MYSQL: How to make NULL or empty data default to 0 during insert
Solution 1
You can definitely use a trigger for that
Assuming that you make the field nullable
CREATE TABLE `listings` (
`ListingID` int(11) NOT NULL,
`BathsFull` int(6), <-----
PRIMARY KEY (`ListingID`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
Trigger
DELIMITER $$
CREATE TRIGGER tg_lst_insert BEFORE INSERT ON listings
FOR EACH ROW
BEGIN
SET NEW.BathsFull = IFNULL(NEW.BathsFull, 0);
END $$
DELIMITER ;
Inserting some rows
INSERT INTO `listings` VALUES(1, '');
INSERT INTO `listings` VALUES(3, 'a');
INSERT INTO `listings` VALUES(4, NULL);
INSERT INTO `listings` (ListingID) VALUES(2);
INSERT INTO `listings` VALUES(5, 3);
Result
+-----------+-----------+
| ListingID | BathsFull |
+-----------+-----------+
| 1 | 0 |
| 2 | 0 |
| 3 | 0 |
| 4 | 0 |
| 5 | 3 |
+-----------+-----------+
Solution 2
If you are explicitly setting the value to NULL in your insert, but want MySQL to replace the NULL with 0, one way to do that is to define the column to allow NULL in the CREATE TABLE
statement, and then replace the NULL with a TRIGGER
.
Something like this:
CREATE TABLE `listings` (
`ListingID` int(11) NOT NULL,
`BathsFull` int(6) NULL DEFAULT 0,
PRIMARY KEY (`ListingID`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
delimiter $$
create trigger tr_b_ins_listings before insert on listings for each row
begin
set new.BathsFull = coalesce(new.BathsFull,0);
end $$
delimiter ;
Try it for yourself in this SQL Fiddle
Solution 3
You forgot to post the INSERT queries but I'm sure the problem is there. This works as expected:
insert into listings (ListingID) values(1)
... because you omit BathsFull
so MySQL uses the defalt. This doesn't:
insert into listings (ListingID, BathsFull) values(1, null);
... because your are telling MySQL that you want NULL
.
Solution 4
You can use the default
keyword to get the default value of the column during insertion.
Example :
INSERT INTO listings(ListingID, BathsFull) VALUES (2,DEFAULT);
Solution 5
Maybe you should try this:
insert into listings (ListingID, ListingID, BathsFull)
values (@listing_id, @ListingID, isnull(BathsFull, 0)
Comments
-
bigmike7801 almost 2 years
So this seems like it would be pretty straight forward and I swear I've done this before, but for some reason it's just not working for me.
I am using
MAMP
and have a table with about 200 columns and I want about 20 of them to default to 0 if NULL or empty data is inserted into it.Here's a small example of what my table looks like as well as what I have done for columns that I want to default to 0.
CREATE TABLE `listings` ( `ListingID` int(11) NOT NULL, `BathsFull` int(6) NOT NULL DEFAULT '0', PRIMARY KEY (`ListingID`) ) ENGINE=InnoDB DEFAULT CHARSET=latin1;
So notice on
BathsFull
I have it set toNOT NULL DEFAULT '0'
the problem is that when empty data is passed to it I get a SQL error ofSQLSTATE[23000]: Integrity constraint violation: 1048 Column 'BathsFull' cannot be null
.I've also tried so that
BathsFull accepts
NULLand
DEFAULT '0', however when empty data is passed, the table showsNULL
instead of0
.Am I missing something here? Do I need to write some sort of trigger? I don't want to scrub the data in my script before putting it into the DB if I don't have to.
-
bigmike7801 about 11 yearsI'm using cakePHP for my insert scripts so it's not as easy as just changing what my insert statement looks like. That's why I want MySQL handle it.
-
DessDess about 11 yearsI'm not familiar with it so I can't really help maybe you can use Álvaro G. Vicario's solution
-
bigmike7801 about 11 yearsI gave this a shot but am getting the following error
Error: SQLSTATE[HY000]: General error: 1436 Thread stack overrun: 15168 bytes used of a 131072 byte stack, and 128000 bytes needed. Use 'mysqld --thread_stack=#' to specify a bigger stack.
-
bigmike7801 about 11 yearsPlease see comment I put under Peterm's answer.
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peterm about 11 yearsIncrease the value of thread_stack parameter to 192(256)KB. See this SO question stackoverflow.com/a/5264965/1920232 and mysql doc dev.mysql.com/doc/refman/5.0/en/…