Question

Like Oracle, SQL Server supports parameter defaults in stored procedures. Oracle syntax:

CREATE OR REPLACE PROCEDURE p_default (
  p_in_number   IN  number   := 0,
  p_out_number  OUT number,
  p_in_varchar  IN  varchar2 := '0',
  p_out_varchar OUT varchar2,
  p_in_date     IN  date     := date '1981-07-10',
  p_out_date    OUT date
)

SQL Server syntax:

CREATE PROCEDURE p_default (
  @p_in_number       INTEGER = 0,
  @p_out_number      INTEGER OUT,
  @p_in_varchar      VARCHAR(10) = '0',
  @p_out_varchar     VARCHAR(10) OUT,
  @p_in_date         DATE = '1981-07-10',
  @p_out_date        DATE OUT
)

With Oracle, I can discover defaults using this query:

SELECT argument_name, defaulted FROM all_arguments WHERE object_id = :proc_id

How can I discover this in SQL Server selecting from sys or INFORMATION_SCHEMA tables? I don’t see any useful column in INFORMATION_SCHEMA.PARAMETERS, and the sys.parameters.has_default_value seems not to be set correctly (!)

Note, I have asked as similar question about DB2:

Discover DB2 procedure default parameters using SYSCAT tables

Answer 1

There’s no simple way to do it. As the documentation for has_default_value states:

SQL Server only maintains default values for CLR objects in this catalog view; therefore, this column has a value of 0 for Transact-SQL objects. To view the default value of a parameter in a Transact-SQL object, query the definition column of the sys.sql_modules catalog view, or use the OBJECT_DEFINITION system function.

So you’d have to pull the whole stored proc definition out and parse it yourself to determine the value.

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Side note: I’d be wary of @p_in_date DATE = '1981-07-10'. I know that the date datatype is a bit more sensible than datetime, but I’m not sure if the above is still ambiguous – certainly if it was converted to datetime, it may result in 10th July or 7th October, depending on language settings. I’d be more comfortable with '19810710' which will always be interpreted as 10th July.