I'm looking for a simple upsert (Update/Insert). The tables looks like this
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id | int(11) | YES | PRI | NULL | |
| name | varchar(20) | YES | | NULL | |
| email | varchar(20) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+
There is no key here. The idea is to insert if email is different, else update. The Insert on duplicate key in mysql doesn't suit the purpose.
Is there an elegant way to do this?
If you cannot add a unique key on the email column, you'll check to see if the record exists first (preferably in a transaction):
SELECT id FROM mytable WHERE email = 'my#example.com' FOR UPDATE
then update the record if it exists:
UPDATE mytable SET name = 'my name' WHERE id = ?
otherwise insert it:
INSERT INTO mytable (name, email) VALUES ('my name', 'my#example.com')
what about:
REPLACE INTO table VALUES(1,'hello', 'world#example.com');
Related
I have recently started to work with MySQL for my study job and now face following problem:
My predecessor created a textmining table of the following structure:
+------------+--------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+------------+--------------+------+-----+---------+-------+
| TokenId | int(11) | NO | PRI | 0 | |
| Value | varchar(255) | YES | | NULL | |
| Frequency | int(11) | YES | | NULL | |
| PMID | int(11) | YES | MUL | NULL | |
+------------+--------------+------+-----+---------+-------+
In the context of restructuring, I added the following column:
+------------+--------------+------+-----+---------+-------+
| NewTokenId | int(11) | YES | | NULL | |
+------------+--------------+------+-----+---------+-------+
If I now run the query:
insert into TitleToken(NewTokenId) select t.TokenId from Token as t, TitleToken as tt where t.Value = tt.Value
or even the query:
insert into TitleToken(NewTokenId) values(1);
I get following output:
ERROR 1062 (23000): Duplicate entry '0' for key 'PRIMARY'
As I said, I am relatively new to (hands-on) *SQL and it feels like a stupid mistake, but since the column NewTokenId is no primary key, not unique and even Null is YES, I thought I'd be able to insert basically anything I want.
Any hint would be appreciated... thanks in advance :)
The problem here is that you have a default value for the primary key "TokenID", if you do not insert a value for the key in your insert statement the system will automatically insert 0. However, if there is another tuple with the same value for this attribute (which is probable because the default is 0) you will get that error.
You are attempting to perform an insert into a table without providing a unique value for TokenId. By default, according to the table description, TokenId defaults to 0, you cannot have multiple identical values in that column.
I have this table in mysql called ts1
+----------+-------------+---------------+
| position | email | date_of_birth |
+----------+-------------+---------------+
| 3 | NULL | 1987-09-03 |
| 1 | NULL | 1982-03-26 |
| 2 | Sam#gmail | 1976-10-03 |
| 2 | Sam#gmail | 1976-10-03 |
+----------+-------------+---------------+
I want to drop the equal rows using ALTER IGNORE.
I have tried
ALTER IGNORE TABLE ts1 ADD UNIQUE INDEX inx (position, email, date_of_birth);
and
ALTER IGNORE TABLE ts1 ADD UNIQUE(position, email, date_of_birth);
In both cases I get
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 'IGNORE TABLE ts1 ADD UNIQUE(position, email, date_of_birth)' at line 1
I'm using mySQL 5.7.9. Any suggestions?
To do it inline against the table, given just the columns you show consider the below. To do it in a new table as suggested by Strawberry, see my pastie link under comments.
