I have a table called t_home_feature with the following columns: id, type, sort_order. I then executed the following MySQL statement:
INSERT INTO t_home_feature (SELECT news_id, 'news', ( SELECT max(sort_order) + 1 FROM t_home_feature ) FROM t_news )
I then did a SELECT * FROM t_home_feature but the sort_order for all rows has a value that is equal to the number of rows in t_home_feature prior to the insert statement, instead of a value like previous row + 1.
How can I modify my insert query to achieve a previous row + 1 output?
You could turn the sort_order into an auto_increment field, which means the database will automatically increment it and you need not refer to it in your insert. This has to be a key, but not a primary key. For example, here's an example from:
http://forums.mysql.com/read.php?22,264498,264967#msg-264967
There the link has an example of a workaround:
create table ai (
id int auto_increment not null,
xx varchar(9),
key(id),
primary key (xx));
You may have to do something fancy with local variables. Perhaps something like this:
SELECT COUNT(1) INTO #maxval FROM t_home_feature;
INSERT INTO t_home_feature
SELECT news_id, 'news', #maxval:=#maxval+1 FROM t_news ;
No need to any auto increment values from tables.
I have done things like this when answering questions before. Here are four(4) examples of questions I answered in the DBA StackExchange using local variables:
https://dba.stackexchange.com/questions/29007/update-ranking-on-table/29009#29009
https://dba.stackexchange.com/questions/29016/selecting-without-repititions/29018#29018
https://dba.stackexchange.com/questions/18987/update-rank-on-a-large-table/18990#18990
https://dba.stackexchange.com/questions/10251/whats-wrong-with-this-update-rank-query10320#10320
Related
I've got the following table:
productId price
1 price_value1
2 price_value2
3 price_value3
I would like to insert a new product into the table and assign it a new productId. In this case its value equals to 4.
So I want my new table to look like so:
productId price
1 price_value1
2 price_value2
3 price_value3
4 price_value4
So as far as I understand, in order to do that I have to somehow retrieve the max value of productId and insert it using INSERT INTO mytable VALUES (productId + 1, price_value4).
But how do I find out the maximum value of productId?
I tried INSERT INTO mytable VALUES (SELECT MAX(productId) + 1 FROM mytable, price_value4) but it didn't work.
This should Work:
Select the max(productID) and price_value4 as a columns from mytable and insert the result.
INSERT INTO mytable (SELECT MAX(productId) + 1, 'price_value4' FROM mytable);
However, if you are not going to jump some number you can just add an auto increment id key to product_id and then you will have only to insert the price, the product ID will be incremented automatically..
This will do so :
ALTER TABLE mytable
MODIFY COLUMN `productId` INT(10) UNSIGNED PRIMARY KEY AUTO_INCREMENT;
you can change INT(10) with the INT(5) for example depanding on the size you want to give to your productId column
EDIT :
In return to the OP question in comments why his solution wouldn't work
Some suggetions says you have to make the SELECT statment in insert always between parenthesis
INSERT INTO mytable VALUES ( (SELECT MAX(ID)+1 FROM mytable) , price_value4)
.. In my Case it Return
(1093): You can't specify target table
'mytable' for update in FROM clause
AND HERE IS WHY (Quoting From the documentation)
When selecting from and inserting into the same table, MySQL creates
an internal temporary table to hold the rows from the SELECT and then
inserts those rows into the target table. However, you cannot use
INSERT INTO t ... SELECT ... FROM t when t is a TEMPORARY table,
because TEMPORARY tables cannot be referred to twice in the same
statement
BUT there is away to overcome by using a query instead of the table itself in the FROM, which has the effect of copying the requested table values instead of referencing the one that you are updating..
INSERT INTO mytable VALUES (
(SELECT MAX(ID)+1 FROM (SELECT * FROM mytable ) as mytmp ),
'price_value4');
OR (Quoting From the documentation)
To avoid ambiguous column reference problems when the SELECT and the
INSERT refer to the same table, provide a unique alias for each table
used in the SELECT part, and qualify column names in that part with
the appropriate alias.
INSERT INTO mytable Values ( (SELECT MAX(ID)+1 FROM mytable as mytmp) , 'price_value4')
This is a duplicate question. In order to take advantage of the auto-incrementing capability of the column, do not supply a value for that column when inserting rows.
