Updating recursive xml views of relations missdating ru

27-Mar-2020 11:56

FROM Specifies that a table, view, or derived table source is used to provide the criteria for the update operation. If the object being updated is the same as the object in the FROM clause and there is only one reference to the object in the FROM clause, an object alias may or may not be specified.

If the object being updated appears more than one time in the FROM clause, one, and only one, reference to the object must not specify a table alias.

Note Any call to OPENDATASOURCE, OPENQUERY, or OPENROWSET in the FROM clause is evaluated separately and independently from any call to these functions used as the target of the update, even if identical arguments are supplied to the two calls. Avoid using these hints in this context in new development work, and plan to modify applications that currently use them.

In particular, filter or join conditions applied on the result of one of those calls have no effect on the results of the other. Table2; USE Adventure Works2012; GO IF OBJECT_ID ('dbo. All char and nchar columns are right-padded to the defined length.

the latency to the database server), and therefore the best option is to execute a single query that brings back all of the data you need in one go rather than separate queries for each individual entity. your ing the relevant navigation properties you still find your query is taking too long to execute you should look at the execution plan of the query to see where the performance problem lies.

Post another question if you need help analyzing it.

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For more information, see OUTPUT Clause (Transact-SQL).As you already seem to be aware Entity Framework by default lazy-loads all navigation properties by creating a dynamic proxy object around them. you follow the navigation property) then it issues a query to the database to actually go off and fetch the data.The reason that this has a performance impact is that each database query that gets executed has a certain overhead associated with it (e.g.Common table expressions can also be used with the SELECT, INSERT, DELETE, and CREATE VIEW statements.

For more information, see WITH common_table_expression (Transact-SQL). For information about table hints, see Table Hints (Transact-SQL).This can also be used to change the column to NULL if the column has no default and is defined to allow null values.