dba基礎課程：Oracle PL/SQL變量、常量、流程控制、循環(huán)語句

定義變量和常量

<變量名> <數(shù)據(jù)類型>[(長度):=<初始值>];

var_name int;

var_name2 varchar2(20);

var_name3 numeric:=3;

定義常量

<變量名> constant <數(shù)據(jù)類型>:=<常量值>;

con_name constant integer:=3;

流程控制

1.if語句

if then

plsql_sentence;

elseif then

plsql_sentence;

else

plsql_sentence;

end;

2.case語句

case

when then plsql_sentence;

when then plsql_sentence;

.......

when then plsql_sentence;

[else plsql_sentence;]

end case;

循環(huán)語句

1.loop

loop語句先執(zhí)行一次循環(huán)體，然后再判斷exit when關鍵字后面的條件表達式的值true還是false，如果是true退出循環(huán)體，否則繼續(xù)執(zhí)行循環(huán)體

loop

plsql_sentence;

exit when end_condition_exp;

end loop;

例子：

declare

sum int := 0;

i int := 0;

begin

loop

i:= i+1;

sum := sum + i;

exit when i= 100;

end loop;

end;

2.while語句

while condition loop

plsql_sentence;

end loop;

3.for語句

for counter in [reverse] min..max loop

plsql_sentence;

end loop;

默認情況下計數(shù)器的值會循環(huán)遞增，reverse關鍵字使計數(shù)器會隨著循環(huán)器遞減

for i in 1..100 loop

dbms_output.put_line(i);

end loop;