A simple syntax to create table
CREATE TABLE Product (
productId MEDIUMINT NOT NULL AUTO_INCREMENT,
price INT NOT NULL,
PRIMARY KEY (productid)
);
While inserting supplied default or leave column as blank or supplied value as NULL. Take a look at below code snippet.
INSERT INTO Product (price) VALUES
('10'),('20'),('4'),
('30');
refer this link
I have my table schema in H2 db as follows:
create table if not exists Test ( id bigint not null,name varchar(255), primary key (id) );
alter table Test add constraint if not exists Test_NAME UNIQUE (name);
I want to insert a value for the name attribute as 'Default' if it does not exist in the table by selecting the latest id value from the table and increment it by one.
Example:
Do not insert if an entry for name = Default already exists.
ID | Name
1 | Default
Insert if an entry for name = Default does not exists.
ID | Name
1 | ABC
2 | XYZ
For the id column, find the max id and increment it by one. In this case, insert id=3 and name=Default.
My query is as follows:
INSERT INTO Test (id , name)
SELECT max(id) + 1, 'Default' from Test
WHERE NOT EXISTS (SELECT * FROM Test where name='Default');
However, it gives me an error saying:
NULL not allowed for column "ID"; SQL statement
as it applies the where condition on the inner select statement.
I also tried:
MERGE INTO Test KEY(name) VALUES (SELECT MAX(id) + 1 from Test, 'Default');
It gives an error because, merge tries to update with the new values.
If it finds 'Default', it will update the row with new id causing primary key violation.
Is there a better way to do this? How can I make the query work?
You are massively overcomplicating this. Define the id field as auto increment and place a unique index on the name field. The unique index prevents duplicate names to be inserted, while the auto increment increases the value of the id field by 1 (by default) if the insert is successful.
I updated id to auto increment and the following query work flawlessly
INSERT INTO Test (name) select * from (select 'Default') as tmp WHERE NOT EXISTS (SELECT name from Test where name='Default');
when you run your query first time, no record found in table so, it give error 'null' there, so if you add IFNULL() function there as below
INSERT INTO Test (id , name)
SELECT **IFNULL**(max(id),0) + 1, 'Default'
FROM Test
WHERE NOT EXISTS (SELECT * FROM Test where name='Default');
I know, deleting duplicates from mysql is often discussed here. But none of the solution work fine within my case.
So, I have a DB with Address Data nearly like this:
ID; Anrede; Vorname; Nachname; Strasse; Hausnummer; PLZ; Ort; Nummer_Art; Vorwahl; Rufnummer
ID is primary Key and unique.
And i have entrys for example like this:
1;Herr;Michael;Müller;Testweg;1;55555;Testhausen;Mobile;012345;67890
2;Herr;Michael;Müller;Testweg;1;55555;Testhausen;Fixed;045678;877656
The different PhoneNumber are not the problem, because they are not relevant for me. So i just want to delete the duplicates in Lastname, Street and Zipcode. In that case ID 1 or ID 2. Which one of both doesn't matter.
I tried it actually like this with delete:
DELETE db
FROM Import_Daten db,
Import_Daten dbl
WHERE db.id > dbl.id AND
db.Lastname = dbl.Lastname AND
db.Strasse = dbl.Strasse AND
db.PLZ = dbl.PLZ;
And insert into a copy table:
INSERT INTO Import_Daten_1
SELECT MIN(db.id),
db.Anrede,
db.Firstname,
db.Lastname,
db.Branche,
db.Strasse,
db.Hausnummer,
db.Ortsteil,
db.Land,
db.PLZ,
db.Ort,
db.Kontaktart,
db.Vorwahl,
db.Durchwahl
FROM Import_Daten db,
Import_Daten dbl
WHERE db.lastname = dbl.lastname AND
db.Strasse = dbl.Strasse And
db.PLZ = dbl.PLZ;
The complete table contains over 10Mio rows. The size is actually my problem. The mysql runs on a MAMP Server on a Macbook with 1,5GHZ and 4GB RAM. So not really fast. SQL Statements run in a phpmyadmin. Actually i have no other system possibilities.
