I am writing a code for a table where 1st table is id --> auto incremented and primary key
2nd table is status --> varchar
Which i want to keep totally null
And
Later on be changed as updated
By insert
I tried
Example:
Create table justcheck ( id int auto increment primary key , status varchar(1) IS NULL);
IT GAVE ME AN ERROR.
1064 : SYNTAX ERROR.
You can try to use AUTO_INCREMENT instead of AUTO INCREMENT and IS NULL is for check column is null
Create table justcheck (
id int AUTO_INCREMENT primary key ,
`status` varchar(1) NULL
);
INSERT INTO justcheck(status) VALUES (NULL)
Related
I want to create a table name Users where I should have have columns User, cookieID, sessionID, Geo and then I want to first three columns to have some random unique value assigned automatically. I tried to make all three columns AUTO_INCREMENT with User column PRIMARY and 'cookieIDandsessionIDcolumnUNIQUE`. The SQL code is:
CREATE TABLE `users` ( `User` VARCHAR(20) NOT NULL AUTO_INCREMENT ,
`cookieID` INT(20) NULL DEFAULT NULL AUTO_INCREMENT ,
`sessionID` INT(20) NULL DEFAULT NULL AUTO_INCREMENT ,
`Geo` VARCHAR(30) NULL DEFAULT NULL ,
PRIMARY KEY (`User`), UNIQUE (`cookieID`), UNIQUE (`sessionID`), UNIQUE (`Geo`));
But, it did not work because only one column can be declared as AUTO_INCREMENT which must be PRIMARY.
What is the another approach to do this?
Since the auto-increment cannot be applied to multiple to rows and there no option for sequence in MySQL. You can use triggers for the unique update of the row with datetime.
Change to table creation to be of single auto-increment row.
CREATE TABLE `users` ( `User` VARCHAR(20) NOT NULL,
`cookieID` INT(20) NULL DEFAULT NULL,
`sessionID` INT(20) NULL DEFAULT NULL AUTO_INCREMENT ,
`Geo` VARCHAR(30) NULL DEFAULT NULL,
PRIMARY KEY (`User`), UNIQUE (`cookieID`), UNIQUE (`sessionID`), UNIQUE (`Geo`));
Create a trigger on the same table as below. You can set the unique values under the SET for as many column as you want.
CREATE DEFINER=`root`#`localhost` TRIGGER `users_BEFORE_INSERT` BEFORE INSERT ON `users` FOR EACH ROW BEGIN
SET
NEW.cookieID = (SELECT curdate()+curtime());
END
Now when you insert into the table as below.
insert into `users`(`User`) values("test");
You table looks like this.
User cookieID sessionID Geo
test 20315169 0 NULL
If the value which are auto incrementing, you wanna keep both values the same. Then copy the value of one column to another during insertion time of new value.
My Query:
INSERT INTO `test` (`name`)
SELECT DISTINCT c4
FROM `imp_asset` WHERE c4 !='' ORDER BY c4 ASC;
Error Code: 1062
Duplicate entry '0' for key 'PRIMARY'
My Test table:
Field Type
id int(11) NOT NULL
name varchar(200) NULL
Try to make your table as:
mysql> CREATE TABLE test(
id int(11) NOT NULL,
name varchar(200) NULL,
PRIMARY KEY (id))
or if the table is already created then try to alter it using the ALTER statement.
alter table test modify column id INT auto_increment;
The problem is that ID is of type INT and is a primary key, but on your insert query you are not specifying any value for ID and there's no default value defined.
You have to make your ID column as an auto_increment:
alter table test modify column id int auto_increment;
Please see an example fiddle here.
I've created a table with 3 columns: postID, userID, and comment.
I have the postID as the primary key, and I am trying to make this auto-increment every time I add a new row to the table.
INSERT INTO CommentTable (postID, userID, comment) VALUES (DEFAULT, "test", "test")
When I run this query, it will run OK once but then when I run it again I get "1062 - Duplicate entry '0' for key 'PRIMARY'".
