Related
Background Information:
In Python, I might write something like this if I want to apply the same logic to different values in a list.
database_list = ["db_1", "db_2", "db_3"]
for x in range(0,len(database_list),1):
print("the database name is " + database_list[x])
What I am trying to do:
What I am trying to do in SSMS, is pull a list of DB objects for each database. I created a stored procedure to pull exactly what I want, but I have to run it against each database, so 10 databases mean running it 10 times.
My goal is to do this with a T-SQL query instead of Python.
I tried doing something like this:
exec sp_MSforeachdb 'USE ?; EXEC [dbo].[my_stored_procedure]';
The problem with this is, [dbo].[my_stored_procedure] has to exist in every database I want to do this in.
How can I create the stored procedure in 1 database, but execute it for all databases or a list of databases that I choose?
I know what you are trying to do and if it's what I think (you seem reluctant to actually say!) you can do the following:
In the master database, create your procedure. Normally you wouldn't do this, but in this case you must prefix it sp_
use master
go
create procedure sp_testproc as
select top 10 * from sys.tables
go
Now if you run this, it will return tables from the master database.
If you switch context to another database and exec master.dbo.sp_testproc, it will still return tables from the master database.
In master, run
sys.sp_MS_marksystemobject sp_testproc
Now switch context to a different database and exec master.dbo.sp_testproc
It will return tables from the database you are using.
Try creating your sproc in master and naming it with an sp_ prefix:
USE master
GO
CREATE PROCEDURE sp_sproc_name
AS
BEGIN
...
END
GO
-- You *may* need to mark it as a system object
EXEC sys.sp_MS_marksystemobject sp_sprocname
See: https://nickstips.wordpress.com/2010/10/18/sql-making-a-stored-procedure-available-to-all-databases/
It should then be available in all dbs
Create the stored procedure in the Master database with the sp_ prefix, and use dynamic SQL in the stored procedure so it resolves object names relative to the current database, rather than the database which contains the stored procedure.
EG
use master
go
CREATE OR ALTER PROCEDURE [dbo].[sp_getobjects]
AS
exec ('
select *
from [sys].[objects]
where is_ms_shipped = 0
order by type, name
')
go
use AdventureWorks2017
exec sp_getobjects
#LunchBox - it's your single stored procedure (that you create in one database) that is actually going to need to contain the "exec sp_MSforeach ...." command, and instead of the command to be executed being "EXEC ", it will need to be the actual SQL that you were going to put into the stored proc.
Eg. (inside your single stored procedure)
EXEC sp_MSforeachdb 'USE ?; SELECT * FROM <table>; UPDATE <another table> SET ...';
Think of the stored procedure (that you put into one database) as being no different than your Python code file - if you had actually wanted to achieve the same thing in Python, you would have either needed to create the stored proc in each database, or build the SQL statement string in Python and execute it against each database.
I understand what you thought you might be able to achieve with SQL, but stored procedures really don't work the way you were expecting. Even when you're in the context of a different database, but you run EXEC <different_db>.stored_proc, that stored proc ends up running in the context of the database in which it exists (not your context database).
Now, the only one issue you may come up against is that the standard sp_MSforeachdb stored proc has a limit of 2000 characters for the command that can be executed (although, it does have multiple "command" parameters, this may not be practical if you were planning on running a very large code block, perhaps with variables that carry all the way through). If this is something that might impact what you're intending to do, you could do a search online for "sp_MSforeachdb alternatives" - there seem to be a handful that people have created where the command parameter can contain a larger string.
I'm trying to execute a SQL Server stored procedure through Python Pyodbc and to get the selection results printed out into .csv files. But this procedure is currently being used in other daily tasks so I'm worried that if my executing the procedure in python will interrupt the daily scheduled job process in SQL Server Agent. In the procedure, it creates several temporary tables #temp_a, #temp_b, and #temp_c. I'm wondering if these temp tables will break the scheduled jobs that include this procedure since there might be other procedures that will be creating temp table names using the same name such as #temp_a or #temp_b. The temp tables are created inside the procedure but with no delete query written. I could have tested this myself but the database I'm working on right now is just so fragile that I was told not to create tests. Thanks!