You can write a stored procedure that will each time select a different chunk of data (for example by rownumber between two values) and delete only from that range. This way you will slowly bit by bit delete your duplicates
A more effective two table solution can look like following.
We can store only the data we really need to delete and only the fields that contain duplicate information.
Let's assume we are looking for duplicate data in Lastname , Branche, Haushummer fields.
Create table to hold the duplicate data
DROP TABLE data_to_delete;
Populate the table with data we need to delete ( I assume all fields have VARCHAR(255) type )
CREATE TABLE data_to_delete (
id BIGINT COMMENT 'this field will contain ID of row that we will not delete',
cnt INT,
Lastname VARCHAR(255),
Branche VARCHAR(255),
Hausnummer VARCHAR(255)
) AS SELECT
min(t1.id) AS id,
count(*) AS cnt,
t1.Lastname,
t1.Branche,
t1.Hausnummer
FROM Import_Daten AS t1
GROUP BY t1.Lastname, t1.Branche, t1.Hausnummer
HAVING count(*)>1 ;
Now let's delete duplicate data and leave only one record of all duplicate sets
DELETE Import_Daten
FROM Import_Daten LEFT JOIN data_to_delete
ON Import_Daten.Lastname=data_to_delete.Lastname
AND Import_Daten.Branche=data_to_delete.Branche
AND Import_Daten.Hausnummer = data_to_delete.Hausnummer
WHERE Import_Daten.id != data_to_delete.id;
DROP TABLE data_to_delete;
You can add a new column e.g. uq and make it UNIQUE.
ALTER TABLE Import_Daten
ADD COLUMN `uq` BINARY(16) NULL,
ADD UNIQUE INDEX `uq_UNIQUE` (`uq` ASC);
When this is done you can execute an UPDATE query like this
UPDATE IGNORE Import_Daten
SET
uq = UNHEX(
MD5(
CONCAT(
Import_Daten.Lastname,
Import_Daten.Street,
Import_Daten.Zipcode
)
)
)
WHERE
uq IS NULL;
Once all entries are updated and the query is executed again, all duplicates will have the uq field with a value=NULL and can be removed.
The result then is:
0 row(s) affected, 1 warning(s): 1062 Duplicate entry...
For newly added rows always create the uq hash and and consider using this as the primary key once all entries are unique.
I am converting data from one database to another. The target db has a table called provider with primary key provider_no varchar(6).
I'm writing an insert to copy from source table to target table, and need an incremented key for provider_no. Is there a function to return even the iterations for one insert statement?
There are a lot more columns, but the basic problem i'm trying to solve is:
INSERT INTO `target`.`provider`
(`provider_no`,
`lastUpdateDate`)
SELECT
'', --incremented value
now()
from `source`.`provider`;
Auto Increment only works for int values, but i'm not at liberty here to change the data type.
Also, the source table doesn't have a usable primary key value that I can use for this copy.
To increment the varchar, first cast it to a number (either signed, or unsigned) like so:
INSERT INTO `target`.`provider`
(`provider_no`,
`lastUpdateDate`)
SELECT
cast(the_varchar_field as signed) + 1, --incremented value
now()
from `source`.`provider`;
Example:
mysql> select cast("001" as unsigned) + 1;
+-----------------------------+
| cast("001" as unsigned) + 1 |
+-----------------------------+
| 2 |
+-----------------------------+
Sorry, i thought you wanted to increment the varchar field from the source table.
To 'emulate' an auto increment field as you want to do, we can do it with variables like this:
insert into provider
select #cnt := #cnt +1, now()
from sourceprovider, (select #cnt := 0) q;
And here's a little demo: http://sqlfiddle.com/#!9/09fd4/1
Here's a solution I just implemented. There's a unique column called did on the source table, which I can use indirectly. There's probably a more elegant way to do it, but:
create table temp_key (
key_id int auto_increment primary key,
did varchar(4));
insert into temp_key (did) select did from source.provider;
INSERT INTO target.provider
(provider_no,
lastUpdateDate)
SELECT
k.key_id,
now()
FROM source.provider d
JOIN temp_key k on d.did = k.did;
drop table temp_key;
I need to do this: On inserted record I need to store Inserted item identity and selected item identity. (Example below)
I'm using after insert trigger (basically I copy one row from one table into another and do some more modifications.
