I have a table storing basic article information:
table name: cms_articles
[article_id] , [article_header] , [article_content]
1 , test , test content
2 , another , something
3 , article , text
I am using the following SQL to swap the article ID's of two articles:-
"UPDATE cms_articles SET article_id=99999 WHERE article_id=".$article_id1
"UPDATE cms_articles SET article_id=".$article_id1." WHERE article_id=".$article_id2
"UPDATE cms_articles SET article_id=".$article_id2." WHERE article_id=99999"
So I am simply swapping their ID's while using a temporary ID of 99999 while the swap occurs.
This works, but then when I add a new article to the table it sets the ID to 100000 automatically thanks to the autoincrement, despite the highest article_id actually being 3!
To what effect are you swapping primary keys?
No wait it doesn't matter.
As SQL is a declarative programming language and not a procedural one.
Swapping a 'primary key' is wrong and correcting you here will insure an innocent passerby doesn't adopt your laissez-faire to good design principles.
First get current autoincrement value with these query:
SELECT AUTO_INCREMENT
FROM information_schema.tables
WHERE table_name = 'table_name'
AND table_schema = DATABASE( ) ;
Then make your id swap. And then set autoincrement value back to its previous value like #DevZer0 wrote:
ALTER TABLE MY_TABLE AUTO_INCREMENT = $previous_value
Execute the alter table statement and set the auto_increment value
$sql = "ALTER TABLE MY_TABLE AUTO_INCREMENT = 3";
Related
How can I reset the AUTO_INCREMENT of a field?
I want it to start counting from 1 again.
You can reset the counter with:
ALTER TABLE tablename AUTO_INCREMENT = 1
For InnoDB you cannot set the auto_increment value lower or equal to the highest current index. (quote from ViralPatel):
Note that you cannot reset the counter to a value less than or equal
to any that have already been used. For MyISAM, if the value is less
than or equal to the maximum value currently in the AUTO_INCREMENT
column, the value is reset to the current maximum plus one. For
InnoDB, if the value is less than the current maximum value in the
column, no error occurs and the current sequence value is not changed.
See How can I reset an MySQL AutoIncrement using a MAX value from another table? on how to dynamically get an acceptable value.
SET #num := 0;
UPDATE your_table SET id = #num := (#num+1);
ALTER TABLE your_table AUTO_INCREMENT =1;
Simply like this:
ALTER TABLE tablename AUTO_INCREMENT = value;
Reference: 13.1.9 ALTER TABLE Statement
There is a very easy way with phpMyAdmin under the "operations" tab. In the table options you can set autoincrement to the number you want.
The best solution that worked for me:
ALTER TABLE my_table MODIFY COLUMN ID INT(10) UNSIGNED;
COMMIT;
ALTER TABLE my_table MODIFY COLUMN ID INT(10) UNSIGNED AUTO_INCREMENT;
COMMIT;
It's fast, works with InnoDB, and I don't need to know the current maximum value!
This way. the auto increment counter will reset and it will start automatically from the maximum value exists.
The highest rated answers to this question all recommend "ALTER yourtable AUTO_INCREMENT= value". However, this only works when value in the alter is greater than the current max value of the autoincrement column. According to the MySQL 8 documentation:
You cannot reset the counter to a value less than or equal to the value that is currently in use. For both InnoDB and MyISAM, if the value is less than or equal to the maximum value currently in the AUTO_INCREMENT column, the value is reset to the current maximum AUTO_INCREMENT column value plus one.
In essence, you can only alter AUTO_INCREMENT to increase the value of the autoincrement column, not reset it to 1, as the OP asks in the second part of the question. For options that actually allow you set the AUTO_INCREMENT downward from its current max, take a look at Reorder / reset auto increment primary key.
As of MySQL 5.6 you can use the simple ALTER TABLE with InnoDB:
ALTER TABLE tablename AUTO_INCREMENT = 1;
The documentation are updated to reflect this:
13.1.7 ALTER TABLE Statement
My testing also shows that the table is not copied. The value is simply changed.
