n overloads public overridable function add(byval value as object) as integer implements ilist.add
n overloads public function add(byval parametername as string,byval value as object) as oledbparameter
n overloads public function add(byval value as oledbparameter) as oledbparameter
n overloads public function add(byval parametername as string,byval oledbtype as oledbtype) as oledbparameter
n overloads public function add(byval parametername as string,byval oledbtype as oledbtype,byval size as integer) as oledbparameter
n overloads public function add(byval parametername as string,byval oledbtype as oledbtype,byval size as integer,byval sourcecolumn as string) as oledbparameter
示例
public sub createoledbparamcoll(myconn as oledbconnection)
dim mycommand as oledbcommand = new oledbcommand("select * from customers where customerid = ?", myconn)
dim myparamcollection as oledbparametercollection = mycommand.parameters
dim myparm as object = new oledbparameter("customerid", oledbtype.varchar)
dim pindex as integer = myparamcollection.add(myparm)
dim myparm as oledbparameter = myparamcollection.add(new oledbparameter("customerid", oledbtype.varchar))
dim myparm as oledbparameter = myparamcollection.add("customerid", “customeridvalue”);
dim myparm as oledbparameter = myparamcollection.add("customerid", oledbtype.varchar)
dim myparm as oledbparameter = myparamcollection.add("customerid", oledbtype.varchar, 5)
dim myparm as oledbparameter = myparamcollection.add("customerid", oledbtype.varchar, 5, "customerid")
end sub
示例
public shared function createcustomeradapter(conn as oledbconnection) as oledbdataadapter
dim da as oledbdataadapter = new oledbdataadapter()
dim cmd as oledbcommand
dim parm as oledbparameter
' create the selectcommand.
cmd = new oledbcommand("select * from customers where country = @country and city = @city", conn)
cmd.parameters.add("@country", oledbtype.varchar, 15)
cmd.parameters.add("@city", oledbtype.varchar, 15)
da.selectcommand = cmd
' create the insertcommand.
cmd = new oledbcommand("insert into customers (customerid, companyname) values (@customerid, @companyname)", conn)
cmd.parameters.add("@customerid", oledbtype.char, 5, "customerid")
cmd.parameters.add("@companyname", oledbtype.varchar, 40, "companyname")
da.insertcommand = cmd
' create the deletecommand.
cmd = new oledbcommand("delete from customers where customerid = @customerid", conn)
parm = cmd.parameters.add("@customerid", oledbtype.char, 5, "customerid")
parm.sourceversion = datarowversion.original
da.deletecommand = cmd
' create the updatecommand.
cmd = new oledbcommand("update customers set customerid = @customerid, companyname = @companyname where customerid = @oldcustomerid", conn)
cmd.parameters.add("@customerid", oledbtype.char, 5, "customerid")
cmd.parameters.add("@companyname", oledbtype.varchar, 40, "companyname")
parm = cmd.parameters.add("@oldcustomerid", oledbtype.char, 5, "customerid")
parm.sourceversion = datarowversion.original
da.updatecommand = cmd
return da
end function
以下两行
parm = cmd.parameters.add("@customerid", oledbtype.char, 5, "customerid")
parm.sourceversion = datarowversion.original
可以缩写为
cmd.parameters.add("@customerid", oledbtype.char, 5, "customerid").sourceversion = datarowversion.original
类似地当添加参数后马上进行设置参数的值时,也可以进行类似以下缩写
mydataadapter.selectcommand.parameters.add("@categoryname", oledbtype.varchar, 80).value = "toasters"
mydataadapter.selectcommand.parameters.add("@serialnum", oledbtype.integer).value = 239
(信息整理来自msdn)
