Parameter has no default value, SQL Query doesn't work

Question

SELECT *
FROM Candidate
WHERE Candidate.Username = CurrentUser

CurrentUser is a global variable (string) which gets the username from the login. When I try to use the SQLQuery with a TDBGrid I get the error, Parameter CurrentUser has no default value.

unit UntVar;

interface

Var Currentuser:String;


implementation

end.

Code for the Global variable.

CurrentUser := EdtUser.Text; Code for when currentuser gains a value.

This is probably happens, because you not defining CurrentUser and trying to give it to the query. — Alexander
– Alexander, Commented Feb 18, 2014 at 15:59
So I would have to give Currentuser a value before I could use it in the query? — user3324069
– user3324069, Commented Feb 18, 2014 at 16:02

pedro.olimpio · Accepted Answer · 2014-02-21 16:52:39Z

2

You can use this Code:

  ADOQuery1.SQL.Clear();
  ADOQuery1.SQL.Add('SELECT * FROM Candidate');
  ADOQuery1.SQL.Add('WHERE Candidate.UserName = :CurrUser');
  ADOQuery1.Parameters.ParamByName('CurrUser').Value := CurrentUser;

  ADOQuery1.Open;

answered Feb 21, 2014 at 16:52

pedro.olimpio

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Comments

Ken White · Accepted Answer · 2014-02-18 16:16:20Z

0

You're not doing anything to assign the content of the global variable to the parameter. (They're not visible or connected in any way. The SQL.Text is simply a string, and the GlobalUser variable is simply a variable holding a string. You need to do something to provide the value to the SQL itself.)

You need something like this:

Query.SQL.Text := 'SELECT * FROM Candidate WHERE Candidate.UserName = :CurrUser';
Query.ParamByName('CurrUser').AsString := CurrentUser;  // Your global var
Query.Open;

edited Feb 18, 2014 at 16:16

answered Feb 18, 2014 at 16:03

Ken White

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1 Comment

user3324069 Over a year ago

As I'm using a TADOQuery I'm unsure where I would put the code or in what format/syntax

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