currently dont have unique values DataResultSetDataSet dataset = resultSet as DataResultSetDataSet; System.Data.DataSet menuDataSet = new System.Data.DataSet(); menuDataSet = dataset.Set; menuDataSet.DataSetName = "Menus"; menuDataSet.Tables[0].TableName = "Menu"; DataRelation relation = new DataRelation("ParentChild",

How do I update a list data_relation in Python Eve

由 て烟熏妆下的殇ゞ 提交于 2019-12-12 04:54:14
问题 I have a model 'users' and a schema for it, which includes a one-to-many relation back to users: 'followers': { 'type': 'list', 'schema': { 'type': 'objectid', 'data_relation': { 'resource': 'users' } } }, I am trying to update the list of followers. I tried sending PATCH request to the /users/545c7dccb505970bbf0e5ad1 endpoint with a 'followers' key and a list of objectids but it doesn't work. Also tried sending a PUT request to /users/545c7dccb505970bbf0e5ad1/followers/ but no luck. So how

DataRelation: How to compare specific columns

由 ☆樱花仙子☆ 提交于 2019-12-11 18:26:44
问题 I am comparing two datatables using the answer in this link Compare two Datatables but when I use the DataRelation function I am getting an error that both columns length should match. but I want to only compare specific columns. Currently I have it this way: // Using a Dataset to make use of a DataRelation Object using (DataSet ds = new DataSet()) { //Add Tables ds.Tables.AddRange(new DataTable[] { dt.Copy(), dataTable.Copy() }); //Get First Columns for DataRelation DataColumn[] firstcolumns

LINQ - How can I use DataSet.DataRelation to join these tables and sum one field?

由 与世无争的帅哥 提交于 2019-12-11 04:49:47
问题 My LINQ query is not producing the expected output below. Basically, it's the sum of table3.cost corresponding to table2.code and table2.class categorized by table1.alias and ordered by table1.priority. I added two DataRelation's to the DataSet: ds.Relations.Add("Table1Table2", ds.Tables[1].Columns("ID"), ds.Tables[2].Columns("ParentID"); ds.Relations.Add("Table2Table3", new DataColumn[] { ds.Tables[2].Columns["Code"], ds.Tables[2].Columns["Class"] }, new DataColumn[] { ds.Tables[3].Columns[

Does LINQ use DataRelations to optimize joins?

由 谁都会走 提交于 2019-12-07 03:11:27
问题 I can't find the answer to this anywhere, and before I start pawing through generated code with Reflector I thought it'd be worth asking: Suppose I have the following LINQ query run against DataTables in a DataSet: var list = from pr in parentTable.AsEnumerable() join cr in childTable.AsEnumerable() on cr.Field<int>("ParentID") equals pr.Field<int>("ID") where pr.Field<string>("Value") == "foo" select cr; If there's a DataRelation between the parent table and the child table that uses the key

Does LINQ use DataRelations to optimize joins?

由 梦想与她 提交于 2019-12-05 06:32:34
I can't find the answer to this anywhere, and before I start pawing through generated code with Reflector I thought it'd be worth asking: Suppose I have the following LINQ query run against DataTables in a DataSet: var list = from pr in parentTable.AsEnumerable() join cr in childTable.AsEnumerable() on cr.Field<int>("ParentID") equals pr.Field<int>("ID") where pr.Field<string>("Value") == "foo" select cr; If there's a DataRelation between the parent table and the child table that uses the key fields shown, will LINQ use it? That is, will it find the rows in the parent table for which Value is

How To: Use DataRelation to perform a join on two DataTables in a DataSet?

由 限于喜欢 提交于 2019-11-28 12:46:30
How do I perform a join between two DataTables in a Dataset? I created a DataRelation between two tables….then what? I'm looking at one explanation on how to do it ( http://www.emmet-gray.com/Articles/DataTableJoins.htm ) which involves copying rows from tables to a result table? Is there a better way to do this? See if this helps DataTable person = new DataTable(); person.Columns.Add("Id"); person.Columns.Add("Name"); DataTable pet = new DataTable(); pet.Columns.Add("Id"); pet.Columns.Add("Name"); pet.Columns.Add("OwnerId"); DataSet ds = new DataSet(); ds.Tables.AddRange(new[] { person, pet }

How To: Use DataRelation to perform a join on two DataTables in a DataSet?

由 て烟熏妆下的殇ゞ 提交于 2019-11-27 07:15:59
问题 How do I perform a join between two DataTables in a Dataset? I created a DataRelation between two tables….then what? I'm looking at one explanation on how to do it (http://www.emmet-gray.com/Articles/DataTableJoins.htm) which involves copying rows from tables to a result table? Is there a better way to do this? 回答1: See if this helps DataTable person = new DataTable(); person.Columns.Add("Id"); person.Columns.Add("Name"); DataTable pet = new DataTable(); pet.Columns.Add("Id"); pet.Columns.Add
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