Yes
The temp-Tables will be created per Session.
I got the procedure execute by different Sessions on the same time there will be the same count of the temp-tables as sessions executed.
This temp-tables have each a different name:
#V_...._000000003EB1
#V_...._000000003EB8
The example above are the temp-Tables created by the same Procedure executed two times by different sessions at the same time.
So your scenario couldn't happen
I have three stored procedures Sp1, Sp2 and Sp3.
The first one (Sp1) will execute the second one (Sp2) and save returned data into #tempTB1 and the second one will execute the third one (Sp3) and save data into #tempTB2.
If I execute the Sp2 it will work and it will return me all my data from the Sp3, but the problem is in the Sp1, when I execute it it will display this error:
INSERT EXEC statement cannot be nested
I tried to change the place of execute Sp2 and it display me another error:
Cannot use the ROLLBACK statement
within an INSERT-EXEC statement.
This is a common issue when attempting to 'bubble' up data from a chain of stored procedures. A restriction in SQL Server is you can only have one INSERT-EXEC active at a time. I recommend looking at How to Share Data Between Stored Procedures which is a very thorough article on patterns to work around this type of problem.
For example a work around could be to turn Sp3 into a Table-valued function.
This is the only "simple" way to do this in SQL Server without some giant convoluted created function or executed sql string call, both of which are terrible solutions:
create a temp table
openrowset your stored procedure data into it
EXAMPLE:
INSERT INTO #YOUR_TEMP_TABLE
SELECT * FROM OPENROWSET ('SQLOLEDB','Server=(local);TRUSTED_CONNECTION=YES;','set fmtonly off EXEC [ServerName].dbo.[StoredProcedureName] 1,2,3')
Note: You MUST use 'set fmtonly off', AND you CANNOT add dynamic sql to this either inside the openrowset call, either for the string containing your stored procedure parameters or for the table name. Thats why you have to use a temp table rather than table variables, which would have been better, as it out performs temp table in most cases.
OK, encouraged by jimhark here is an example of the old single hash table approach: -
CREATE PROCEDURE SP3 as
BEGIN
SELECT 1, 'Data1'
UNION ALL
SELECT 2, 'Data2'
END
go
CREATE PROCEDURE SP2 as
BEGIN
if exists (select * from tempdb.dbo.sysobjects o where o.xtype in ('U') and o.id = object_id(N'tempdb..#tmp1'))
INSERT INTO #tmp1
EXEC SP3
else
EXEC SP3
END
go
CREATE PROCEDURE SP1 as
BEGIN
EXEC SP2
END
GO
/*
--I want some data back from SP3
-- Just run the SP1
EXEC SP1
*/
/*
--I want some data back from SP3 into a table to do something useful
--Try run this - get an error - can't nest Execs
if exists (select * from tempdb.dbo.sysobjects o where o.xtype in ('U') and o.id = object_id(N'tempdb..#tmp1'))
DROP TABLE #tmp1
CREATE TABLE #tmp1 (ID INT, Data VARCHAR(20))
INSERT INTO #tmp1
EXEC SP1
*/
/*
--I want some data back from SP3 into a table to do something useful
--However, if we run this single hash temp table it is in scope anyway so
--no need for the exec insert
if exists (select * from tempdb.dbo.sysobjects o where o.xtype in ('U') and o.id = object_id(N'tempdb..#tmp1'))
DROP TABLE #tmp1
CREATE TABLE #tmp1 (ID INT, Data VARCHAR(20))
EXEC SP1
SELECT * FROM #tmp1
*/
My work around for this problem has always been to use the principle that single hash temp tables are in scope to any called procs. So, I have an option switch in the proc parameters (default set to off). If this is switched on, the called proc will insert the results into the temp table created in the calling proc. I think in the past I have taken it a step further and put some code in the called proc to check if the single hash table exists in scope, if it does then insert the code, otherwise return the result set. Seems to work well - best way of passing large data sets between procs.
This trick works for me.
You don't have this problem on remote server, because on remote server, the last insert command waits for the result of previous command to execute. It's not the case on same server.
Profit that situation for a workaround.
If you have the right permission to create a Linked Server, do it.
