Matakuliah : M0492 / Web-based Programming Lanjut
Tahun
: 2007
Web-based Programming Lanjut
Pertemuan 7
Connection, Command dan Procedure
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The Connection Object
The Command Object
Stored Procedure
Optimization
Data Shaping
The Connection Object
• Connection object
– Gives us connection to the data store
– Run the commands
• action queries (updates, inserts, deletes)
• return a recordset
• Returning a Recordset
To return a recordset use the ‘Execute’ method
The syntax is:
Connection.Execute CommandText, [RecordsAffected], [Options]
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The Connection Object
Argument
Description
CommandText
The text of the command to execute. This is the same as the ‘Source’ of the Recordset ‘Open’ method, and can
also represent an existing Command object.
RecordsAffected
A variable into which is placed the number of records affected by the command.
Options
The command options, which can be one or more of the values from the CommandTypeEnum or
ExecuteOptionEnum constants, as detailed in session 6.
Set conPubs = Server.CreateObject(“ADODB.Connection”)
conPubs.Open strConn
Set rsAuthors = conPubs.Execute (“Authors”)
The difference between Execute and Open method:
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Open method have the ability to change the cursor type and lock type
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Execute method always get a forward-only cursor and read-only recordset.
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The Connection Object
• Action Commands
You can use the RecordsAffected argument to find out how many records were
affected by the command.
Dim strSQL as String
Dim lngRecs as Long
strSQL = “UPDATE Titles SET Price = Price * 1.10 WHERE Type=‘Business’”
conPubs.Execute strSQL, lngRecs, adCmdText
Response.Write lngRecs & “ records were updated.”
• No Recordset Returned
If no recordset is being returned, then it’s also best to add another option to the
Execute statement :
conPubs.Execute strSQL, lngRecs, adCmdText + adExecuteNoRecords
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The Command Object
• Command Object
– Deal with commands of any sort, especially that require parameters.
– Can run both commands that return recordsets and not return recordsets.
– If your command doesn’t have parameters, then it doesn’t matter whether you
use a Connection, a Command, or a Recordset.
• Returning Recordsets
– use the Execute method and the CommandText property.
Set cmdAuthors = Server.CreateObject(“ADODB.Command”)
cmdAuthors.CommandText = “Authors”
Set rsAuthors = cmdAuthors.Execute
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The Command Object
The Execute method also has some optional arguments:
Argument
Description
RecordsAffected
A variable into which is placed the number of records affected by the command.
Parameters
An array of parameter values.
Options
The command options. This is similar to the ‘Options’ of the Recordset ‘Open’ method.
Set cmdAuthors = Server.CreateObject(“ADODB.Command”)
cmdAuthors.CommandText = “Authors”
cmdAuthors.CommandType = adCmdTable
Set rsAuthors = cmdAuthors.Execute
Or
Set rsAuthors = cmdAuthors.Execute (, , adCmdTable)
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The Command Object
• Changing the Cursor Type
If require a different cursor or lock type, use the Open method.
cmdAuthors.ActiveConnection = strConn
cmdAuthors.CommandText = “Authors”
cmdAuthors.CommandType = adCmdTable
rsAuthors.Open cmdAuthors, , adOpenDynamic, adLockOptimistic
• Action Command
For action commands, such as update data without returning any records:
Set cmdUpdate = Server.CreateObject(“ADODB.Command”)
StrSQL = “UPDATE Titles SET Price = Proce * 1.10 WHERE Type = ‘Business’”
cmdUpdate.ActiveConnection = strConn
cmdUpdate.CommandText = strSQL
cmdUpdate.CommandType = adCmdText
cmdUpdate.Execute , , adExecuteNoRecords
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Stored Procedures
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A stored procedures (stored query) is a predefined SQL query stored on the database.
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The reasons why we create and use a stored procedure:
– Compiled by database. Produces an execution plan, so the database knows exactly what it’s
going to do. This makes the execution of the procedure faster.
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Stored procedures are often cached by the database, thus making them faster to run. Not all
databases support this caching mechanism – Microsoft Access doesn’t, but SQL Server does.
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More secure by specifying that your database tables can be modified only by stored
procedures.
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Avoid cluttering ASP code with lengthy SQL statements. This makes the ASP code easier to
maintain.
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Keep all the SQL code together, on the server.
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Can use output parameters, which allows to return both a recordset and other values.
