本讲课程目标
1.在PL/SQL块中执行select语句
2.在PL/SQL块中执行DML语句和控制事务
3.使用隐式游标定义PL/SQL块中DML语句的输出
在PL/SQL块中"END；"表示结束PL/SQL块，但并没有结束事务，一个块可以跨越多个事务，一个事务也可以跨越多个块；PL/SQL块中不支持DDL和DCL语句，例如建表，赋予用户权限等.
一：在PL/SQL块中执行select语句
select语句在PL/SQL块中的语法结构如下
SELECT select_list
INTO {variable_name[, variable_name]...
| record_name}
FROM table
[WHERE condition];
范例：
SQL> set serveroutput on
SQL> DECLARE
2 v_first_name hr.employees.first_name%TYPE;
3 v_last_name hr.employees.last_name%TYPE;
4 BEGIN
5 SELECT first_name,last_name INTO
6 v_first_name,v_last_name FROM hr.employees
7 WHERE employee_id=100;
8 DBMS_OUTPUT.PUT_LINE(v_first_name ||' '||v_last_name);
9* END;
SQL> /
Steven King
PL/SQL procedure successfully completed
二.在PL/SQL块中执行DML语句和控制事务
可以在PL/SQL块中使用SQL的函数，自定义的序列号，字段的默认值插入数据
SQL> create table t14703a (id number(5),constraint pk_t14703a primary key(id),
2 location varchar2(30) default 'fuzhou',salary number(8,2));
Table created.
SQL> create sequence user_seq
2 increment by 1
3 start with 1
4 maxvalue 99999
5 nocache
6* nocycle
Sequence created.
SQL> select user_seq.nextval from dual;
NEXTVAL
----------
1
SQL> BEGIN
2 INSERT INTO hr.t14703a
3 (id,location,salary) VALUES
4 (user_seq.nextval,default,'6000');
5 COMMIT;
6* END;
SQL> /
PL/SQL procedure successfully completed.
SQL> select * from hr.t14703a;
ID LOCATION SALARY
---------- ---------- ----------
3 fuzhou 6000
SQL> DECLARE
2 v_salary_increase hr.t14703a.salary%TYPE := 500;
3 BEGIN
4 UPDATE hr.t14703a SET salarysalary= salary + v_salary_increase
5 WHERE id=3;
6* END;
7 /
PL/SQL procedure successfully completed.
SQL> select * from hr.t14703a;
ID LOCATION SALARY
---------- ---------- ----------
3 fuzhou 6500
三.使用隐式游标定义PL/SQL块中DML语句的输出
SQL游标，游标是私有的SQL工作区，有隐式和显式游标两个类型；oracle server使用隐式的游标来执行SQL语句
A cursor is a private SQL work area.
There are two types of cursors:
–Implicit cursors
–Explicit cursors
The Oracle server uses implicit cursors to parse and execute your SQL statements.
Explicit cursors are explicitly declared by the programmer.
4种游标的属性SQL%COUNT,SQL%FOUND,SQL%NOTFOUND,SQL%ISOPEN
SQL> VAR rownums varchar2(30)
SQL> set serveroutput on
SQL> DECLARE
2 v_a hr.t04310_a.a%TYPE := 50000;
3 BEGIN
4 delete from hr.t04310_a where a < v_a;
5 :rownums := (SQL%ROWCOUNT ||' ' || 'row deleted');
6 DBMS_OUTPUT.PUT_LINE(:rownums);
7* END;
8 /
40000 row deleted
PL/SQL procedure successfully completed.
本文出自 “月牙天冲” 博客