I have the following two queries that execute one after another and work fine (I can't use on duplicate key update and hence please ignore that in this discussion as I like to understand why the following behavior happens)
delete from mytable where id=1
insert into mytable set id=1, x=2, y=3, ts=unix_timestamp()
I then tried to execute these queries in one shot by using semicolons and issuing query like
delete from mytable where id=1;insert into mytable set id=1, x=2, y=3, ts=unix_timestamp()
This also works fine. However, I start getting "Commands out of sync; you can't run this command now" in any queries issued after the above query.
I looked at the MySQL manual and it only explains in terms of results. https://dev.mysql.com/doc/refman/8.0/en/commands-out-of-sync.html
However, the above queries are for deleting and inserting records and have no result so the above explanation is not helpful.
Any idea what am I doing wrong?
Below is the table schema
CREATE TABLE IF NOT EXISTS mytable (
x int(10) unsigned default '0',
id int(10) unsigned default '0',
y int(20) unsigned default '0',
ts int(10) unsigned default '0',
unique KEY (id),
unique KEY (x, y),
KEY (x)
) ENGINE=InnoDB DEFAULT CHARSET=utf8
Related
If you have an integer field setup in MySQL, no nulls allowed, default null, and you write a query that omits this field, in Laravel the query still executes, and the default value of null isn't used, but instead written as '0'.
If I take the exact, generated query by Eloquent/query builder, and run it in MySQL, it fails, rightly stating that the field in question must have a default value.
Why is there this discrepancy? What the hell is eloquent/query builder/pdo doing?!
create table syntax below:
CREATE TABLE `chapters` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`account_id` int(10) unsigned NOT NULL,
`season_id` int(10) unsigned NOT NULL,
PRIMARY KEY (`id`),
KEY `chapters_account_id_index` (`account_id`),
KEY `chapters_season_id_index` (`season_id`)
) ENGINE=InnoDB AUTO_INCREMENT=6060 DEFAULT CHARSET=utf8
COLLATE=utf8_unicode_ci
Doing an insert and omitting account_id in MySQL, fails - as it should. Doing the same in Eloquent/Laravel, does not, despite the generated query being correct.
So I figured out what was going on. Laravel by default sets strict rules to false in config/database.php. This turns off all sorts of options regarding strict mode, such as full group bys, strict trans table.etc.
What we did is set STRICT_ALL_TABLES on our my.cnf and then enforced laravel to strict = true. This solves it.
I'm running MySQL 5.5 and found behaviour I didn't know of before.
Given this create:
CREATE TABLE `test` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(128) DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `name_UQ` (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
With these inserts:
insert into test (name) values ('b');
insert into test (name) values ('a');
And this select:
select * from test;
MySQL does something I wasn't aware of:
2 a
1 b
It sorts automatically.
Given a table with one extra, non-unique column:
CREATE TABLE `test` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`name` varchar(128) DEFAULT NULL,
`other_column` varchar(128) DEFAULT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `name_UQ` (`name`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
And the same inserts (see above), the select (see above) gives this result:
1 b NULL
2 a NULL
Which is kind of expected.
Where is the behaviour of the first query (SQL Fiddle) documented? I'd like to see more of these peculiar things.
MySQL does not sort result sets automatically. The ordering of a result set is indeterminate unless the query specifies an order by clause.
You should never rely on any sort of "implicit" ordering. Just because you see it in 1 (or 100 queries). In fact, without an order by, the same query can return results in different orders on subsequent runs (although I'll admit that this regularly occurs in other database, it is unlikely in MySQL).
Instead, add the ORDER BY. Ordering by a primary key is remarkably efficient, so you don't have to worry about performance.
I'm encountering an unexpected situation with inserting/querying particular records in the following table during periods of high contention. I believe there is a race condition in the database.