Beware! TRUNCATE TABLE your_table will delete everything in your your_table.
You can also use the syntax TRUNCATE table like this:
TRUNCATE TABLE table_name
ALTER TABLE news_feed DROP id
ALTER TABLE news_feed ADD id BIGINT( 200 ) NOT NULL AUTO_INCREMENT FIRST ,ADD PRIMARY KEY (id)
I used this in some of my scripts. The id field is dropped and then added back with previous settings. All the existent fields within the database table are filled in with the new auto increment values. This should also work with InnoDB.
Note that all the fields within the table will be recounted and will have other ids!!!.
It is for an empty table:
ALTER TABLE `table_name` AUTO_INCREMENT = 1;
If you have data, but you want to tidy up it, I recommend to use this:
ALTER TABLE `table_name` DROP `auto_colmn`;
ALTER TABLE `table_name` ADD `auto_colmn` INT( {many you want} ) NOT NULL AUTO_INCREMENT FIRST ,ADD PRIMARY KEY (`auto_colmn`);
To update to the latest plus one id:
ALTER TABLE table_name AUTO_INCREMENT =
(SELECT (id+1) id FROM table_name order by id desc limit 1);
Edit:
SET #latestId = SELECT MAX(id) FROM table_name;
SET #nextId = #latestId + 1;
ALTER TABLE table_name AUTO_INCREMENT = #nextId;
Not tested please test before you run*
Warning: If your column has constraints or is connected as a foreign key to other tables this will have bad effects.
First, drop the column:
ALTER TABLE tbl_name DROP COLUMN column_id
Next, recreate the column and set it as FIRST (if you want it as the first column I assume):
ALTER TABLE tbl_access ADD COLUMN `access_id` int(10) NOT NULL PRIMARY KEY AUTO_INCREMENT FIRST
As of MySQL 5.6 the approach below works faster due to online DDL (note algorithm=inplace):
alter table tablename auto_increment=1, algorithm=inplace;
SET #num := 0;
UPDATE your_table SET id = #num := (#num+1);
ALTER TABLE your_table AUTO_INCREMENT =1;
ALTER TABLE tablename AUTO_INCREMENT = 1
Try to run this query:
ALTER TABLE tablename AUTO_INCREMENT = value;
Or try this query for the reset auto increment
ALTER TABLE `tablename` CHANGE `id` `id` INT(10) UNSIGNED NOT NULL;
And set auto increment and then run this query:
ALTER TABLE `tablename` CHANGE `id` `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT;
The auto-increment counter for a table can be (re)set in two ways:
By executing a query, like others already explained:
ALTER TABLE <table_name> AUTO_INCREMENT=<table_id>;
Using Workbench or another visual database design tool. I am going to show in Workbench how it is done - but it shouldn't be much different in other tools as well. By right clicking over the desired table and choosing Alter table from the context menu. On the bottom you can see all the available options for altering a table. Choose Options and you will get this form:
Then just set the desired value in the field Auto increment as shown in the image. This will basically execute the query shown in the first option.
If you're using PHPStorm's database tool you have to enter this in the database console:
ALTER TABLE <table_name> AUTO_INCREMENT = 0;
I tried to alter the table and set auto_increment to 1 but it did not work. I resolved to delete the column name I was incrementing, then create a new column with your preferred name and set that new column to increment from the onset.
I googled and found this question, but the answer I am really looking for fulfils two criteria:
using purely MySQL queries
reset an existing table auto-increment to max(id) + 1
Since I couldn't find exactly what I want here, I have cobbled the answer from various answers and sharing it here.
