MYSQL:如果变量不是null，如何根据变量将变量插入表中

Question

我的示例代码：

SET @VARIABLE1 := 'Heyho';
create table Test(id integer, title varchar(100));
insert into Test(id, title) values(1, "Hello");
insert into Test(id, title) values(2, (SELECT @VARIABLE1));
insert into Test(id, title) values(3, (SELECT @VARIABLE2 WHERE @VARIABLE2 IS NOT NULL));
select * from Test;

我的实际结果：

id  title
1   Hello
2   Heyho
3   NULL

我的预期结果：

id  title
1   Hello
2   Heyho

如果@VARIABLE2不是空，我只想插入ID为3的行

Answer 1

由于Akina的评论，正确的代码是：

SET @VARIABLE1 := 'Heyho';
create table Test(id integer, title varchar(100));
insert into Test(id, title) values(1, "Hello");
insert into Test(id, title) SELECT 2, @VARIABLE1 WHERE @VARIABLE1 IS NOT NULL;
insert into Test(id, title) SELECT 3, @VARIABLE2 WHERE @VARIABLE2 IS NOT NULL;
select * from Test;

它现在起作用了，我得到了预期的结果！