Improve this question. Add a comment. Active Oldest Votes. Improve this answer. For example, a view can be used for the following purposes: To focus, simplify, and customize the perception each user has of the database. To provide a backward compatible interface to emulate a table whose schema has changed.
Justin Pihony Justin Pihony That is the most rational explanation I've heard for prohibiting parameterized views. Still stinks, though, when you need parameters to filter subqueries. Craig Craig 3 1 1 bronze badge. While you were being condescending, you missed the fact that you created a stored procedure, not a view. Sign up or log in Sign up using Google.
Skipping a parameter means sending a similar request:. If the content of the Value node is empty, the parameter PriceLimit is passed as an empty string. Sql; using System. Add " monthNo", System.
Int ; cmd. Parameters[" monthNo"]. Add " minAmount", System. Decimal ; cmd. Parameters[" minAmount"]. ExecuteReader ; while reader. Related Articles. Simple process to track and log SQL Server stored procedure use. Finding SQL Server objects that reference invalid objects. Popular Articles. Rolling up multiple rows into a single row and column for SQL Server data. How to tell what SQL Server versions you are running. Resolving could not open a connection to SQL Server errors.
Ways to compare and find differences for SQL Server tables and data. Searching and finding a string value in all columns in a SQL Server table.
The previous example could also be done with queries like these:. This happens because listchildren returns an empty set for those arguments, so no result rows are generated. Any extra rows produced by the RETURNING clause are silently dropped, but the commanded table modifications still happen and are all completed before returning from the function. Note: The key problem with using set-returning functions in the select list, rather than the FROM clause, is that putting more than one set-returning function in the same select list does not behave very sensibly.
What you actually get if you do so is a number of output rows equal to the least common multiple of the numbers of rows produced by each set-returning function. SQL functions can be declared to accept and return the polymorphic types anyelement , anyarray , anynonarray , anyenum , and anyrange. See Section Notice the use of the typecast 'a'::text to specify that the argument is of type text. This is required if the argument is just a string literal, since otherwise it would be treated as type unknown , and array of unknown is not a valid type.
Without the typecast, you will get errors like this:. It is permitted to have polymorphic arguments with a fixed return type, but the converse is not. When a SQL function has one or more parameters of collatable data types, a collation is identified for each function call depending on the collations assigned to the actual arguments, as described in Section If a collation is successfully identified i.
This will affect the behavior of collation-sensitive operations within the function. For example, using the anyleast function described above, the result of. In C locale the result will be ABC , but in many other locales it will be abc.
Alternatively, if you wish a function to operate with a particular collation regardless of what it is called with, insert COLLATE clauses as needed in the function definition.
If no common collation can be identified among the actual arguments, then a SQL function treats its parameters as having their data types' default collation which is usually the database's default collation, but could be different for parameters of domain types. The behavior of collatable parameters can be thought of as a limited form of polymorphism, applicable only to textual data types. Development Versions: devel.
Unsupported versions: 9. This documentation is for an unsupported version of PostgreSQL. You may want to view the same page for the current version, or one of the other supported versions listed above instead.
PostgreSQL 9. Extending SQL Next. SQL Functions on Composite Types When writing functions with arguments of composite types, we must not only specify which argument we want but also the desired attribute field of that argument.
Note two important things about defining the function: The select list order in the query must be exactly the same as that in which the columns appear in the table associated with the composite type.
SQL Functions with Variable Numbers of Arguments SQL functions can be declared to accept variable numbers of arguments, so long as all the "optional" arguments are of the same data type.
Polymorphic SQL Functions SQL functions can be declared to accept and return the polymorphic types anyelement , anyarray , anynonarray , anyenum , and anyrange. Without the typecast, you will get errors like this: ERROR: could not determine polymorphic type because input has type "unknown" It is permitted to have polymorphic arguments with a fixed return type, but the converse is not.
Polymorphism can be used with functions that have output arguments. SQL Functions with Collations When a SQL function has one or more parameters of collatable data types, a collation is identified for each function call depending on the collations assigned to the actual arguments, as described in Section
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