SQLite Callback Functions

When executing a query on a SQLite database using the Sqlite.exec action or the sqlquery function, it is possible, from SQLite, to call back into CSPro to execute some logic functions or user-defined functions.

Calling CSPro Logic Functions

The following CSPro logic functions are available for use in SQL queries:

Logic Function Name	SQLite Function Name
timestring	cspro_timestring

For example, this SQL query would return a formatted string containing the date and time of the first CSPro release using the timestring logic function:

SELECT cspro_timestring("%c", 957528000);

Calling User-Defined Functions

When defining a user-defined function, adding the directive sql after the function keyword indicates that the SQL query can call back into CSPro logic. These functions can accept numeric or string arguments as part of the query, and can return values of those types.

For example, this function is marked with sql:

function sql string SumNumbers(numeric value1, numeric value2)
exit maketext("The sum of %v and %v is %v.", value1, value2, value1 + value2);
end;

This function can then be called as part of a SQL query:

-- result: The sum of 12.1 and 4.2 is 16.3.
SELECT SumNumbers(12.1, 4.2);