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  • Conditions for using <Source>.FreeQuery
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Stored procedures
Frees the resources of a query (after the call to <Source>.ExecuteQuery or <Source>.ExecuteSQLQuery).
Remark: This function is based on <Source>.CancelDeclaration.
When to use <Source>.FreeQuery?
This function can be used when no other process will be using the result coming from a query. We recommend that you use this function on the queries that return an important number of lines (tens of thousands) in order to free the memory space.
Example
// Initializes the query
IF MyQuery.ExecuteQuery() = False THEN
Error("Error while initializing the query" + CR + HErrorInfo())
RETURN
END
 
// Read the first record of the query
MyQuery.ReadFirst()
WHILE NOT MyQuery.Out()
// Process on the query record
...
// Read the next record
MyQuery.ReadNext()
END
MyQuery.FreeQuery()
Syntax
<Result> = <Source>.FreeQuery()
<Result>: Boolean
  • True if the operation was performed,
  • False if a problem occurs. HError is used to identify the error.
<Source>: Type corresponding to the specified source
Name of a query or a data source associated with a query (for freeing resources after the call to <Source>.ExecuteQuery or <Source>.ExecuteSQLQuery).
Remarks

Conditions for using <Source>.FreeQuery

This function must be used ONLY when the query is not required anymore!
In the following example, <Source>.FreeQuery is used too soon: the table will be completely wrong. Indeed, BuildBrowsingTable (used to populate the Table control) is run in background task in a parallel process. Therefore, <Source>.FreeQuery will operate before the Table control is entirely filled, making this control unusable.
Test.ExecuteSQLQuery("select * from customer")
BuildBrowsingTable(TABLE_Table1, "test")
Test.FreeQuery()

Remark: The problem can also occur with a "data source" variable. A "data source" variable declared locally in a process (button click, procedure, method, etc.) ONLY exists during the execution of this code. For this reason, a "warning" is displayed when you are using this type of data source: "the data source will be destroyed at the end of this code".
Component: wd270hf.dll
See also
Minimum version required
  • Version 25
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