SELECT… INSERT with NOT NULL fields - mysql

Question

I am trying to do a SELECT... INSERT into a table with constraints that prevent NULL values:
mysql> create table if not exists table1 (
-> id int not null auto_increment,
-> description varchar(45),
-> primary key (`id`)
-> );
Query OK, 0 rows affected (0.01 sec)
mysql> create table if not exists table2 (
-> id int not null auto_increment,
-> description varchar(45) not null,
-> primary key (`id`),
-> unique index `unique_desc` (`description`)
-> );
Query OK, 0 rows affected (0.02 sec)
mysql> insert ignore into table1
-> (description)
-> values("stupid thing"),
-> ("another thing"),
-> (null),
-> ("stupid thing"),
-> ("last thing");
Query OK, 5 rows affected (0.00 sec)
Records: 5 Duplicates: 0 Warnings: 0
mysql> select * from table1;
+----+---------------+
| id | description |
+----+---------------+
| 1 | stupid thing |
| 2 | another thing |
| 3 | NULL |
| 4 | stupid thing |
| 5 | last thing |
+----+---------------+
5 rows in set (0.00 sec)
Cool, we have the source (table1) and destination (table2) tables created, and the source table populated with some duplicate, null data.
If I do a normal SELECT... INSERT into the destination table, I get a column with empty string as the value:
mysql> insert ignore into table2
-> (description)
-> select description
-> from table1;
Query OK, 4 rows affected, 1 warning (0.00 sec)
Records: 5 Duplicates: 1 Warnings: 1
mysql> select * from table2;
+----+---------------+
| id | description |
+----+---------------+
| 3 | |
| 2 | another thing |
| 4 | last thing |
| 1 | stupid thing |
+----+---------------+
4 rows in set (0.00 sec)
This is bad. But some boss brogrammer led me to the answer in this question:
MySQL Insert Select - NOT NULL fields
And now this method gives me the desired result:
mysql> insert ignore into table2
-> (description)
-> select description
-> from table1
-> where description <> '' and description is not null;
Query OK, 3 rows affected (0.00 sec)
Records: 4 Duplicates: 1 Warnings: 0
mysql> select * from table2;
+----+---------------+
| id | description |
+----+---------------+
| 2 | another thing |
| 3 | last thing |
| 1 | stupid thing |
+----+---------------+
3 rows in set (0.00 sec)
Is there a way for me to get the above result without having to manually protect each field using the WHERE clause?
Thanks in advance,
K

Answer 1

This technically answers your question in that you can eliminate the nulls by a join instead of the where clause.
insert ignore into table2
(description)
select t.description from table1 t
join
(
select distinct description from table1
) t1 on (t.description=t1.description);
I am pretty sure, however, that you will need to specify a join for each field though. Off the top of my head, I can't think of a way around this.