ims 4212: application architecture and intro to stored procedures 1 dr. lawrence west, management...

IMS 4212: Application Architecture and Intro to Stored Procedures

1Dr. Lawrence West, Management Dept., University of Central [email protected]

Stored Procedures in SQL Server

• Architecture Overview

• Designing and Creating SP

• SP Variables and Return Values

• Odds ‘n’ Ends



Architecture Elements

• A full-fledged systems production and operation environment will consist of a multitude of elements

– Databases

• Tables, relationships, indices

• Stored procedures

– Database connectivity

• System connectivity (DSN, ODBC, ADO.Net)

• Application connectivity

– Applications



Architecture Elements (cont.)

• Next few weeks will be dealing with these elements

• It will be important that you understand individual topics in the context of this framework

DATABASE COMPONENTS

TABLES &RELATIONSHIPS

STOREDPROCEDURES

APPLICATIONSDATABASECONNECTIVITY

(ODBC/ADO)



Stored Procedures

• Stored Procedures (SP) are procedural instructions stored within the database

• SP can be called by other SP or by external applications

• Simplest SP execute a single SQL statement

• SP can be incredibly complex

• SP can accept variable values

• SP can return results

– Individual discrete values

– Entire recordsets (query results)

– Output parameters (multiple discrete values)



Script to Create a Simple Stored Procedure

CREATE PROCEDURE up_Organization_Update @OrgID bigint,@OrgName varchar(50),@AcctName varchar(50),@WireAcct varchar(25)AS UPDATE Organization SET OrgName = @OrgName, AcctName = @AcctName, WireAcct = @WireAcct WHERE OrgID = @OrgIDGO

More on this SPlater



SP Advantages

• Centralized

– Any application can access the SP because it is stored with the database

– Maintenance takes place in one location

• Fast!!

– DB compiles SP and develops an ‘execution plan’ the first time the SP is run

– Subsequent runs are as fast as they can be

• Secure

– SP logic is hidden from anyone who does not have permissions to view the object

Really Important



Designing SP

• Most tables will need INSERT INTO and UPDATE SP

• Identify other SP needed for your application’s business logic

– DELETE

– Specialized SELECT queries

• Retrieve an individual record by some criteria

• Retrieve a collection of records by a criteria

• Retrieve all records in a table

• All business logic data access will take place in SP

• SP can contain any data manipulation queries



Designing SP (cont.)

• Naming Stored Procedures

– All begin with “up” for User Procedure

– Rest of name should give purpose of query

– Single table procedures should be “up_tablename_purpose”

– Examples

• up_customers_insert

• up_customers_selectbyCustID

• up_monthlysalesdetail_bymonth

SP appear alphabetically

in Enterprise M

anager



Creating SP

• SP are created in Enterprise Manager

• Executing the CREATE PROCEDURE command creates the SP as an object in the DB

• SP can be modified in the Enterprise Manager using ALTER PROCEDURE

• Be sure to save your SP files from Query Analyzer so they can be modified and rerun if necessary

Demonstration



Creating SP (cont.)

• CREATE PROCEDURE procedure_name[parameter list]AS

– Creates procedure

– Parameter names must start with ‘@’

– Parameters are typed with SQL Server data types

– Parameters should match field typesCREATE PROCEDURE up_Organization_Update @OrgID bigint,@OrgName varchar(50),@AcctName varchar(50),@WireAcct varchar(25)AS



Creating SP (cont.)

• Body of procedureexecutes logic

• Parameters are usedlike variables in theSQL statements

• Note that there are no delimiters (single quotes for text or #-signs for dates) around these values

UPDATE Organization SET OrgName = @OrgName, AcctName = @AcctName, WireAcct = @WireAcct WHERE OrgID = @OrgIDGO



SP Variables and Return Values

• When SP create a recordset with an SQL SELECT statement that recordset is available to the calling procedure or application (more later)

• SP may return a value with the RETURN(@varname) syntax

• If @varname is not an input parameter it must be created with the DECLARE statementDECLARE @varname datatype

• Use SET to assign a value to a variable

• @@ERROR and @@IDENTITY are common intrinsic values that are returned



SP Variables & Return Values (cont.)