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Stored Procedures
A stored procedure on SQL Server
CREATE PROCEDURE usp_UpdatePrices
AS
UPDATE Titles
SET Price = Price * 1.10
WHERE Type = ‘Business’
For a Microsoft Access database,
you can create a simple update
query to do the same task
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Stored Procedures
• To run this stored procedure from an ASP page, you’d simply use the following
code:
Set cmdUpdate = Server.CreateObject (“ADODB.COmmand”)
cmdUpdate.ActiveConnection = strConn
cmdUpdate.CommandText = “usp_UpdatePrices”
cmdUpdate.CommandType = adCmdStoredProc
cmdUpdate.Execute , , adExecuteNoRecords
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Stored Procedures
• Parameters
Must follow the naming convention for SQL variables, which means they must
start with an @ symbol.
CREATE PROCEDURE usp_UpdatePrices
@Type
Char(12),
@Percent
Money
AS
UPDATE Titles
SET Price = Price * ( 1 + @Percent / 100 )
WHERE Type = @Type
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Stored Procedures
• The Parameters Collection
Set Parameter = Command.CreateParameter (Name, [Type], [Direction], [Size],
[Value])
Argument
Description
Name
The name of the parameter. This isn’t the name of the parameter in the stored procedure, but the name of the parameter in the
Parameters collection. It is however, a good idea to use the same names.
Type
The data type of the parameter. This can be one of the adDataType constants, which are detailed in the appendices.
Direction
The direction of the parameter, indicating whether the parameter supplies information to the stored procedure, or whether the
procedure supplies the information back to ADO. The value can be one of:
• adParamInput (1), is an input parameter, being sent to the stored procedure.
• adParamOutput (2), is an output parameter, being retrieved from the stored procedure.
• adParamInputOutput (3), is both an input and an output parameter.
• adParamReturnValue (4), holds the return status of the stored procedure.
Size
The size of the parameter. For fixed length types, such as numbers, this can be omitted.
Value
The value of the parameter.
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Stored Procedures
• Once the parameter is created it can be appended to the Parameters collection.
Set parValue = cmdUpdate.CreateParameter (“@Type”, adVarWChar, adParamInput, 12, “Business”)
cmdUpdate.Parameters.Append parValue
Set parValue = cmdUpdate.CreateParameter (“@Percent”, adCurrency, adParamInput, ,10)
cmdUpdate.Parameters.Append parValue
cmdUpdate.Parameters(“@Percent”) = 10
If you don’t want to create a variable, you can also take a shortcut :
cmdUpdate.Parameters.Append = _
cmdUpdate.CreateParameter (“@Type”, adVarWChar, adParamInput, 12, “Business”)
cmdUpdate.Parameters.Append = _
cmdUpdate.CreateParameter (“@Percent”, adCurrency, adParamInput, ,10)
cmdUpdate.Parameters(“@Percent”) = 10
The Parameters in the Parameters collection must match the order of the
parameters in the stored procedure.
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Stored Procedures
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<HTML><HEAD><TITLE>Stored Procedure with Parameter</TITLE></HEAD><!-- UpdatePrices.asp -->
<BODY>
<!-- #include file="dataconn.inc" -->
<FORM NAME="UpdatePrices" Method="Post" ACTION="StoredProcedure.asp">
<TABLE>
<TR><TD>Book Type:</TD>
<TD><SELECT NAME="lstTypes">
<%
Dim rsTypes
Dim strSQL
Dim strQuote
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strQuote = Chr(34)
'Predefined the quote character
Set rsTypes = Server.CreateObject("ADODB.Recordset")
strSQL = "SELECT DISTINCT type FROM titles"
rsTypes.Open strSQL, Conn
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While Not rsTypes.EOF
Response.Write "<OPTION VALUE=" & strQuote & rsTypes("Type") & strQuote & ">" & rsTypes("Type")
rsTypes.MoveNext
Wend
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rsTypes.Close
Set rsTypes = Nothing
%></SELECT></TD></TR>
<TR><TD>Percent Value</TD>
<TD><INPUT NAME="txtPercent" TYPE="TEXT"></TD></TR>
</TABLE>
<P><INPUT TYPE="Submit" VALUE="Run Query">
</FORM></BODY></HTML>
Stored Procedures
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<!-- #include file="dataconn.inc" -->
<!-- StoredProcedure.asp -->
<%
Dim cmdUpdate
Dim lngRecs
Dim strType
Dim curPercent
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'get from the values
strType = Request.Form("lstTypes")
curPercent = Request.Form("txtPercent")
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'Tell the user what's being done
Response.Write "Updating all books of type <B>" & strType & "</B> by " & curPercent & "%<P>"
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Set cmdUpdate = Server.CreateObject("ADODB.Command")
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' Set the properties of the command
With cmdUpdate
.ActiveConnection = conn
.CommandText = "usp_UpdatePrices"
.CommandType = 4
‘adCmdStoredProc = 4
.Parameters.Append .CreateParameter("@Type", 202, 1, 12, strType) ‘adVarWChar = 202, adParamInput=1
.Parameters.Append .CreateParameter("@Percent", 6, 1,, curPercent) ‘adCurrency = 6
.Execute lngRecs,,128
‘adExecuteNoRecords=128
End With
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'And finally tell the user what's happened
Response.Write "Procedure complete. " & lngRecs & " records were updated."
