I can't figure out why my alter table query throws an error. Currently, this is a (DATETIME) column with default value NULL.
My wish is to alter it so datetime value gets automatically populated when I update a row. I'm trying to write an alter statement, but I can't figure out why mine is throwing the error.
My alter statement
ALTER TABLE `mydb`.`orders` CHANGE COLUMN `date_u` DATETIME NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP '{}';
And this is the error that I'm getting
16:28:34 ALTER TABLE `mydb`.`orders` CHANGE COLUMN `date_u` DATETIME NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP '{}' Error Code: 1064. You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP '{}'' at line 1 0.00041 sec
I'm using MySQL version 5.7
The CHANGE COLUMN alteration is used when you might want to change the name of the column, and requires you to provide the new name after the old name. If you're not renaming the column, you have to provide the name twice. Your command tries to rename the date_u column to DATETIME, and it's missing the datatype before the NULL keyword.
Use MODIFY COLUMN instead. It's the same, but doesn't allow renaming, so doesn't require you to give the column name twice.
ALTER TABLE `mydb`.`orders` MODIFY COLUMN `date_u` DATETIME NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP;
I'm also not sure what you intended with '{}' at the end, but I don't think it's valid syntax, either, so I've removed it.
You're missing to name the new column.
change this:
ALTER TABLE `mydb`.`orders`
CHANGE COLUMN `date_u` DATETIME NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP '{}';
into this:
ALTER TABLE `mydb`.`orders`
CHANGE COLUMN `date_u` `date_u` DATETIME NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP;
Notice the column name is typed twic, because you want the column name to stay the same, formerly here's the change column syntax:
ALTER TABLE `table_name`
CHANGE COLUMN `column_name` `column_new_name` (...);
Or, you can just you modify column syntax:
ALTER TABLE `mydb`.`orders` MODIFY COLUMN `date_u` DATETIME NULL DEFAULT NULL ON UPDATE CURRENT_TIMESTAMP;
Ps: I don't get what you mean by '{}' so I removed it because I think it's not a valid syntax.
Hope I pushed you further.
Related
Basically I want to add a new updatedTime column so that it auto set to current_timestamp on updating and creating. Also I want to set the updatedTime column to null for existing rows.
So I try something like below:
Add new column and make it default to null
Set the new column default to current_timestamp afterward
alter table A
add column updatedTime timestamp null
default null on update current_timestamp;
alter table A
alter column updatedTime set default current_timestamp;
The reason is because my table is huge around 7 million rows and it's on live database as well so I try to optimise my query. By doing it this way, I just need to loop through the whole table once for the first query. The second query will only change the table config file.
So I am able to run the first query but the second one got syntax error.
EDIT:
My database is mysql server 5.7
I already have a table, simplified example:
CREATE TABLE t (c INT NOT NULL);
And I need to change column default value to NULL, so I tried:
ALTER TABLE t ALTER COLUMN c SET DEFAULT NULL;
but I got the error "Error Code: 1067. Invalid default value for 'c'".
It looks really strange, because query conforms with official docs.
I even tried to:
ALTER TABLE t ALTER COLUMN c DROP DEFAULT;
and after it to make a 'SET DEFAULT NULL' query, but the same error occurred.
It's interesting, that query like:
ALTER TABLE t ALTER COLUMN c SET DEFAULT 1;
executed without errors.
I know, that it is possible to change column default value to NULL in my case using:
ALTER TABLE t MODIFY COLUMN c INT NULL;
but this query is really slow on big tables (it is much slower, than queries like 'SET DEFAULT 1')
So, how to just change default value to NULL?
I mean, without any overhead caused by 'MODIFY COLUMN' command.
Details: MySQL x64 version 5.7.10, Win8. Tested using MySQL Workbench.
By creating column as NOT NULL you have created a CONSTRAINT - declaring that values entered into that column may never be NULL.
A default value of NULL (set to null is value not present during INSERT) would create invalid data.
As sadly nullability constraint is part of the datatype in mysql the only way to make the column nullable will be
ALTER TABLE t MODIFY COLUMN c INT NULL;
I got the following error while trying to alter a column's data type and setting a new default value:
ALTER TABLE foobar_data ALTER COLUMN col VARCHAR(255) NOT NULL SET DEFAULT '{}';
ERROR 1064 (42000): You have an error in your SQL syntax; check the
manual that corresponds to your MySQL server version for the right
syntax to use near 'VARCHAR(255) NOT NULL SET DEFAULT '{}'' at line 1
ALTER TABLE foobar_data MODIFY COLUMN col VARCHAR(255) NOT NULL DEFAULT '{}';
A second possibility which does the same (thanks to juergen_d):
ALTER TABLE foobar_data CHANGE COLUMN col col VARCHAR(255) NOT NULL DEFAULT '{}';
As a follow up, if you just want to set a default, pretty sure you can use the ALTER .. SET syntax. Just don't put all the other stuff in there. If you're gonna put the rest of the column definition in, use the MODIFY or CHANGE syntax as per the accepted answer.