Few things to note:
the table in question is InnoDB
the table uses the field id with type as int as primary key
the only way to do this purely in MySQL is to use stored procedure
my images below are using SequelPro as the GUI. You should be able to adapt it based on your preferred MySQL editor
I have tested this on MySQL Ver 14.14 Distrib 5.5.61, for debian-linux-gnu
Step 1: Create Stored Procedure
create a stored procedure like this:
DELIMITER //
CREATE PROCEDURE reset_autoincrement(IN tablename varchar(200))
BEGIN
SET #get_next_inc = CONCAT('SELECT #next_inc := max(id) + 1 FROM ',tablename,';');
PREPARE stmt FROM #get_next_inc;
EXECUTE stmt;
SELECT #next_inc AS result;
DEALLOCATE PREPARE stmt;
set #alter_statement = concat('ALTER TABLE ', tablename, ' AUTO_INCREMENT = ', #next_inc, ';');
PREPARE stmt FROM #alter_statement;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END //
DELIMITER ;
Then run it.
Before run, it looks like this when you look under Stored Procedures in your database.
When I run, I simply select the stored procedure and press Run Selection
Note: the delimiters part are crucial. Hence if you copy and paste from the top selected answers in this question, they tend not to work for this reason.
After I run, I should see the stored procedure
If you need to change the stored procedure, you need to delete the stored procedure, then select to run again.
Step 2: Call the stored procedure
This time you can simply use normal MySQL queries.
call reset_autoincrement('products');
Originally from my own SQL queries notes in https://simkimsia.com/reset-mysql-autoincrement-to-max-id-plus-1/ and adapted for Stack Overflow.
delete from url_rewrite where 1=1;
ALTER TABLE url_rewrite AUTO_INCREMENT = 1;
and then reindex
ALTER TABLE `table_name` DROP `id`;
ALTER TABLE `table_name` ADD `id` INT NOT NULL AUTO_INCREMENT FIRST, ADD PRIMARY KEY (`id`) ;
Shortly,First we deleted id column then added it with primary key id again...
The best way is remove the field with AI and add it again with AI. It works for all tables.
You need to follow the advice from Miles M's comment and here is some PHP code that fixes the range in MySQL. Also you need to open up the my.ini file (MySQL) and change max_execution_time=60 to max_execution_time=6000; for large databases.
Don’t use "ALTER TABLE tablename AUTO_INCREMENT = 1". It will delete everything in your database.
$con = mysqli_connect($dbhost, $dbuser, $dbpass, $database);
$res = mysqli_query($con, "select * FROM data WHERE id LIKE id ORDER BY id ASC");
$count = 0;
while ($row = mysqli_fetch_array($res)){
$count++;
mysqli_query($con, "UPDATE data SET id='".$count."' WHERE id='".$row['id']."'");
}
echo 'Done reseting id';
mysqli_close($con);
I suggest you to go to Query Browser and do the following:
Go to schemata and find the table you want to alter.
Right click and select copy create statement.
Open a result tab and paste the create statement their.
Go to the last line of the create statement and look for the Auto_Increment=N,
(Where N is a current number for auto_increment field.)
Replace N with 1.
Press Ctrl + Enter.
Auto_increment should reset to one once you enter a new row in the table.
I don't know what will happen if you try to add a row where an auto_increment field value already exist.
I have a database table in phpMyAdmin that has:
[id, username, password, email, firstname, lastname, lastlogin]
Works just fine. The problem is it doesn't give each user an id number (they are all zeros and I want 1,2,3...). Every time a user submits their information from a form to the database, they should be assigned a number. First person to submit should be ID 1, second should be ID 2, and so on. How can I fix this in phpMyAdmin?
Thank you.
In phpMyAdmin, select your table and go to the "Structure" tab. Then on the row for your ID field, check the box under "A_I" to turn on auto increment.
To force all your records to update so they have different ID numbers, delete the ID column and then add it back again with the incrementing enabled.
Make sure that under "Index" you select "PRIMARY KEY", or else it will throw an error.
