Oracle-bound variable classic Parsing

In Oracle, there are two optional parsing processes for a submitted SQL statement: Hard parsing and soft parsing. A hard parsing requires parsing, creating execution paths, optimizing access plans, and many other steps. hard explanation not only consumes a lot of CPU, but also occupies important latch resources, the expansion of the system is severely affected (that is, the release of the system is restricted), and the resulting problems cannot be solved by increasing the number of memory stick and CPU. This is because the bolts are set to access and modify some memory areas in sequence. These memory areas cannot be modified at the same time. After an SQL statement is submitted, Oracle first checks whether there are identical statements in the Shared Buffer Pool (shared pool). If yes, it only needs to perform soft analysis, otherwise, you must perform a hard analysis. The only way to allow Oracle to reuse the execution plan is to bind variables. The essence of variable binding is the substitution variable used to replace constants in SQL statements. Variable binding makes the SQL statements submitted each time identical. Normal SQL Statement: Select fname, lname, pcode from cust Where id = 674;
Select fname, lname, pcode from cust Where id = 234;
Select fname, lname, pcode from cust Where id = 332; Contains Bound variables SQL Statement: Select fname, lname, pcode from cust Where id =: cust_no;   SQL * Plus Bind variables: SQL> variable X number; SQL> Exec: = 123; SQL>Select fname, lname, pcode from cust Where id =: X;