Available in: DSQL
Added in: 2.0
Description
Executes a block of PSQL code as if it were a stored procedure, optionally with input and output parameters and variable declarations. This allows the user to perform “on the fly” PSQL within a DSQL context.
Syntax
EXECUTE BLOCK [(<inparams>)] [RETURNS (<outparams>)] AS [<declarations>] BEGIN [<PSQL statements>] END <inparams> ::= paramname type = ? [, <inparams>] <outparams> ::= paramname type [, <outparams>] <declarations> ::= See PSQL::DECLARE for the exact syntax
Examples
This example injects the numbers 0 through 127 and their corresponding ASCII characters into the table ASCIITABLE:
execute block as declare i int = 0; begin while (i < 128) do begin insert into AsciiTable values (:i, ascii_char(:i)); i = i + 1; end end
The next example calculates the geometric mean of two numbers and returns it to the user:
execute block (x double precision = ?, y double precision = ?) returns (gmean double precision) as begin gmean = sqrt(x*y); suspend; end
Because this block has input parameters, it has to be prepared first. Then the parameters can be set and the block executed. It depends on the client software how this must be done and even if it is possible at all – see the notes below.
Our last example takes two integer values, smallest and largest. For all the numbers in the range smallest .. largest, the block outputs the number itself, its square, its cube and its fourth power.
execute block (smallest int = ?, largest int = ?) returns (number int, square bigint, cube bigint, fourth bigint) as begin number = smallest; while (number <= largest) do begin square = number * number; cube = number * square; fourth = number * cube; suspend; number = number + 1; end end
Again, it depends on the client software if and how you can set the parameter values.
Notes
set term #;
execute block (...) as begin statement1; statement2; end # set term ;#
In Firebird's isql client you must set the terminator to something other than “;” before you type in the EXECUTE BLOCK statement. Otherwise isql, being line-oriented, will try to execute the part you have entered as soon as it encounters the first semicolon.