Set cmdUpdate = Nothing
%>
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Stored Procedures
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Stored Procedures
• Passing Parameters as an Array
Utilizes the Array function, which turns individual variables into an array, suitable
for passing into this method call.
Some disadvantages to this method:
– You can only use input parameters.
– This method is slower if you intend to call the stored procedure several times,
since ADO will ask the data store what parameters are, and what data types
they use.
Set cmdUpdate = Server.CreateObject(“ADODB.Command”)
With cmdUpdate
.ActiveConnection = conn
.CommandText = “usp_UpdatePrices”
.CommandType = adCmdStoredProc
‘Execute the command
.Execute lngRecs, Array(strType, curPercent), adExecuteNoRecords
End With
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Stored Procedures
• Output Parameters
If you want more information, but still don’t want to return a recordset, you can
define a parameter as an output parameter.
CREATE PROCEDURE usp_UpdatePricesMax
@Type
Char(12),
@Percent Money,
@Max
Money OUTPUT
AS
UPDATE Titles
SET Price = Price * ( 1 + @Percent / 100 )
WHERE Type = @Type
SELECT @Max = MAX(Price)
FROM Titles
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Stored Procedures
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<!-- #include file="dataconn.inc" --> <!-- StoredProcedureMax.asp -->
<%
Dim cmdUpdate
Dim lngRecs
Dim strType
Dim curPercent
Dim curMax
'get from the values
strType = Request.Form("lstTypes")
curPercent = Request.Form("txtPercent")
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'Tell the user what's being done
Response.Write "Updating all books of type <B>" & strType & "</B> by " & curPercent & "%<P>"
Set cmdUpdate = Server.CreateObject("ADODB.Command")
' Set the properties of the command
With cmdUpdate
.ActiveConnection = conn
.CommandText = "usp_UpdatePricesMax"
.CommandType = 4
‘adCmdStoredProc = 4
.Parameters.Append .CreateParameter("@Type", 202, 1, 12, strType) ‘adVarWChar = 202, adParamInput=1
.Parameters.Append .CreateParameter("@Percent", 6, 1,, curPercent) ‘adCurrency = 6
.Parameters.Append .CreateParameter("@Max", 6, 2)
‘adCurrency = 6, adParamOutput=2
.Execute lngRecs,,128
‘adExecuteNoRecords=128
curmax = .Parameters(“@Max”)
‘Extract the OUTPUT parameter
End With
'And finally tell the user what's happened
Response.Write "Procedure complete. " & lngRecs & " records were updated.“
Response.Write "The highest price book is now " & FormatCurrency(curMax)
Set cmdUpdate = Nothing
%>
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Stored Procedures
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Stored Procedures
• Return Values
– Return values from functions are handled differently from the way return
values from stored procedures.
– In user functions, we often return a Boolean value to indicate the success or
failure of a function
– When calling a stored procedure though, we can’t use the same method. The
stored procedure are run using the Execute method, and this returns a
recordset.
For example, consider adding a new employee to the employee table. You don’t
want to stop two people with the same name being added, but you might want
this situation flagged. Here we can use a return value, to indicate whether an
employee wuth the same name already exists.