How do I properly set up an auto-increment primary key?
Here is the table structure:
DROP TABLE IF EXISTS `CommentTable`;
CREATE TABLE `CommentTable` (
`postID` int(10) NOT NULL,
`userID` varchar(10) NOT NULL,
`comment` varchar(1000) DEFAULT NULL,
PRIMARY KEY (`commentID`)
)
No need to put the field postID
INSERT INTO CommentTable (userID, comment) VALUES ("test", "test")
Edit your table as:
CREATE TABLE `CommentTable` (
`postID` int(10) NOT NULL AUTO_INCREMENT,
`userID` varchar(10) NOT NULL,
`comment` varchar(1000) DEFAULT NULL,
PRIMARY KEY (`postID`)
)
Recently I had the same issue where Auto Increment was not saved. It failed every time I tried to save it. My problem was that I had a record where the value was 0 instead of 1, so I updated that record value to a non-zero value, then tried saving the Auto Increment, and it worked.
The zero(0) value in the Primary Index field was causing the ALTER tablename to fail. Once it worked, I put the value back to 0.
Scenario:
I have a table which references two foreign keys, and for each unique combination of these foreign keys, has its own auto_increment column. I need to implement a Composite Key that will help identify the row as unique using combination of these three (one foreign keys and one auto_increment column, and one other column with non-unique values)
Table:
CREATE TABLE `issue_log` (
`sr_no` INT NOT NULL AUTO_INCREMENT ,
`app_id` INT NOT NULL ,
`test_id` INT NOT NULL ,
`issue_name` VARCHAR(255) NOT NULL ,
primary key (app_id, test_id,sr_no)
);
Of course, there has to be something wrong with my query, because of which the error thrown is:
ERROR 1075: Incorrect table definition; there can be only one auto
column and it must be defined as a key
What I am trying to achieve:
I have an Application Table (with app_id as its primary key), each Application has a set of Issues to be resolved, and each Application has multiple number of tests (so the test_id col)
The sr_no col should increment for unique app_id and test_id.
i.e. The data in table should look like:
The database engine is InnoDB.
I want to achieve this with as much simplicity as possible (i.e. avoid triggers/procedures if possible - which was suggested for similar cases on other Questions).
You can't have MySQL do this for you automatically for InnoDB tables - you would need to use a trigger or procedure, or user another DB engine such as MyISAM. Auto incrementing can only be done for a single primary key.
Something like the following should work
DELIMITER $$
CREATE TRIGGER xxx BEFORE INSERT ON issue_log
FOR EACH ROW BEGIN
SET NEW.sr_no = (
SELECT IFNULL(MAX(sr_no), 0) + 1
FROM issue_log
WHERE app_id = NEW.app_id
AND test_id = NEW.test_id
);
END $$
DELIMITER ;
You can do this with myISAM and BDB engines. InnoDB does not support this. Quote from MySQL 5.0 Reference Manual.
For MyISAM and BDB tables you can specify AUTO_INCREMENT on a secondary column in a multiple-column index. In this case, the generated value for the AUTO_INCREMENT column is calculated as MAX(auto_increment_column) + 1 WHERE prefix=given-prefix.
http://dev.mysql.com/doc/refman/5.0/en/example-auto-increment.html
I don't fully understand your increment requirement on the test_id column, but if you want an ~autoincrement sequence that restarts on every unique combination of (app_id, test_id), you can do an INSERT ... SELECT FROM the same table, like so:
mysql> INSERT INTO `issue_log` (`sr_no`, `app_id`, `test_id`, `issue_name`) SELECT
IFNULL(MAX(`sr_no`), 0) + 1 /* next sequence number */,
3 /* desired app_id */,
1 /* desired test_id */,
'Name of new row'
FROM `issue_log` /* specify the table name as well */
WHERE `app_id` = 3 AND `test_id` = 1 /* same values as in inserted columns */
This assumes a table definition with no declared AUTO_INCREMENT column. You're essentially emulating autoincrement behavior with the IFNULL(MAX()) + 1 clause, but the manual emulation works on arbitrary columns, unlike the built-in autoincrement.