Create the same server as linked server.
in SSMS, log into your server
go to "Server Object
Right Click on "Linked Servers", then "New Linked Server"
on the dialog, give any name of your linked server : eg: THISSERVER
server type is "Other data source"
Provider : Microsoft OLE DB Provider for SQL server
Data source: your IP, it can be also just a dot (.), because it's localhost
Go to the tab "Security" and choose the 3rd one "Be made using the login's current security context"
You can edit the server options (3rd tab) if you want
Press OK, your linked server is created
now your Sql command in the SP1 is
insert into #myTempTable
exec THISSERVER.MY_DATABASE_NAME.MY_SCHEMA.SP2
Believe me, it works even you have dynamic insert in SP2
I found a work around is to convert one of the prods into a table valued function. I realize that is not always possible, and introduces its own limitations. However, I have been able to always find at least one of the procedures a good candidate for this. I like this solution, because it doesn't introduce any "hacks" to the solution.
I encountered this issue when trying to import the results of a Stored Proc into a temp table, and that Stored Proc inserted into a temp table as part of its own operation. The issue being that SQL Server does not allow the same process to write to two different temp tables at the same time.
The accepted OPENROWSET answer works fine, but I needed to avoid using any Dynamic SQL or an external OLE provider in my process, so I went a different route.
One easy workaround I found was to change the temporary table in my stored procedure to a table variable. It works exactly the same as it did with a temp table, but no longer conflicts with my other temp table insert.
Just to head off the comment I know that a few of you are about to write, warning me off Table Variables as performance killers... All I can say to you is that in 2020 it pays dividends not to be afraid of Table Variables. If this was 2008 and my Database was hosted on a server with 16GB RAM and running off 5400RPM HDDs, I might agree with you. But it's 2020 and I have an SSD array as my primary storage and hundreds of gigs of RAM. I could load my entire company's database to a table variable and still have plenty of RAM to spare.
Table Variables are back on the menu!
I recommend to read this entire article. Below is the most relevant section of that article that addresses your question:
Rollback and Error Handling is Difficult
In my articles on Error and Transaction Handling in SQL Server, I suggest that you should always have an error handler like
BEGIN CATCH
IF ##trancount > 0 ROLLBACK TRANSACTION
EXEC error_handler_sp
RETURN 55555
END CATCH
The idea is that even if you do not start a transaction in the procedure, you should always include a ROLLBACK, because if you were not able to fulfil your contract, the transaction is not valid.
Unfortunately, this does not work well with INSERT-EXEC. If the called procedure executes a ROLLBACK statement, this happens:
Msg 3915, Level 16, State 0, Procedure SalesByStore, Line 9 Cannot use the ROLLBACK statement within an INSERT-EXEC statement.
The execution of the stored procedure is aborted. If there is no CATCH handler anywhere, the entire batch is aborted, and the transaction is rolled back. If the INSERT-EXEC is inside TRY-CATCH, that CATCH handler will fire, but the transaction is doomed, that is, you must roll it back. The net effect is that the rollback is achieved as requested, but the original error message that triggered the rollback is lost. That may seem like a small thing, but it makes troubleshooting much more difficult, because when you see this error, all you know is that something went wrong, but you don't know what.
I had the same issue and concern over duplicate code in two or more sprocs. I ended up adding an additional attribute for "mode". This allowed common code to exist inside one sproc and the mode directed flow and result set of the sproc.
what about just store the output to the static table ? Like
-- SubProcedure: subProcedureName
---------------------------------
-- Save the value
DELETE lastValue_subProcedureName
INSERT INTO lastValue_subProcedureName (Value)
SELECT #Value
-- Return the value
SELECT #Value
-- Procedure
--------------------------------------------
-- get last value of subProcedureName
SELECT Value FROM lastValue_subProcedureName
its not ideal, but its so simple and you don't need to rewrite everything.
UPDATE:
the previous solution does not work well with parallel queries (async and multiuser accessing) therefore now Iam using temp tables
-- A local temporary table created in a stored procedure is dropped automatically when the stored procedure is finished.
-- The table can be referenced by any nested stored procedures executed by the stored procedure that created the table.
-- The table cannot be referenced by the process that called the stored procedure that created the table.