I have a table parameter like this:
DECLARE #Tempequipment TABLE
(Equipment_Id int,
DefaultEquipment_Id INT)
Then I insert into table like this:
INSERT INTO dbo.tblEquipmentType
( Name, EquipmentType_Id)
SELECT name,(SELECT Equiment_Id FROM INSERTED)
FROM dbo.tblDefaultEquipmentType
This works fine!
What I need to do is: I need to insert into #TempEquipment EquipmentTypeId's that were just ineserted (can be more than one) and DefaultEquipmentTypeId's that were just copied.
I was thinking about doing something like:
INSERT INTO dbo.tblEquipmentType
( Name, EquipmentType_Id)
Output EquipmentTypeId, DefaultEquipmentTypeId into #TempEquipment
SELECT name,(SELECT Equipment_Id FROM INSERTED)
FROM dbo.tblDefaultEquipmentType
but of course this is not going to work, since it cannot get values from select statement, and not written correctly.
Any help is appreciated!
UPDATE:
I have an Item. Item can be built on different equipment. Equipment has types (foreign key. And equipmentType has attributes (foreignkey).
So this mean that we have four tables Item->Equipment->EquipmentType->EquipmentAttribute.
I need to store default EquipmentTypes and default EquipmentAtrributes for that type.
So I also got these replationship: Equipment->DefaultEquipmentType->DefaultEquipmentAttribute.
Now, When I insert new Item and select an equipment I want to copy defaults over to real tables (EquipmentType, EquipmentAttribute).
Is it clear at least a little?
Aside from how you're trying to do this (which isn't working), what specifically are you trying to do?
It may be that this can be resolved by changing / normalizing your paradigm, instead of some kind of exotic code. For example, it looks odd to have a customers table with an orderID field in it. Unless your customers only ever order one thing... I would have expected to see a customers table, an items table, and then an orders table that joined customers with items.
Hope that makes sense -- but anyway, if not, can you post your table structure, and maybe be a little more clear on what you know ahead of time (e.g., I imagine you know who your customers are, and what they ordered...before you do the insert...yes?)
For an INSERT statement you can only access the columns which are in the insert column list, so the solution is to rewrite the statement as a MERGE statement which can access all the columns including columns which are in the INSERT target table for instance IDENTITY columns.
In the demo I've used dbo.INSERTED to emulate the virtual table INSERTED from the trigger.
USE master
GO
IF DB_ID('MergeOutputExample') IS NOT NULL
DROP DATABASE MergeOutputExample
GO
CREATE DATABASE MergeOutputExample
GO
USE MergeOutputExample
GO
DECLARE #Tempequipment TABLE
(EquipmentId int,
DefaultEquipmentId INT,
ID int);
CREATE TABLE dbo.INSERTED
(
EquipmentTypeId int PRIMARY KEY
);
CREATE TABLE dbo.tblEquipmentType
(
ID int IDENTITY(1,1),
Name varchar(50),
EquipmentTypeId int PRIMARY KEY
);
CREATE TABLE dbo.tblDefaultEquipmentType
(
EquipmentTypeId int,
DefaultEquipmentTypeId int IDENTITY(1,1) PRIMARY KEY,
Name varchar(50)
);
INSERT dbo.inserted
(
EquipmentTypeId
)
VALUES (1);
INSERT dbo.tblDefaultEquipmentType
(
EquipmentTypeId,
Name
)
VALUES (
1,
'Hammer'
);
MERGE dbo.tblEquipmentType AS ET
USING (
SELECT DE.EquipmentTypeId,
DE.DefaultEquipmentTypeId,
DE.Name
FROM dbo.tblDefaultEquipmentType DE
INNER JOIN dbo.INSERTED I
ON DE.EquipmentTypeId = I.EquipmentTypeId
) AS DET
ON ET.EquipmentTypeId = DET.EquipmentTypeId
WHEN NOT MATCHED BY TARGET
THEN INSERT
(
Name,
EquipmentTypeID
)
VALUES
(
DET.Name,
DET.EquipmentTypeID
)
OUTPUT DET.EquipmentTypeId,
DET.DefaultEquipmentTypeId,
INSERTED.ID
INTO #Tempequipment;
SELECT *
FROM #Tempequipment;
SELECT *
FROM dbo.tblEquipmentType;