Consider the following table:

create table `t1` ( `date` date, `value` int ); create table `t2` ( `date` date, `value` int ); insert into `t1` (`date`, `value`) values ("2022-01-01", 1), ("2022-03-01", 3), ("2022-04-01", 4); insert into `t2` (`date`, `value`) values ("2022-01-01", 1), ("2022-02-01", 2), ("2022-04-01", 4);

t1table is missing2022-02-01date,t2table is missing2022-03-01. I want to join these two tables to produce the following result:

| t1.date | t1.value | t2.date | t2.value | | | | | | | 2022-01-01 | 1 | 2022-01-01 | 1 | | null | null | 2022-02-01 | 2 | | 2022-03-01 | 3 | null | null | | 2022-04-01 | 4 | 2022-04-01 | 4 |

The solution is to use full connection:

select * from `t1` left join `t2` on `t2`.`date` = `t1`.`date` union select * from `t1` right join `t2` on `t2`.`date` = `t1`.`date`;

This can get the results I want. But using thewherestatement breaks everything:

select * from `t1` left join `t2` on `t2`.`date` = `t1`.`date` where `t1`.`date` > "2022-01-01" union select * from `t1` right join `t2` on `t2`.`date` = `t1`.`date` where `t1`.`date` > "2022-01-01";

I expected to get this result:

| t1.date | t1.value | t2.date | t2.value | | | | | | | null | null | 2022-02-01 | 2 | | 2022-03-01 | 3 | null | null | | 2022-04-01 | 4 | 2022-04-01 | 4 |

But I got this result:

| t1.date | t1.value | t2.date | t2.value | | | | | | | 2022-03-01 | 3 | null | null | | 2022-04-01 | 4 | 2022-04-01 | 4 |

I know what's wrong but can't find a solution. The problem is thatt1.date> "whatever" filters out all empty rows in thet1table. I've tried this method but it doesn't work:

where `t1`.`date` > "2022-01-01" or `t1`.`date` = null

where `t1`.`date` > "2022-01-01" or `t1`.`date` is null

select * from `t1` left join `t2` on `t2`.`date` = `t1`.`date` where `t1`.`date` > "2022-01-01" union select * from `t1` right join `t2` on `t2`.`date` = `t1`.`date` where `t2`.`date` > "2022-01-01";