create table thing
( position int not null,
email varchar(100) null,
dob date not null
);
insert thing(position,email,dob) values
(3,null,'1987-09-03'),(1,null,'1982-03-26'),
(2,'SamIAm#gmail.com','1976-10-03'),(2,'SamIAm#gmail.com','1976-10-03');
select * from thing;
+----------+------------------+------------+
| position | email | dob |
+----------+------------------+------------+
| 3 | NULL | 1987-09-03 |
| 1 | NULL | 1982-03-26 |
| 2 | SamIAm#gmail.com | 1976-10-03 |
| 2 | SamIAm#gmail.com | 1976-10-03 |
+----------+------------------+------------+
alter table thing add id int auto_increment primary key;
Delete with a join pattern, deleting subsequent dupes (that have a larger id number)
delete thing
from thing
join
( select position,email,dob,min(id) as theMin,count(*) as theCount
from thing
group by position,email,dob
having theCount>1
) xxx -- alias
on thing.position=xxx.position and thing.email=xxx.email and thing.dob=xxx.dob and thing.id>xxx.theMin
-- 1 row affected
select * from thing;
+----------+------------------+------------+----+
| position | email | dob | id |
+----------+------------------+------------+----+
| 3 | NULL | 1987-09-03 | 1 |
| 1 | NULL | 1982-03-26 | 2 |
| 2 | SamIAm#gmail.com | 1976-10-03 | 3 |
+----------+------------------+------------+----+
Add the unique index
CREATE UNIQUE INDEX `thing_my_composite` ON thing (position,email,dob); -- forbid dupes hereafter
View current table schema
show create table thing;
CREATE TABLE `thing` (
`position` int(11) NOT NULL,
`email` varchar(100) DEFAULT NULL,
`dob` date NOT NULL,
`id` int(11) NOT NULL AUTO_INCREMENT,
PRIMARY KEY (`id`),
UNIQUE KEY `thing_my_composite` (`position`,`email`,`dob`)
) ENGINE=InnoDB AUTO_INCREMENT=5 DEFAULT CHARSET=utf8;
I have a table of this structure:
mysql> desc securities;
+-----------------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------------+-------------+------+-----+---------+-------+
| sym | varchar(19) | NO | PRI | | |
| bqn | int(11) | YES | | NULL | |
| sqn | int(11) | YES | | NULL | |
| tqn | int(11) | YES | | NULL | |
+-----------------+-------------+------+-----+---------+-------+
4 rows in set (0.01 sec)
I am trying to do a select and an update within the same query, so the reason I have chosen
insert into securities (sym, bqn, sqn , tqn) values('ANK', 50,0,1577798)
on duplicate key update bqn=bqn+50 , sqn=sqn+0 , tqn=tqn+1577798;
When I ran the above I observed it is in fact changing the values for all the other rows also.
Is this behaviour expected? I am using MySQL Database.
Your fiddle is missing the key, and the INSERT statement in the right panel (where it does not belong in the first place) is using different column names … *sigh*
Define the symbol column as PRIMARY KEY – and use the VALUES() syntax to get the values to add in the ON UPDATE part, so that you don’t have to repeat them every single time:
insert into securities
(symbol, buyerquan, sellerquan , totaltradedquan)
values('BANKBARODA', 73, 0, 4290270)
on duplicate key update
buyerquan=buyerquan+VALUES(buyerquan),
sellerquan=sellerquan+VALUES(sellerquan),
totaltradedquan=totaltradedquan+VALUES(totaltradedquan);
Works perfectly fine, result values are as to be expect from the input: http://sqlfiddle.com/#!2/21638f/1
I have the following table:
mysql> DESC my_contacts;
+----------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+----------+-------------+------+-----+---------+-------+
| id | varchar(20) | NO | PRI | | |
| location | varchar(20) | YES | | NULL | |
| city | varchar(20) | YES | | NULL | |
| state | varchar(2) | YES | | NULL | |
+----------+-------------+------+-----+---------+-------+
4 rows in set (0.01 sec)
If I do a select all I get:
mysql> SELECT * FROM my_contacts;
+----+--------------+------+-------+
| id | location | city | state |
+----+--------------+------+-------+
| 1 | Chester,NJ | NULL | NULL |
| 2 | Katy,TX | NULL | NULL |
| 3 | San Mateo,CA | NULL | NULL |
+----+--------------+------+-------+
3 rows in set (0.00 sec)
I run the following command:
INSERT INTO my_contacts (city,state)
VALUES
(SUBSTRING_INDEX(location,',',1),RIGHT(location,2));
My purpose was to populate the columns city and state with the part before the comma and the part after the comma from the location column.