IF OBJECT_ID('tempdb..#lastValue_spGetData') IS NULL
CREATE TABLE #lastValue_spGetData (Value INT)
-- trigger stored procedure with special silent parameter
EXEC dbo.spGetData 1 --silent mode parameter
nested spGetData stored procedure content
-- Save the output if temporary table exists.
IF OBJECT_ID('tempdb..#lastValue_spGetData') IS NOT NULL
BEGIN
DELETE #lastValue_spGetData
INSERT INTO #lastValue_spGetData(Value)
SELECT Col1 FROM dbo.Table1
END
-- stored procedure return
IF #silentMode = 0
SELECT Col1 FROM dbo.Table1
Declare an output cursor variable to the inner sp :
#c CURSOR VARYING OUTPUT
Then declare a cursor c to the select you want to return.
Then open the cursor.
Then set the reference:
DECLARE c CURSOR LOCAL FAST_FORWARD READ_ONLY FOR
SELECT ...
OPEN c
SET #c = c
DO NOT close or reallocate.
Now call the inner sp from the outer one supplying a cursor parameter like:
exec sp_abc a,b,c,, #cOUT OUTPUT
Once the inner sp executes, your #cOUT is ready to fetch. Loop and then close and deallocate.
If you are able to use other associated technologies such as C#, I suggest using the built in SQL command with Transaction parameter.
var sqlCommand = new SqlCommand(commandText, null, transaction);
I've created a simple Console App that demonstrates this ability which can be found here:
https://github.com/hecked12/SQL-Transaction-Using-C-Sharp
In short, C# allows you to overcome this limitation where you can inspect the output of each stored procedure and use that output however you like, for example you can feed it to another stored procedure. If the output is ok, you can commit the transaction, otherwise, you can revert the changes using rollback.
On SQL Server 2008 R2, I had a mismatch in table columns that caused the Rollback error. It went away when I fixed my sqlcmd table variable populated by the insert-exec statement to match that returned by the stored proc. It was missing org_code. In a windows cmd file, it loads result of stored procedure and selects it.
set SQLTXT= declare #resets as table (org_id nvarchar(9), org_code char(4), ^
tin(char9), old_strt_dt char(10), strt_dt char(10)); ^
insert #resets exec rsp_reset; ^
select * from #resets;
sqlcmd -U user -P pass -d database -S server -Q "%SQLTXT%" -o "OrgReport.txt"
I have a stored procedure that I'm positive of has no errors but I recently deleted the table it references but imported a backup with the same name exactly and same column settings (including identity) that the previous one had but now it doesn't work.
Is there any reason that having deleted the table but importing a new would break the stored procedure?
BTW: Running Microsoft SQL Server Express Edition w/ IIS.
you can try to recompile the stored procedure with:
exec sp_recompile YourProblemTableNameHere
this will recompile all procedures that use the YourProblemTableNameHere table. But that is just a guess based on the very limited info given.
What is a "stored procedure" and how do they work?
What is the make-up of a stored procedure (things each must have to be a stored procedure)?
Stored procedures are a batch of SQL statements that can be executed in a couple of ways. Most major DBMs support stored procedures; however, not all do. You will need to verify with your particular DBMS help documentation for specifics. As I am most familiar with SQL Server I will use that as my samples.
To create a stored procedure the syntax is fairly simple:
CREATE PROCEDURE <owner>.<procedure name>
<Param> <datatype>
AS
<Body>
So for example:
CREATE PROCEDURE Users_GetUserInfo
#login nvarchar(30)=null
AS
SELECT * from [Users]
WHERE ISNULL(#login,login)=login
A benefit of stored procedures is that you can centralize data access logic into a single place that is then easy for DBA's to optimize. Stored procedures also have a security benefit in that you can grant execute rights to a stored procedure but the user will not need to have read/write permissions on the underlying tables. This is a good first step against SQL injection.
Stored procedures do come with downsides, basically the maintenance associated with your basic CRUD operation. Let's say for each table you have an Insert, Update, Delete and at least one select based on the primary key, that means each table will have 4 procedures. Now take a decent size database of 400 tables, and you have 1600 procedures! And that's assuming you don't have duplicates which you probably will.