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Stored Procedures
CREATE PROCEDURE usp_AddEmployee
@Emp_ID
Char(9),
@FName
Varchar(20),
@MInit
Char(1),
@LName
Varchar(30),
@Job_Id
SmallInt,
@Job_Lvl
TinyInt,
@Pub_ID
Char(4),
@Hire_Date
Datetime
AS
BEGIN
DECLARE @Exists
Int
-- Return Value
-- See if an employee with the same name exists
IF EXISTS (SELECT *
FROM Employee
WHERE FName = @FName
AND MInit = @MInit
AND LName = @LName)
SELECT @Exists = 1
ELSE
SELECT @Exists = 0
INSERT INTO Employee (emp_id, fname, minit, lname, job_id, job_lvl, pub_id, hire_date)
VALUES (@Emp_ID, @FName, @MInit, @LName, @Job_Id, @Job_Lvl, @Pub_ID, @Hire_Date)
RETURN @Exists
END
GO
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Stored Procedures
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<HTML><HEAD><TITLE>Stored Procedure with Return Values</TITLE></HEAD><!-- ReturnValues.asp -->
<BODY><!-- #include file="dataconn.inc" -->
<H1>Retuen Values from stored procedures<HR></H1>
<FORM NAME="ReturnValues" Method="Post" ACTION="StoredProcedureAdd.asp">
<TABLE>
<TR><TD>Employee ID:</TD> <TD><INPUT NAME="txtEmp_ID" TYPE="TEXT"></TD></TR>
<TR><TD>First Name:</TD> <TD><INPUT NAME="txtFName" TYPE="TEXT"></TD></TR>
<TR><TD>Initial:</TD> <TD><INPUT NAME="txtMInit" TYPE="TEXT"></TD></TR>
<TR><TD>Last Name:</TD> <TD><INPUT NAME="txtLName" TYPE="TEXT"></TD></TR>
<TR><TD>Job:</TD><TD>
<SELECT NAME="lstJob">
<%
Dim rsJobs
Dim strSQL
Dim strQuote
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strQuote = Chr(34) 'Predefined the quote character
Set rsJobs = Server.CreateObject("ADODB.Recordset")
strSQL = "SELECT DISTINCT job_id, job_desc FROM jobs"
rsJobs.Open strSQL, Conn
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While Not rsJobs.EOF
Response.Write "<OPTION VALUE=" & strQuote & _
rsJobs("job_id") & strQuote & ">" & rsJobs("job_desc")
rsJobs.MoveNext
Wend
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rsJobs.Close
Set rsJobs = Nothing
%></SELECT></TD></TR>
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Stored Procedures
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<TR><TD>Job Level: </TD><TD><INPUT NAME="txtJob_Lvl" TYPE="TEXT"></TD></TR>
<TR><TD>Publisher: </TD><TD><SELECT NAME="lstPub">
<%
Dim rsPub
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Set rsPub = Server.CreateObject("ADODB.Recordset")
strSQL = "SELECT DISTINCT pub_id, pub_name FROM publishers"
rsPub.Open strSQL, Conn
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While Not rsPub.EOF
Response.Write "<OPTION VALUE=" & strQuote & _
rsPub("pub_id") & strQuote & ">" & rsPub("pub_name")
rsPub.MoveNext
Wend
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rsPub.Close
Set rsPub = Nothing
%></SELECT></TD></TR>
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<TR><TD>Hire Date: </TD>
<TD><INPUT NAME="txtHire_Date" TYPE="TEXT" Value="<%= FormatDateTime(date()) %>"></TD>
</TR>
</TABLE>
<P>
<INPUT TYPE="Submit" VALUE="Run Query">
</FORM>
</BODY>
</HTML>
Stored Procedures
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<!-- #include file="dataconn.inc" --><!-- StoredProcedureAdd.asp -->
<%
Dim cmdEmployee
Dim lngRecs
Dim lngAdded
Set cmdEmployee = Server.CreateObject("ADODB.Command")
With cmdEmployee
.ActiveConnection = conn
.CommandText = "usp_AddEmployee"
.CommandType = 4
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.Parameters.Append .CreateParameter("RETURN_VALUE", 3, 4)
.Parameters.Append .CreateParameter("@Emp_ID", 129, 1, 9)
.Parameters.Append .CreateParameter("@FName", 202, 1,20)
.Parameters.Append .CreateParameter("@MInit", 129, 1, 1)
.Parameters.Append .CreateParameter("@LName", 202, 1,30)
.Parameters.Append .CreateParameter("@Job_Id", 2, 1)
.Parameters.Append .CreateParameter("@Job_Lvl", 17, 1)
.Parameters.Append .CreateParameter("@Pub_ID", 129, 1, 4)
.Parameters.Append .CreateParameter("@Hire_Date", 135, 1,8)
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.Parameters("@Emp_ID") = Request.Form("txtEmp_ID")
.Parameters("@FName") = Request.Form("txtFName")
.Parameters("@MInit") = Request.Form("txtMInit")
.Parameters("@LName") = Request.Form("txtLName")
.Parameters("@Job_Id") = Request.Form("lstJob")
.Parameters("@Job_Lvl") = Request.Form("txtJob_Lvl")
.Parameters("@Pub_ID") = Request.Form("lstPub")
.Parameters("@Hire_Date") = Request.Form("txtHire_Date")
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.Execute lngRecs,,128
lngAdded = .Parameters("RETURN_VALUE")
%>
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End With
Response.Write "New Employee added.<P> "
If lngAdded = 1 Then
Response.Write "An Employee with the same name already exists."
