XSLT does not guarantee the order of execution of instructions. In principle, the
sql:close instruction could be evaluated before the sql:query
instruction, which would obviously be disastrous.
In practice, Saxon's order of execution for XSLT instructions is reasonably predictable
unless you use variables, or unless you invoke stylesheet functions from within an XPath
expression. Using the SQL extension instructions within templates that are directly invoked
is thus fairly safe, but it is not a good idea to invoke them as a side-effect of computing
a variable or invoking a function. The exceptions are sql:connect and
sql:query: if you use these instructions to evaluate the content of a variable,
then of course they will be executed before any instruction that uses the value of the
variable.