This is where using an ORM or some other method to auto generate your basic CRUD operations has a ton of merit.
A stored procedure is a set of precompiled SQL statements that are used to perform a special task.
Example: If I have an Employee table
Employee ID Name Age Mobile
---------------------------------------
001 Sidheswar 25 9938885469
002 Pritish 32 9178542436
First I am retrieving the Employee table:
Create Procedure Employee details
As
Begin
Select * from Employee
End
To run the procedure on SQL Server:
Execute Employee details
--- (Employee details is a user defined name, give a name as you want)
Then second, I am inserting the value into the Employee Table
Create Procedure employee_insert
(#EmployeeID int, #Name Varchar(30), #Age int, #Mobile int)
As
Begin
Insert Into Employee
Values (#EmployeeID, #Name, #Age, #Mobile)
End
To run the parametrized procedure on SQL Server:
Execute employee_insert 003,’xyz’,27,1234567890
--(Parameter size must be same as declared column size)
Example: #Name Varchar(30)
In the Employee table the Name column's size must be varchar(30).
A stored procedure is a group of SQL statements that has been created and stored in the database. A stored procedure will accept input parameters so that a single procedure can be used over the network by several clients using different input data. A stored procedures will reduce network traffic and increase the performance. If we modify a stored procedure all the clients will get the updated stored procedure.
Sample of creating a stored procedure
CREATE PROCEDURE test_display
AS
SELECT FirstName, LastName
FROM tb_test;
EXEC test_display;
Advantages of using stored procedures
A stored procedure allows modular programming.
You can create the procedure once, store it in the database, and call it any number of times in your program.
A stored procedure allows faster execution.
If the operation requires a large amount of SQL code that is performed repetitively, stored procedures can be faster. They are parsed and optimized when they are first executed, and a compiled version of the stored procedure remains in a memory cache for later use. This means the stored procedure does not need to be reparsed and reoptimized with each use, resulting in much faster execution times.
A stored procedure can reduce network traffic.
An operation requiring hundreds of lines of Transact-SQL code can be performed through a single statement that executes the code in a procedure, rather than by sending hundreds of lines of code over the network.
Stored procedures provide better security to your data
Users can be granted permission to execute a stored procedure even if they do not have permission to execute the procedure's statements directly.
In SQL Server we have different types of stored procedures:
System stored procedures
User-defined stored procedures
Extended stored Procedures
System-stored procedures are stored in the master database and these start with a sp_ prefix. These procedures can be used to perform a variety of tasks to support SQL Server functions for external application calls in the system tables
Example: sp_helptext [StoredProcedure_Name]
User-defined stored procedures are usually stored in a user database and are typically designed to complete the tasks in the user database. While coding these procedures don’t use the sp_ prefix because if we use the sp_ prefix first, it will check the master database, and then it comes to user defined database.
Extended stored procedures are the procedures that call functions from DLL files. Nowadays, extended stored procedures are deprecated for the reason it would be better to avoid using extended stored procedures.
Generally, a stored procedure is a "SQL Function." They have:
-- a name
CREATE PROCEDURE spGetPerson
-- parameters
CREATE PROCEDURE spGetPerson(#PersonID int)
-- a body
CREATE PROCEDURE spGetPerson(#PersonID int)
AS
SELECT FirstName, LastName ....
FROM People
WHERE PersonID = #PersonID
This is a T-SQL focused example. Stored procedures can execute most SQL statements, return scalar and table-based values, and are considered to be more secure because they prevent SQL injection attacks.
Think of a situation like this,
You have a database with data.
There are a number of different applications needed to access that central database, and in the future some new applications too.
If you are going to insert the inline database queries to access the central database, inside each application's code individually, then probably you have to duplicate the same query again and again inside different applications' code.
In that kind of a situation, you can use stored procedures (SPs). With stored procedures, you are writing number of common queries (procedures) and store them with the central database.
Now the duplication of work will never happen as before and the data access and the maintenance will be done centrally.
NOTE:
In the above situation, you may wonder "Why cannot we introduce a central data access server to interact with all the applications? Yes. That will be a possible alternative. But,
The main advantage with SPs over that approach is, unlike your data-access-code with inline queries, SPs are pre-compiled statements, so they will execute faster. And communication costs (over networks) will be at a minimum.
