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  • Overview
  • How to proceed?
  • The steps
  • Notes
  • Example
  • 1. Declaring the data source
  • 2. Declaring the variables
  • 3. Preparing the query
  • 4. Values of parameters and re-execution of query
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Stored procedures
Native Oracle Connector: Running the same query several times
Native AccessesAvailable only with this kind of connection
Overview
In some cases, it may be interesting to run the same query several times while modifying one or more parameters. For example, you may want to run an Insert query several times to add several records to a file.
Several solutions can be implemented:
  1. Run the query (with HExecuteSQLQuery) as many times as necessary while modifying the requested parameters.
  2. Prepare the query to run (HPrepareSQLQuery) as well as the different parameters to modify and run the query as many times as necessary with HExecuteSQLQuery. This second solution is much faster and it optimizes the time required to browse the query result (for a Select query).
This help page explains how this second solution can be implemented.
How to proceed?

The steps

To prepare and run a query several times, you must:
  1. Declare a data source. This data source will contain the result of the SQL query.
  2. Declare the types of query variables.
    The variables are retrieved in the type specified in WLanguage. The variables are text variables by default.
    Therefore, conversions may occur between the native type of the database and the WLanguage type, causing unexpected rounding or formatting errors (Date transformed into string for example).
    Therefore, we advise you to specify the WLanguage types of the variables with great care before running the query. To do so:
    • initialize the value of the variable (simple types: integer, string, float)
    • specify the expected type with ..Type (not supported in this version)
  3. Prepare the query with HPrepareSQLQuery.
  4. Specify the value of the different parameters to take into account and run the query with HExecuteSQLQuery. Only the name of the data source corresponding to the query must be specified.
This last step must be repeated as many times as necessary.

Notes

  • HPrepareSQLQuery must be used with:
    • the name of the connection,
    • the hQueryWithoutCorrection constant.
  • The declared variables must be identical to the ones used. Otherwise, a WLanguage error occurs.
  • In the call to the stored procedure, you must use the syntax specific to the database used, including for the syntax of parameters. Therefore, for Oracle, the parameters are specified with the :ParamName syntax.
    Caution: the ":" character must be followed by at least one letter (the syntax:1 is not allowed).
    The same parameter can be used several times. In this case, the corresponding variable will be re-used.
  • To run a query without enabling the bind, the hNoBind constant must be used in HExecuteSQLQuery.
Example
An Insert query must be run several times in the PERSON table. 3 parameters are modified whenever an addition is performed:
  • the last name.
  • the first name.
  • the age.

1. Declaring the data source

The data source is used to handle the different variables that will be modified whenever the query is run:
dsInsert is Data Source

2. Declaring the variables

In this example, three variables will be modified. The three variables could be declared. However, only the age_person variable will be declared.
To specify the type of a query variable, an existing variable of the requested type can be assigned to this variable.
dsInsert.age_person = 0 // Forces the type to integer

// other solution:
// B is int
dsInsert.age_person = B

3. Preparing the query

The query will be prepared to be run several times with HPrepareSQLQuery.
HPrepareSQLQuery(dsInsert, Connection, hQueryWithoutCorrection, ...
"INSERT INTO PERSON VALUES (:lastname,:firstname,:age_person)")

4. Values of parameters and re-execution of query

All you have to do now is specify the value of the parameters for each query execution.
I is int
FOR I = 1 TO 10
dsInsert.lastname = "LastName " + I
dsInsert.firstname = "FirstName " + I
dsInsert.age_person = I
HExecuteSQLQuery(dsInsert)
END
Minimum required version
  • Version 9
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