CREATE PROCEDURE up_Shippers_Insert @CompanyName nvarchar(40),@Phone nvarchar(24)ASDECLARE @ShipperID int

--Perform the insertINSERT INTO Shippers ( CompanyName, Phone) VALUES (@CompanyName, @Phone)

--Load the PK into the return parameterSET @ShipperID = @@IdentityRETURN (@ShipperID)

GO

Parameters

Declare internal variable

@@Identity gives identityattribute value of most recently added record

Returning the variable value



SP Variables & Return Values (cont.)

• Notes:– RETURN can only return a variable in SQL Server

2000 and earlier• RETURN(@@Identity) works SQL 2005 & later

– Pay careful attention to data types• When a parameter variable or internal variable

interacts directly with a table field the field and the variable must be of a compatible data type

• Ensure that varchar variables and fields are the same length

– We will see how to read returned recordset values next time



More on SP

• SP can actually be incredibly rich procedural code using T-SQL (transact SQL)

– Conditional execution

– Looping execution

– Branching execution

– Calling other SP (reusable logic modules)

• Oracle and other DB have similar capabilities

• Most common SP execute discrete DB activities based around SELECT, INSERT INTO, UPDATE, and DELETE statements



Exercises

• Create SP to:

– Return a list of CategoryID and CategoryName values sorted by name

– Receive a CategoryID and return all product details for products in that category

– Receive a country name and return all product details for products from that country

– Add a new Order Details recordHint: Be sure that you use valid OrderID and ProductID values



Alter Procedure

• You may also update a stored procedure using the ALTER PROCEDURE procedure_name syntax

– Right click procedure name in Query Analyzer Object Browser

– Select Modify from menu



Alter Procedure (cont.)

SET QUOTED_IDENTIFIER ON GOSET ANSI_NULLS ON GO

ALTER PROCEDURE up_Region_Insert@RegionID int,@RegionDescription nchar(50)AS

INSERT INTO Region (RegionID, RegionDescription)VALUES (@RegionID, @RegionDescription)

GOSET QUOTED_IDENTIFIER OFF GOSET ANSI_NULLS ON GO

Added by editor



Commenting SPs

/* up_Shippers_Add** Receives input parameters for the two non-identity attributes of* the shippers table and adds a new shippers record* Retrieves the value of the newly created record PK and* returns it as the return value of the SP*/

• Comment purpose of SP at top

• Use /*… */ to create a block comment

• -- at beginning of a line creates a comment on the line



Default Parameter Values

• A value must be provided for every parameter

– But a parameter need not be provided for every field

• A default value can be provided in the SP which will be used if the calling application does not provide one

• All of the following are legal:CREATE PROCEDURE up_ProcedureName@CompanyName nvarchar(40),@OrderDate = GetDate(),@EmployeeID = 0,@ShippedDate = NULLAS

Value must be providedWill use current date if no valWill use zero if no valueNeed not receive a value and will enter NULL if none provided



Testing SP From Query Analyzer

DELETE Shippers WHERE CompanyName = 'Test Co'

--Testing by adding values in list in parameter orderEXEC up_Shippers_Add 'Test Co', '555-1212'GO

--Testing by providing named parameter valuesEXEC up_Shippers_Add @CompanyName = 'Test Co', @Phone = 'Explicit'GO

--Testing by adding named parameter values reversedEXEC up_Shippers_Add @Phone = 'Reverse', @CompanyName = 'Test Co'

--Testing by providing no phone number with default providedEXEC up_Shippers_Add 'Test Co'

SELECT * FROM Shippers



What’s To Come

• The Stored Procedures we will build here can easily be invoked from our Visual Basic programs

• Syntax is a little complex but is always the same for the same kind of SP

• Learn VB syntax (mimic the example code) and the applications are straightforward to implement

ims 4212: application architecture and intro to stored procedures 1 dr. lawrence west, management...

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