But the following happened to my table:
mysql> INSERT INTO my_contacts (city,state)
-> VALUES
-> (SUBSTRING_INDEX(location,',',1),RIGHT(location,2));
Query OK, 1 row affected (0.02 sec)
mysql> SELECT * FROM my_contacts;
+----+--------------+------+-------+
| id | location | city | state |
+----+--------------+------+-------+
| | NULL | NULL | NULL |
| 1 | Chester,NJ | NULL | NULL |
| 2 | Katy,TX | NULL | NULL |
| 3 | San Mateo,CA | NULL | NULL |
+----+--------------+------+-------+
4 rows in set (0.00 sec)
I get a record and the id which is the primary key is empty. How is this possible?
I mean it is not NULL but a primary key is not supposed to be empty either right?
You defined your id field as a varchar, which is a dumb idea when you're using it to store integers. an empty field is NOT null. a zero-length string is still a valid string, and therefore a valid id value as far as your table is concerned. Try inserting ANOTHER blank string and you'll get a primary key violation:
INSERT INTO yourtable (id) VALUES (''); // will not work
The id field should be an int type. That'd disallow "empty" values.
primary keys are unique so if you alter the table, then the second row will attempt to add an empty value and fail. as a result, it will attempt the next possible value. If you want the first value not to be empty, you can set a default value.
It's not empty. It's probably an empty string. Note that the datatype is varchar(20).
Well, you didn't assign a value to the primary key field, so the default is NULL.
.
You want to modify the table so the primary key is auto_increment.
You can use a varchar as a foreign key related to another database table, but if you wish to use it as a numerical key, you should utilize a numerical data type such as int.
I know this doesn't answer the precise question regarding the primary key, but as your question does point out the fact you are also having issues parsing out the city and state from your location column, here's the query you would want to use (note you want an UPDATE to modify existing rows, not an INSERT which will add new rows rather than columns):
UPDATE my_contacts
SET
city = substr(location, 1, locate(',', location) - 1),
state = substr(location, locate(',', location) + 1);
I want to be able to insert data into t1 and have data get populated in table t2 with the primary key as a foreign key in t2.
Basically, how come in my current setup when I INSERT INTO t1 (first_name, last_name) values ( "blah", "blah"); and then do SELECT * FROM t2; t2 it says Empty Set (0.00 sec) for t2? Shouldn't it at least show the default id of 1?
t1:
+------------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+------------+------------------+------+-----+---------+----------------+
| first_name | varchar(20) | NO | | NULL | |
| last_name | varchar(20) | NO | | NULL | |
| id | int(10) unsigned | NO | PRI | NULL | auto_increment |
+------------+------------------+------+-----+---------+----------------+
t2:
+-----------+------------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-----------+------------------+------+-----+---------+-------+
| address | varchar(50) | NO | | NULL | |
| id | int(10) unsigned | NO | MUL | NULL | |
| last_name | varchar(20) | YES | | NULL | |
+-----------+------------------+------+-----+---------+-------+
In a relational database, a FOREIGN KEY is a declaration that you intend to insert values into T2 that must match an already existing value in T1, and that you want the database to refuse to perform any action that would break this relationship.
It does not mean that the database will create records on its own in order to satisfy a relationship. If you try to insert a value into T2 that does not exist in T1, the command will fail; it will not add the required record to T1.
That is the opposite of what you're suggesting, however, in which you want the foreign key values to get automatically generated. However, there's no requirement that a primary key value actually have references and, furthermore, no limit on the number of times that primary key value can be referenced — so how would the database guess what should be created in T2?
That said, if you want some of your own code to execute automatically when data is added to T1, code which can do whatever you want, you can create a trigger on T1.
No, tables won't propagate automatically. (You can however do it with triggers) You will have to insert into t2.
You can create a trigger on table t1 so that it inserts a row into t2 with the correct id and the other fields NULL
Foreign keys will not insert records for you.
DELIMITER ;;
CREATE TRIGGER insert_addr_rec BEFORE INSERT ON t1
FOR EACH ROW BEGIN
INSERT INTO t2 SET id=NEW.id, last_name=NEW.last_name
END ;;
DELIMITER ;
NB untested code