Note that the INSERT ... SELECT being a single query ensures atomicity of the operation. InnoDB will gap-lock the appropriate index, and many concurrent processes can execute this kind of query while still producing non-conflicting sequences.
You can use a unique composite key for sr_no,app_id & test_id. You cannot use incremental in sr_no as this is not unique.
CREATE TABLE IF NOT EXISTS `issue_log` (
`sr_no` int(11) NOT NULL,
`app_id` int(11) NOT NULL,
`test_id` int(11) NOT NULL,
`issue_name` varchar(255) NOT NULL,
UNIQUE KEY `app_id` (`app_id`,`test_id`,`sr_no`)
) ENGINE=InnoDB ;
I have commented out unique constraint violation in sql fiddle to demonstrate (remove # in line 22 of schema and rebuild schema )
This is what I wanted
id tenant
1 1
2 1
3 1
1 2
2 2
3 2
1 3
2 3
3 3
My current table definition is
CREATE TABLE `test_trigger` (
`id` BIGINT NOT NULL,
`tenant` varchar(255) NOT NULL,
PRIMARY KEY (`id`,`tenant`)
);
I created one table for storing the current id for each tenant.
CREATE TABLE `get_val` (
`tenant` varchar(255) NOT NULL,
`next_val` int NOT NULL,
PRIMARY KEY (`tenant`,`next_val`)
) ENGINE=InnoDB ;
Then I created this trigger which solve my problem
DELIMITER $$
CREATE TRIGGER trigger_name
BEFORE INSERT
ON test_trigger
FOR EACH ROW
BEGIN
UPDATE get_val SET next_val = next_val + 1 WHERE tenant = new.tenant;
set new.id = (select next_val from get_val where tenant=new.tenant);
END$$
DELIMITER ;
This approach will be thread safe also because any insertion for the same tenant will happen sequentially because of the update query in the trigger and for different tenants insertions will happen parallelly.
Just add key(sr_no) on auto-increment column:
CREATE TABLE `issue_log` (
`sr_no` INT NOT NULL AUTO_INCREMENT ,
`app_id` INT NOT NULL ,
`test_id` INT NOT NULL ,
`issue_name` VARCHAR(255) NOT NULL ,
primary key (app_id, test_id,sr_no),
key (`sr_no`)
);
Why don't you try to change the position of declare fields as primary key, since when you use "auto_increment" it has to be referenced as the first. Like in the following example
CREATE TABLE `issue_log` (
`sr_no` INT NOT NULL AUTO_INCREMENT ,
`app_id` INT NOT NULL ,
`test_id` INT NOT NULL ,
`issue_name` VARCHAR(255) NOT NULL ,
primary key (sr_no,app_id, test_id)
);
I meet some errors when using auto_increment in MySQL.
code is here:
user_id bigint(20) unsigned not null auto_increment=1000
but when I try
user_id bigint(20) unsigned not null auto_increment
it works. why?
This should work:
create table test1 (
id int unsigned not null auto_increment,
primary key (id)
)auto_increment=100;
Are you trying to seed the auto increment number?
If so, the syntax is part of the CREATE|ALTER TABLE command.
See http://dev.mysql.com/doc/refman/5.5/en/example-auto-increment.html
This happens because auto increment is set for the table and not a particular column.
So to start from 1000,
Create a table column with just auto_increment
And then alter the table using
ALTER TABLE your_table_name AUTO_INCREMENT=1000;
auto increment of mysql is only +1 value.
look at this http://dev.mysql.com/doc/refman/5.0/en/example-auto-increment.html