引用 SPL 变量和异常处理程序的作用域

CREATE DATABASE demo;
        CREATE TABLE tracker (
        who_submitted CHAR(80), -- Show what code was running.
        value INT,              -- Show value of the variable.
        sequential_order SERIAL -- Show order of statement execution.
        );
        CREATE PROCEDURE demo_local_var()
        DEFINE var1, var2 INT;
        LET var1 = 1;
        LET var2 = 2;
        INSERT INTO tracker (who_submitted, value) 
        VALUES ('var1 param before sub-block', var1);
        BEGIN
        DEFINE var1 INT;   -- same name as global parameter.
        LET var1 = var2;
        INSERT INTO tracker (who_submitted, value) 
        VALUES ('var1 var defined inside the "IF/BEGIN".', var1);
        END
        INSERT INTO tracker (who_submitted, value) 
        VALUES ('var1 param after sub-block (unchanged!)', var1);
        END PROCEDURE;
        EXECUTE PROCEDURE demo_local_var();
        SELECT sequential_order, who_submitted, value FROM tracker 
        ORDER BY sequential_order;