End If
Set cmdEmployee = Nothing
Stored Procedures
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Stored Procedures
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Refreshing Parameters
Instead of typing in all of the parameter details yourself, ADO can do it for you, simply by
calling the Refresh method .
But be aware that it imposes a performance penalty, since ADO must query the provider
for the details of the parameters for the stored procedure.
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With cmdEmployee
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.ActiveConnection = conn
.CommandText = "usp_AddEmployee"
.CommandType = 4
.Parameters.Refresh
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.Parameters("@Emp_ID") = Request.Form("txtEmp_ID")
.Parameters("@FName") = Request.Form("txtFName")
.Parameters("@MInit") = Request.Form("txtMInit")
.Parameters("@LName") = Request.Form("txtLName")
.Parameters("@Job_Id") = Request.Form("lstJob")
.Parameters("@Job_Lvl") = Request.Form("txtJob_Lvl")
.Parameters("@Pub_ID") = Request.Form("lstPub")
.Parameters("@Hire_Date") = Request.Form("txtHire_Date")
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.Execute lngRecs,,128
lngAdded = .Parameters("RETURN_VALUE")
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End With
Optimization
• General ADO Tips
– Pick only the columns you need
– Use stored procedures as much as possible
– Use stored procedures for data changes
– Don’t create a recordset unless it’s required
– Use the appropriate cursor and lock modes
• Object Variables
– One guaranteed way to improve performance whilst looping through recordset
is to use object variables
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Optimization
• Cache Size
– Cache size is the number of records that ADO reads at a time from the data
sore, and it defaults to 1.
– The size 1 means, every time you move to another record, the record must be
fetched from the data store.
– Increasing the size of the cache to 10, for example, would mean that records
are read into the ADO buffer 10 at a time.
– Set the size of the cache by using the CacheSize property :
rsAuthors.CacheSize = 10
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Data Shaping
• Allows to represent a tree-like structure or related recordset.
• Reasons why this is useful:
– Performance : When used correctly, data shaping can improve performance
– Convenience : It’s extremely easy to map the parent/child relationship in data
shaping.
• Using data shaping
– Use the MSDataShape OLEDB Provider
– Use a special Shape language, a superset of SQL, that allows you to construct
the hierarchies
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Data Shaping
• The Connection String
Provider=MSDataShape; Data Provider = SQLOLEDB; Data
Source=…
• The Shape Language
SHAPE {parent command} [AS parent alias]
APPEND ({child command} [AS child alias]
RELATE parent_column TO child_column) [AS
parent_column_name]
For Example:
SHAPE {SELECT * FROM Publishers }
APPEND ({SELECT * FROM Titles}
RELATE Pub_ID TO Pub_ID) AS rsTitles
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Data Shaping
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<!-- #include file="dataconn.inc" --><!-- DataShape.asp -->
<%
Dim rsPublishers
Dim rsTitles
Dim strShapeConn
Dim strShape
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Set rsPublishers = Server.CreateObject("ADODB.Recordset")
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strShapeConn = "Provider = MSDataShape; Data Provider = SQLOLEDB; Data Source= Hogwartz; " & _
" Initial Catalog= pubs; User ID= sa; Password= letmein"
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strShape = "SHAPE {SELECT * FROM Publishers } APPEND ({SELECT * FROM Titles} " & _
" RELATE Pub_ID TO Pub_ID) AS rsTitles "
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rsPublishers.Open strShape, strShapeConn
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'Loop through the publishers
Response.Write "<UL>"
While Not rsPublishers.EOF
Response.Write "<LI>" & rsPublishers("Pub_Name")
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'Now the titles
Response.Write "<UL>"
Set RsTitles = rsPublishers("rsTitles").Value
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'Loop through the titles
While Not rsTitles.EOF
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'Move to the next publishers
rsPublishers.MoveNext
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%>
Response.Write "<LI>" & rsTitles("title")
rsTitles.MoveNext
Wend
Response.Write "</UL>"
Wend
Response.Write "</UL>"
rsPublishers.Close
Set rsPublishers = Nothing
Set rsTitles = Nothing
Data Shaping
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