Anyway, the ALTER syntax for setting a column default, (since that's what I was looking for when I came here):
ALTER TABLE table_name ALTER COLUMN column_name SET DEFAULT 'literal';
For which 'literal' could also be a number (e.g. ...SET DEFAULT 0). I haven't tried it with ...SET DEFAULT CURRENT_TIMESTAMP but why not eh?
If you want to add a default value for the already created column,
this works for me:
ALTER TABLE Persons
ALTER credit SET DEFAULT 0.0;
For DEFAULT CURRENT_TIMESTAMP:
ALTER TABLE tablename
CHANGE COLUMN columnname1 columname1 DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
CHANGE COLUMN columnname2 columname2 DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP;
Please note double columnname declaration
Removing DEFAULT CURRENT_TIMESTAMP:
ALTER TABLE tablename
ALTER COLUMN columnname1 DROP DEFAULT,
ALTER COLUMN columnname2 DROPT DEFAULT;
In case the above does not work for you (i.e.: you are working with new SQL or Azure) try the following:
1) drop existing column constraint (if any):
ALTER TABLE [table_name] DROP CONSTRAINT DF_my_constraint
2) create a new one:
ALTER TABLE [table_name] ADD CONSTRAINT DF_my_constraint DEFAULT getdate() FOR column_name;
Accepted Answer works good.
In case of Invalid use of NULL value error, on NULL values, update all null values to default value in that column and then try to do the alter.
UPDATE foobar_data SET col = '{}' WHERE col IS NULL;
ALTER TABLE foobar_data MODIFY COLUMN col VARCHAR(255) NOT NULL DEFAULT '{}';
Try this
ALTER TABLE `table_name` CHANGE `column_name` `column_name` data_type NULL DEFAULT '';
like this
ALTER TABLE `drivers_meta` CHANGE `driving_license` `driving_license` VARCHAR(30) NULL DEFAULT '';
Use this approach:-
ALTER TABLE foobar_data
CHANGE COLUMN col VARCHAR(255) NOT NULL SET DEFAULT '{}';
Hey guys I was trying to alter my tables column to take
the current time stamp on creation, the error I'm getting
is #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '( 'inspection_number' NOT NULL default CURRENT_TIMESTAMP )' at line 1
I was trying to use
ALTER TABLE `reports` (
`inspection_number` DATE NOT NULL default CURRENT_DATE
);
But I"m not seeing the error?
Seems syntax is not correct. Use below :
if adding new column inspection_number:
ALTER TABLE `reports` ADD COLUMN `inspection_number` timestamp NOT NULL default CURRENT_TIMESTAMP
if modifying existing inspection_number column:
ALTER TABLE `reports` MODIFY COLUMN `inspection_number` timestamp NOT NULL default CURRENT_TIMESTAMP
Please specify datatype of column
You're missing a MODIFY
ALTER TABLE `reports` (
MODIFY `inspection_number` NOT NULL default CURRENT_TIMESTAMP
);
ALTER TABLE `reports`
MODIFY `inspection_number` TIMESTAMP NOT NULL default CURRENT_TIMESTAMP ;
The syntax you have there is for when you create a table. When you modify a table and want to set a default value use:
ALTER TABLE table_name MODIFY col_name col_type NOT NULL DEFAULT CURRENT_TIMESTAMP;
I have a table with a column of type timestamp which defaults current_timestamp and updates to current_timestamp on every update.
I want to remove the "on update" feature on this column. How do I write the alter statement?
I tried the following:
ALTER TABLE mytable alter column time set DEFAULT now();
but this didn't work.
Pete was almost correct but used the wrong syntax for 'change':
ALTER TABLE mytable CHANGE `time` `time` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
Notice that you must repeat the column name. Also, make sure you are using backticks instead of single quotes to escape the column name time, which prevents it from being interpreted as the mysql column type of time.
By specifying the DEFAULT of CURRENT_TIMESTAMP, MySQL will no longer automatically update the column. From the MySQL Manual:
With a DEFAULT CURRENT_TIMESTAMP clause and no ON UPDATE clause, the column has the current timestamp for its default value but is not automatically updated.
You can't AFAIK use functions such as NOW() as a default.
Try
ALTER TABLE `mytable` CHANGE `time` `time` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
(Edited to add escaping and second use of field name)