CREATE TABLE `business_objects` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`obj_id` varchar(255) DEFAULT NULL,
`obj_type` varchar(255) DEFAULT NULL,
`created_at` datetime(6) NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `index_business_objects_on_obj_type_and_obj_id`
(`obj_type`,`obj_id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
The steps to reproduce are:
Check if record exists in table using this query
SELECT *
FROM business_objects
WHERE obj_type = 'Tip'
AND obj_id = '7616904'
If this query is null, attempt to create
INSERT INTO business_objects (obj_type, obj_id)
VALUES ('Tip', '7616904')
If another thread has already created a record with the same attributes this insert will fail and raise a uniqueness MySQL error. In this scenario, I catch the error and run the same query in step 1 to get the record.
SELECT *
FROM business_objects
WHERE obj_type = 'Tip'
AND obj_id = '7616904'
The query returns an empty result.
My expectation is that if the index uniqueness constraint is violated than the record should be committed to the table. What am I missing?
my table structure is
CREATE TABLE IF NOT EXISTS `emp` (
`id` int(3) NOT NULL AUTO_INCREMENT,
`name` varchar(11) DEFAULT NULL,
`age` varchar(31) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ;
My query is :
INSERT INTO `emp` (`id`, `name`) VALUES ('1', 'prashant');
This is working with all the MYSQL versions below 5.7, but not working with MYSQL version 5.7.12-0ubuntu1
Getting error :
#1364 - Field 'age' doesn't have a default value
What is new in this version ??
Try it on mysql version below 5.7 ,you will see the difference.
Thanks :-)
It would be a huge surprise if this worked in any version of mysql at all. Copy paste this into sqlfiddle.com (mysql 5.6 or 5.5) and confirm for yourself.
age is defined as varchar(31) and not null. Thus your insert statement should have a value for that column. Or you should give it a default value. While you are at it, change it to a more appropriate data type.
CREATE TABLE IF NOT EXISTS `emp` (
`id` int(3) NOT NULL AUTO_INCREMENT,
`name` varchar(11) DEFAULT NULL,
`age` int(3) NOT NULL default 0,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=2 ;
Updated:
Thinking about this some more I think you have switched off Strict Mode in your older version of mysql
Strict mode controls how MySQL handles invalid or missing values in
data-change statements such as INSERT or UPDATE. A value can be
invalid for several reasons. For example, it might have the wrong data
type for the column, or it might be out of range. A value is missing
when a new row to be inserted does not contain a value for a non-NULL
column that has no explicit DEFAULT clause in its definition. (For a
NULL column, NULL is inserted if the value is missing.) Strict mode
also affects DDL statements such as CREATE TABLE.
So my original statement is wrong! With string mode off, the default for varchar is probably '' (not sure though never used strict mode off)
In your table age described as not null.
`age` varchar(31) NOT NULL
So, it is required field for insert.
The NOT NULL constraint enforces a field to always contain a value. This means that you cannot insert a new record, or update a record without adding a value to this field.You have to give value for age also in your insert query because it cannot be null.For eg:-
insert into emp(`id`,`name`,`age`) values('1','rahul','26')
hope this helps!!.Comment for further query
I have a table constructed by the followinng:
CREATE TABLE IF NOT EXISTS test_table (
ID int(11) NOT NULL AUTO_INCREMENT,
ProfileID int(11) NOT NULL,
ForeignID int(11) NOT NULL,
PRIMARY KEY (ProfileID,ForeignID) )
ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;
I want to do something a little peculiar though, say there are 4 records in the database:
RecA, RecB, RecC, RecD
I would like to run the following query and have the insert behavior stop when a duplicate key was encountered:
INSERT IGNORE INTO test_table (ProfileID, ForeignID) VALUES(RecE, RecF, RecA, RecB, RecG);
So the query would only insert RecE and RecF, is there a way to do this in MySQL, perhaps using ON DUPLICATE KEY? Ideally the execution would just be terminated once a duplicate has been found, I am not too familiar with SQL syntax though.
Where RecG was explicitly not inserted.