I am using Delphi 7 and Access 2007.
I want to know can anyone show me how to use Parameters with SQL statements and ADO.
What is the necessary coding and so forth. Sorry I am new to Delphi .
A parameterized query is one that includes one or more parameters. A parameter is a placeholder for a value in the WHERE clause of SELECT, UPDATE, or DELETE queries.
Create a select query, and then open the query in Design view. In the Criteria row of the field you want to add a parameter to, type Like "*"&[, the text that you want to use as a prompt, and then ]&"*".
In Delphi: TQuery TQuery has a property called SQL, which is used to store the SQL statement. TQuery encapsulates one or more SQL statements, executes them and provides methods by which we can manipulate the results.
Simply set the query's SQL
, and then populate the parameters. Use parameter names that make sense to you, of course; I've just used LastName
and FirstName
for examples. I've updated to use TADOQuery
instead of just TQuery
after your edit to the question.
ADOQuery1.SQL.Clear;
ADOQuery1.SQL.Add('SELECT * FROM MyTable');
ADOQuery1.SQL.Add('WHERE LastName = :LastName AND');
ADOQuery1.SQL.Add('FirstName = :FirstName');
// Populate the parameters and open it
ADOQuery1.Parameters.ParamByName('LastName').Value := 'Jones';
ADOQuery1.Parameters.ParamByName('FirstName').Value := 'James';
ADOQuery1.Open;
// Use query results
ADOQuery1.Close;
// Populate parameters with new values and open again
// Populate the parameters and open it
ADOQuery1.Parameters.ParamByName('LastName').Value := 'Smith';
ADOQuery1.Parameters.ParamByName('FirstName').Value := 'Sam';
ADOQuery1.Open;
// Use new query results
ADOQuery1.Close;
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