AUTO_INCREMENT should work just fine to solve your problem. Dagon posted a solution on how to alter your table which should work perfectly. If you prefer to create the table again but with AUTO_INCREMENT in place, you can use the following code:
CREATE TABLE myTable (
id INT NOT NULL AUTO_INCREMENT,
username ...,
password ...,
email ...,
firstname ...,
lastname ...,
lastlogin ...,
PRIMARY KEY (id)
)
// '...' represents the datatypes and other characteristics of the
// specific columns/fields
Let me know if that worked for you!
to add auto increment if required:
ALTER TABLE `YOUR_TABLE` CHANGE `id` `id` INT( 11 ) NOT NULL AUTO_INCREMENT
to fix the existing lack of id's
SET #count = 0;
UPDATE `YOUR_TABLE` SET `YOUR_TABLE`.`id` = #count:= #count + 1;
then
ALTER TABLE `YOUR_TABLE` AUTO_INCREMENT = 1;
I have a SQL query as follows-
"INSERT INTO users(id, rank) SELECT v.user, v.vote FROM votes v WHERE
v.assertion = '$ID' ON DUPLICATE KEY UPDATE
rank = ( CASE WHEN v.vote = '1' THEN rank+50 WHEN v.vote = '-1'
THEN rank-200 WHEN v.vote = '3' THEN rank+100 ELSE rank END)"
applied on a database with a table users with and id and rank field, and a votes table with a user and vote field. I have to update the rank of the users in the users table based on their vote.
I really like this kind of query, but I've noticed a problem: every time I execute this from my PHP script the query adds a row to the users table completely empty (with only an ID, which is A_I, and a rank of 1, when usually there would be other field as well). I can't really wrap my head around why this happens.
Any help/idea?
Your table does not have a primary key first provide a primary key to id
run this sql query
alter table user add primary key (id)
and than try it will work
There are two possible reasons :
The id column is not the primary key, and probably you table doesn't have a primary key at all.
Create a primary key like this :
alter table user add primary key (id)
If you insert an value of 0 in an auto increment column, a new id is generated. An auto incremented column must not contain the value 0.
There is also a more general problem with your approach : in fact you only insert the user id and the rank, other compulsory fields in the table (username) are missing. The insert part does not seem to be valid for this reason. If you use an insert on duplicate key update, you must make sure that the result is correct which ever of insert and update is executed.
I have a table in a mySQL database we'll call 'tbl' where the fields are:
id, userID, favorite, emailID
The id is auto incremental. The userID stores an integer. The favorite is either yes or no. The emailID stores an integer.
I am programing in PHP and would like to have one query used to query the database that checks if the userID and emailID combination exists. If it does then update the favorite field with a yes or no value that comes from a form that is passed into the query dynamically. If it does not exist then insert the combination into the database.
Therefore if I had:
<?php
$userID = 34;
$emailID = 395;
$favorite = "yes"; // could be yes or no.
I don't believe the query below is correct but gets the idea of what I am trying to do:
IF NOT EXISTS
(SELECT userID, favorite, emailID
FROM tbl
WHERE ((userID = '$userID')and(emailID = '$emailID'))
INSERT INTO tbl (userID, favorite, emailID) VALUES ('$userID', '$favorite', '$emailID')
ELSE UPDATE tbl
SET favorite = '$favorite'
WHERE ((userID = '$userID')and(emailID = '$emailID'))
(please know that I know that entering values into a query like this is a security risk, this is only to help explain my question.)
What is the best way to write the query? Can it be written with one query?
It can't be written as a single query, because the primary key isn't the two columns you're looking for - it's the id column only.
If userid and emailid are unique pairs, they should be the primary key for the table -- not the id value. ORMs typically prefer that a primary key be single column for making query construction easier but the approach suffers on performance. Anything requiring more than one columns is generally referred to as a "composite" - primary key, unique constraint/index, foreign key, etc.
The ANSI means of doing this would be a MERGE statement, but MySQL doesn't support the syntax because it already has the ON DUPLICATE KEY UPDATE and REPLACE INTO to provide the same functionality.
