mysql 中的条件语句

2019独角兽企业重金招聘Python工程师标准>>>

1.  if if else
delimiter $$
create procedure test_1(in in_params int)
begin
declare var1 int;
set var1=in_params+1;
if var1=0 then
  insert into test2(username,age) values('Ruby lin',28);
end if;
if in_params=0 then
  update test2 set age=age+1 where username='Ruby1';
else
  update test2 set age=age+2 where username='Ruby1';
end if;
end$$
调用:call test_1(0);

2.case指令　在很多语言中我们都会看到switch case default
可以mysql里case when then else
delimiter $$
create procedure test_2(in in_params int)
begin
declare var1 int;
set var1=in_params+1;
case var1
    when 0 then insert into test2(username,age) values('Ruby qiu',21);
    when 1 then insert into test2(username,age) values('Ruby lin',28);
    else insert into test2(username,age) values('Ruby qiu',21);
end case;
end$$
调用call test_2(0);

3.while ... end while
delimiter $$
create procedure p14()
begin
declare v int;
set v=0;
while v<5 do
    insert into t values(v);
end while;
end$$
调用call p14();

4.repeat ... end repeat
delimiter $$
create procedure p15()
begin
declare v int;
set v=0;
repeat
    insert into t values(v);
    set v=v+1;
    until v>=5;
end repeat;
end$$
调用:call p15();
还有LOOP END LOOP GOTO　我不喜欢这些　所以也不建议用

转载于:https://my.oschina.net/chenlei123/blog/155277