Query.Open() Method
Version: Available or changed with runtime version 1.0.
Runs a query object and generates a data set that can be read. The following code shows the syntax of the OPEN method. Query is a variable of the Query data type that specifies the query object.
Syntax
[Ok := ] Query.Open()
Parameters
Query
Type: Query
An instance of the Query data type.
Return Value
[Optional] Ok
Type: Boolean
true if the operation was successful; otherwise false. If you omit this optional return value and the operation does not execute successfully, a runtime error will occur.
Remarks
When the Open method is called, the query is executed and the Query variable is put in a state in which the resulting dataset can be read by the Read method. The Open method has the following behavior:
To apply filters for the SetFilterS method or SetRange method, you call the SetFilterS method or SetRange method before the Open method.
To read a row from the dataset, you must call the Open method before the Read method, as shown in the following code example.
Query.SetFilter(Column1, String); Query.Open; Query.Read;To close an open query and return it to the initialized state, you can call the Close method. However, you can call the Open method multiple times without calling the Close method because the Open method implicitly calls the Close method if the query dataset is currently in an opened state.
If the Open method is called on a query that is already in the opened or in the reading state, then the query dataset is closed, and then the query is executed again. To continue to loop through the dataset, the Read method must be called again. The next Read method call returns the first row in the dataset, as shown in the following code example.
// Opens the query and generates a dataset. Query.Open; Query.Read; // Closes the query and reopens it. Query.Open; // Reads the first row in the new dataset. Query.Read;Open method does not clear any filters that were set by the SetFilter or SetRange methods on a previous Open call. If you want to clear the filters, then you must call the Clear method on the query variable.
Query.SetFilter(Column1, String); Query.Open; Query.Read; Clear(query); Query.Open; Query.Read;You are required to call the Open method before the SaveAsXML Method or SaveAsCSV Method. The SaveAsXML and SaveAsCSV methods automatically close the current query dataset and initialize a new instance of the query.
Example
The following example demonstrates how to use the Open method on a query. The example code sets filters on the query, opens the query, and then reads the dataset. For each row in the dataset, a message box is displayed that contains the values of the columns in the row.
This example requires that you create a query called Customer_SalesQuantity that links table 18 Customer with table 37 Sales Lines from the CRONUS International Ltd. demonstration database. Include columns for the Name and No. fields from the Customer table and the Quantity field from Sales Lines table.
The following AL code opens the query, reads each row of the dataset, and then displays a message that uses the content of the row. You can add the code to a codeunit, and then run the codeunit to see the results.
var
MyQuery: Query "Customer SalesQuantity";
Text000: Label 'Customer name = %1, Quantity = %2';
begin
// Sets a filter to display only sales quantities greater than 20.
MyQuery.SetFilter(Quantity, '>20');
// Runs the query.
MyQuery.Open;
// Reads each row in the dataset and displays a message with column values.
// Stops reading when there are no more rows remaining in the dataset (Read is False).
while MyQuery.Read do
begin
Message(Text000, MyQuery.Name, MyQuery.Quantity);
end;
MyQuery.Close;
end;
When the code is run, a message that resembles the following appears for each row in the dataset:
Customer name = The Device Shop, Quantity = 30