I would drop the redundant id column and define the primary key as the combination of (userID, emailID), which means you have exactly one record for each different combination of the two fields, which seems to be what you want. Then you can use the REPLACE INTO command, which is equivalent to an INSERT but deletes any existing record if the primary key matches.
you can do it really simply in a single call - but sprocs are bad aren't they ??
drop procedure if exists insert_update_tbl;
delimiter #
create procedure insert_update_tbl
(
in p_userID int unsigned,
in p_emailID int unsigned,
out p_id int unsigned
)
proc_main:begin
set p_id = 0;
if exists (select 1 from tbl where userID = p_userID and emailID = p_emailID) then
update tbl set favorite = 1 where userID = p_userID and emailID = p_emailID;
leave proc_main;
end if;
insert into tbl (userID, emailID, favorite) values (p_userID, p_emailID, 0);
set p_id = last_insert_id();
end proc_main #
delimiter ;
I asked this question a little earlier today but am not sure as to how clear I was.
I have a MySQL column filled with ordered numbers 1-56. These numbers were generated by my PHP script, not by auto_increment.
What I'd like to do is make this column auto_incrementing after the PHP script sets the proper numbers. The PHP script works hand in hand with a jQuery interface that allows me to reorder a list of items using jQuery's UI plugin.
Once I decide what order I'd like the entries in, I'd like for the column to be set to auto increment, such that if i were to insert a new entry, it would recognize the highest number already existing in the column and set its own id number to be one higher than what's already existing.
Does anyone have any suggestions on how to approach this scenario?
I'd suggest creating the table with your auto_increment already in place. You can specify a value for the auto_inc column, and mysql will use it, and still the next insert to specify a NULL or 0 value for the auto_inc column will magically get $highest + 1 assigned to it.
example:
mysql> create table foobar (i int auto_increment primary key);
mysql> insert into foobar values (10),(25);
mysql> insert into foobar values (null);
mysql> select * from foobar;
# returns 10,25,26
You can switch it to MySQL's auto_increment implementation, but it'll take 3 queries to do it:
a) ALTER TABLE to add the auto_increment to the field in question
b) SELECT MAX(id) + 1 to find out what you need to set the ID to
c) ALTER TABLE table AUTO_INCREMENT =result from (b)
MySQL considers altering the AUTO_INCREMENT value a table-level action, so you can't do it in (a), and it doesn't allow you to do MAX(id) in (c), so 3 queries.
You can change that with a query, issued through php, using the mysql console interface or (easiest) using phpmyadmin.
ALTER TABLE table_name CHANGE old_column_name new_column_name column_definition;
ALTER TABLE table_name AUTO_INCREMENT = highest_current_index + 1
column_definiton:
old_column_definition AUTO_INCREMENT
More info:
http://dev.mysql.com/doc/refman/5.1/en/alter-table.html
http://dev.mysql.com/doc/refman/5.1/en/create-table.html
EDIT
Always use mysql_insert_id or the appropiate function of your abstraction layer to get the last created id, as LAST_INSERT_ID may lead to wrong results.
No, stop it. This isn't the point of auto_increment. If you aren't going to make them ordered by the id then don't make them auto_increment, just add a column onto the end of the table for ordering and enjoy the added flexibility it gives you. It seems like you're trying to pack two different sets of information into one column and it's really only going to bite you in the ass despite all the well-meaning people in this thread telling you how to go about shooting yourself in the foot.
In MySQL you can set a custom value for an auto_increment field. MySQL will then use the highest auto_increment column value for new rows, essentially MAX(id)+1. This means you can effectively reserve a range of IDs for custom use. For instance:
CREATE TABLE mytable (
id INT UNSIGNED PRIMARY KEY AUTO_INCREMENT,
col1 VARCHAR(256)
);
ALTER TABLE mytable AUTO_INCREMENT = 5001;
In this schema all ids < 5001 are reserved for use by your system. So, your PHP script can auto-generate values:
for ($i=1; $i<=56; $i++)
mysql_query("INSERT INTO mytable SET id = $i, col1= 'whatevers'");
New entries will use the non-reserved range by not specifying id or setting it to null:
INSERT INTO mytable SET id = NULL, col1 = 'whatevers2';
-- The id of the new row will be 5001
Reserving a range like this is key - in case you need more than 56 special/system rows in the future.
ALTER TABLE <table name> <column name> NOT NULL AUTO_INCREMENT
More info:
AUTO_INCREMENT Handling in InnoDB
Server SQL Modes