語法寫道
if condition then
statements;
[elsif condition then
statements;]
[else
statements;]
end if; 示例
declare
v_age number(3);
begin
select age into v_age from user
where lower(name) = lower('&&name');
if v_age < 20 then
update user set age = v_age*2 where lower(name) = lower('&&name');
elsif v_age < 40 then
update user set age = v_age*3 where lower(name) = lower('&&name');
else
update user set age = v_age/2 where lower(name) = lower('&&name');
end if;
end;
語法寫道
[單一條件]
case selector
when expression1 then sequence_of_statements1;
when expression1 then sequence_of_statements2;
...when expression1 then sequence_of_statementsn;
[else sequence_of_statementsn+1;]
end case;
[多條件]
case
when selector_condition1 then sequence_of_statements1;
when selector_condition2 then sequence_of_statements2;
...when selector_conditionn then sequence_of_statementsn;
[else sequence_of_statementsn+1;]
end case; 示例
declare
v_uid user.uid%type;
begin
v_uid := &id;
case v_uid
when 1 then update user set age = 20 where uid = v_uid;
when 2 then update user set age = 40 where uid = v_uid;
else
dbms_out.put_line('不存在該使用者');
end case;
end;
declare
v_uid user.uid%type;
begin
v_uid := &id;
case
when v_uid == 1 then update user set age = 20 where uid = v_uid;
when v_uid == 2 then update user set age = 40 where uid = v_uid;
else
dbms_out.put_line('不存在該使用者');
end case;
end;
語法寫道
loop
statement1;
exit [when condition];
end loop;
使用該語句statement1至少會被執行一次。相當於do...while
示例
delcare
i int :=1;
begin
loop
update user set createdate = sysdate where uid = i;
exit when i = 10 ;
i := i+1;
end loop;
commit;
end;
語法寫道
while condition loop
statement1;
statement2;
...end loop; 示例
declare
i int := 1;
begin
while i <= 10 loop
update user set createdate = sysdate where uid = i;
i := i+1;
end loop;
commit;
end;
語法寫道
for counter in [reverse]
min_bound..upper_bound loop
statement1;
statement1;
...end loop;
counter : 迴圈控制變數，由oracle隱含定義，不需要顯示定義
min_bound、upper_bound ：迴圈控制變數的上下界；
預設情況下for迴圈在每執行一次後，控制變數會自增一；如果指定reverse選項，則會減一
示例
begin
for i in 1..10 loop
update user set createdate = sysdate where uid = i;
end loop;
commit;
end;
-- 該示例中的<>、<>為標號，該名稱可以自定義。
declare
result int;
begin
<>
for i in 1..10 loop
<>
for j in 1..10 loop
result := i * j;
dbms_output.put_line(result);
exit waibu when result = 10; -- 當 result=10 時，退出外部迴圈，本例中是當i=5時退出。相當於呼叫break語句
exit when j = 2; -- 當 j = 2 時，退出內部迴圈。相當於呼叫break語句
end loop neibu;
end loop waibu;
dbms_output.put_line(result);
end;
語法寫道
goto label_name;
goto語句用於跳轉到特定標號處。一般不建議使用
示例
declare
i int := 1;
begin
loop
if i = 10 then
goto jump_loop;
end if;
exit when i > 11;
dbms_output.put_line('i-->'||i); -- 這條語句是不會被執行的！
i := i+1;
end loop;
<>
dbms_output.put_line('i == 10 ! ');
end;
null 語句不執行任何操作，並且直接將控制傳遞到下一條語句。使用null可以提高pl/sql程式的可讀性
declare
v_uid user.uid%type := &di;
v_age user.age%type;
begin
select age into v_age from user where uid = v_uid;
if v_age < 20 then
update user set age = 100 where uid = v_uid;
commit;
else
null;
end if;
end;
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