Opposite to that, SPs will add some more load to the database server. If that would be a concern according to the situation, a centralized data access server with inline queries will be a better choice.
A stored procedure is mainly used to perform certain tasks on a database. For example
Get database result sets from some business logic on data.
Execute multiple database operations in a single call.
Used to migrate data from one table to another table.
Can be called for other programming languages, like Java.
A stored procedure is nothing but a group of SQL statements compiled into a single execution plan.
Create once time and call it n number of times
It reduces the network traffic
Example: creating a stored procedure
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE PROCEDURE GetEmployee
#EmployeeID int = 0
AS
BEGIN
SET NOCOUNT ON;
SELECT FirstName, LastName, BirthDate, City, Country
FROM Employees
WHERE EmployeeID = #EmployeeID
END
GO
Alter or modify a stored procedure:
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER PROCEDURE GetEmployee
#EmployeeID int = 0
AS
BEGIN
SET NOCOUNT ON;
SELECT FirstName, LastName, BirthDate, City, Country
FROM Employees
WHERE EmployeeID = #EmployeeID
END
GO
Drop or delete a stored procedure:
DROP PROCEDURE GetEmployee
A stored procedure is used to retrieve data, modify data, and delete data in database table. You don't need to write a whole SQL command each time you want to insert, update or delete data in an SQL database.
A stored procedure is a precompiled set of one or more SQL statements which perform some specific task.
A stored procedure should be executed stand alone using EXEC
A stored procedure can return multiple parameters
A stored procedure can be used to implement transact
"What is a stored procedure" is already answered in other posts here. What I will post is one less known way of using stored procedure. It is grouping stored procedures or numbering stored procedures.
Syntax Reference
; number as per this
An optional integer that is used to group procedures of the same name. These grouped procedures can be dropped together by using one DROP PROCEDURE statement
Example
CREATE Procedure FirstTest
(
#InputA INT
)
AS
BEGIN
SELECT 'A' + CONVERT(VARCHAR(10),#InputA)
END
GO
CREATE Procedure FirstTest;2
(
#InputA INT,
#InputB INT
)
AS
BEGIN
SELECT 'A' + CONVERT(VARCHAR(10),#InputA)+ CONVERT(VARCHAR(10),#InputB)
END
GO
Use
exec FirstTest 10
exec FirstTest;2 20,30
Result
Another Attempt
CREATE Procedure SecondTest;2
(
#InputA INT,
#InputB INT
)
AS
BEGIN
SELECT 'A' + CONVERT(VARCHAR(10),#InputA)+ CONVERT(VARCHAR(10),#InputB)
END
GO
Result
Msg 2730, Level 11, State 1, Procedure SecondTest, Line 1 [Batch Start Line 3]
Cannot create procedure 'SecondTest' with a group number of 2 because a procedure with the same name and a group number of 1 does not currently exist in the database.
Must execute CREATE PROCEDURE 'SecondTest';1 first.
References:
CREATE PROCEDURE with the syntax for number
Numbered Stored Procedures in SQL Server - techie-friendly.blogspot.com
Grouping Stored Procedures - sqlmag
CAUTION
After you group the procedures, you can't drop them individually.
This feature may be removed in a future version of Microsoft SQL Server.
for simple,
Stored Procedure are Stored Programs, A program/function stored into database.
Each stored program contains a body that consists of an SQL statement. This statement may be a compound statement made up of several statements separated by semicolon (;) characters.
CREATE PROCEDURE dorepeat(p1 INT)
BEGIN
SET #x = 0;
REPEAT SET #x = #x + 1; UNTIL #x > p1 END REPEAT;
END;
A stored procedure is a named collection of SQL statements and procedural logic i.e, compiled, verified and stored in the server database. A stored procedure is typically treated like other database objects and controlled through server security mechanism.
In a DBMS, a stored procedure is a set of SQL statements with an assigned name that's stored in the database in compiled form so that it can be shared by a number of programs.
