Specified cast is not valid

[CrossofIron]

Hello.
i have a problem with datareader
when i run it i get
'Specified cast is not valid ' error

string str = "select max(substr(type,instr(TYPE,'/')+1,length(type)))+1 result from DOCUMENTTYPES where type like 'DCO%'";
dOCTINCTYPETextBox.Text = DataBase.GetDataReader(str).GetString(0);

but afther changing it to this:
string str = "select max(TYPE) result from DOCUMENTTYPES where type like 'DCO%'";
dOCTINCTYPETextBox.Text = DataBase.GetDataReader(str).GetString(0);
it works without problem ,i don't know why?
but if run this query in toad it works without problem

select max(substr(type,instr(TYPE,'/')+1,length(type)))+1 result from DOCUMENTTYPES where type like 'DCO%'

help me please
thanks in advance

 

[chrissie1]

try this

DataBase.GetDataReader(str).Item(0).ToString;

What value should the first statement be returning?

What value should the second be returning?




Christiaan Baes
Belgium

"My new site" - Me

 

[CrossofIron]

there is no 'Item' of reader
i used GetDataTypeName to see return type
1)returns decimal
2)varchar2
i used to_char to convert result to char, it worked with GetString(0)
but can i return an universal result from all field types of query?(not use data conversion)

 

[chrissie1]

Sorry it must have been

DataBase.GetDataReader(str).getItem(0).ToString;


GetItem returns an object wich you can cast.



Christiaan Baes
Belgium

"My new site" - Me