PL/SQL 学习笔记1

PL/SQL 不具备输入输出的能力
但是可以依靠环境来执行数值的输入输出给PL/SQL 块
SQLPLUS 环境用substitution variables 和 host(bind) variable 来传入数值给PL/SQL块
substitution variable: such as a preceding ampersand  &a
host(bind) variable : such as a  preceding colon :x
替代变量可以不用声明，但是会在执行的时候有一个交互式提示
绑定变量需要声明并且赋值的时候用exec语句
SQL> var df df
Usage: VAR[IABLE] [ <variable> [ NUMBER | CHAR | CHAR (n [CHAR|BYTE]) |
VARCHAR2 (n [CHAR|BYTE]) | NCHAR | NCHAR (n) |
NVARCHAR2 (n) | CLOB | NCLOB | REFCURSOR |
BINARY_FLOAT | BINARY_DOUBLE ] ]
SQL> var a number
SQL> exec :a :=123
PL/SQL procedure successfully completed.
SQL> edit
Wrote file afiedt.buf
1 declare
2 begin
3 dbms_output.put_line('result='||'&a'||:a);
4* end;
SQL> /
Enter value for a: i love u
old 3: dbms_output.put_line('result='||'&a'||:a);
new 3: dbms_output.put_line('result='||'i love u'||:a);
result=i love u123
PL/SQL procedure successfully completed.
SQL>