The use of a stored procedure can be helpful in
Providing a controlled access to data (end users can only enter or change data, but can't write procedures)
Ensuring data integrity (data would be entered in a consistent manner) and
Improves productivity (the statements of a stored procedure need to be written only once)
Stored procedures in SQL Server can accept input parameters and return multiple values of output parameters; in SQL Server, stored procedures program statements to perform operations in the database and return a status value to a calling procedure or batch.
The benefits of using stored procedures in SQL Server
They allow modular programming.
They allow faster execution.
They can reduce network traffic.
They can be used as a security mechanism.
Here is an example of a stored procedure that takes a parameter, executes a query and return a result. Specifically, the stored procedure accepts the BusinessEntityID as a parameter and uses this to match the primary key of the HumanResources.Employee table to return the requested employee.
> create procedure HumanResources.uspFindEmployee `*<<<---Store procedure name`*
#businessEntityID `<<<----parameter`
as
begin
SET NOCOUNT ON;
Select businessEntityId, <<<----select statement to return one employee row
NationalIdNumber,
LoginID,
JobTitle,
HireData,
From HumanResources.Employee
where businessEntityId =#businessEntityId <<<---parameter used as criteria
end
I learned this from essential.com...it is very useful.
Stored Procedure will help you to make code in server.You can pass parameters and find output.
create procedure_name (para1 int,para2 decimal)
as
select * from TableName
In Stored Procedures statements are written only once and reduces network traffic between clients and servers.
We can also avoid Sql Injection Attacks.
Incase if you are using a third party program in your application for
processing payments, here database should only expose the
information it needed and activity that this third party has been
authorized, by this we can achieve data confidentiality by setting
permissions using Stored Procedures.
The updation of table should only done to the table it is targeting
but it shouldn't update any other table, by which we can achieve
data integrity using transaction processing and error handling.
If you want to return one or more items with a data type then it is
better to use an output parameter.
In Stored Procedures, we use an output parameter for anything that
needs to be returned. If you want to return only one item with only
an integer data type then better use a return value. Actually the
return value is only to inform success or failure of the Stored
Procedure.
Preface: In 1992 the SQL92 standard was created and was popularised by the Firebase DB. This standard introduced the 'Stored Procedure'.
**
Passthrough Query: A string (normally concatenated programatically) that evaluates to a syntactically correct SQL statement, normally generated at the server tier (in languages such as PHP, Python, PERL etc). These statements are then passed onto the database.
**
**
Trigger: a piece of code designed to fire in response to a database event (typically a DML event) often used for enforcing data integrity.
**
The best way to explain what a stored procedure is, is to explain the legacy way of executing DB logic (ie not using a Stored Procedure).
The legacy way of creating systems was to use a 'Passthrough Query' and possibly have triggers in the DB.
Pretty much anyone who doesn't use Stored Procedures uses a thing call a 'Passthrough Query'
With the modern convention of Stored Procedures, triggers became legacy along with 'Passthrough Queries'.
The advantages of stored procedures are:
They can be cached as the physical text of the Stored Procedure
never changes.
They have built in mechanisms against malicious SQL
injection.
Only the parameters need be checked for malicious SQL
injection saving a lot of processor overhead.
Most modern database
engines actually compile Stored Procedures.
They increase the
degree of abstraction between tiers.
They occur in the same
process as the database allowing for greater optimisation and
throughput.
The entire workflow of the back end can be tested
without client side code. (for example the Execute command in
Transact SQL or the CALL command in MySQL).
They can be used to
enhance security because they can be leveraged to disallow the
database to be accessed in a way that is inconsistent with how the
system is designed to work. This is done through the database user
permission mechanism. For example you can give users privileges only
to EXECUTE Stored Procedures rather that SELECT, UPDATE etc
privileges.
No need for the DML layer associated with triggers. **
Using so much as one trigger, opens up a DML layer which is very
processor intensive **
In summary when creating a new SQL database system there is no good excuse to use Passthrough Queries.
It is also noteworthy to mention that it is perfectly safe to use Stored Procedures in legacy systems that already uses triggers or Passthrough Queries; meaning that migration from legacy to Stored Procedures is very easy and such migration need not take a system down for long if at all.
create procedure <owner>.<procedure name><param> <datatype>
As
<body>
Stored procedure are groups of SQL statements that centralize data access in one point. Useful for performing multiple operations in one shot.