I have been trying to do insert / update records in a mysql table. Cannot use ON DUPLICATE KEY because i have nothing to do with the primary key.
Basically i have to update a record in the database
INSERT INTO table (city, state, gender, value) VALUES ("delhi","delhi","M",22)
If a record of that city, state, gender exists, then simply overwrite the value.
Can i achieve this without sending two queries from the programming language
actually you can still use ON DUPLICATE KEY, just add a unique index on the following columns, eg
ALTER TABLE tbl_name ADD UNIQUE index_name (city, state, gender)
your query now will be,
INSERT INTO table (city, state, gender, value)
VALUES ('delhi','delhi','M', 22)
ON DUPLICATE KEY UPDATE value = 22
Keep in mind that constructs such as ON DUPLICATE KEY and REPLACE INTO were specifically designed to prevent exactly that. The only other way to prevent two queries from your application layer is by declaring a database function that does the same things.
Therefore, add either a UNIQUE(city, state, gender) key or a primary key that spans the same columns. The difference between the two lies in the value range of each column; primary keys force NOT NULL whereas UNIQUE allows for columns to be NULL.
The difference is subtle but can sometimes lead to unexpected results, because NULL values are considered to be unique. For example, let's say you have this data in your database:
nr | name
123 | NULL
If you try to insert another (123, NULL) it will not complain when you use UNIQUE(nr,name); this may seem like a bug, but it's not.
Related
I am trying to use a WHERE condition on an INSERT INTO statement that contains ON DUPLICATE KEY. An example of what I'm trying to achieve is below.
This SQL statement is being called by third-party software and we want to exclude some exports based on numerical values, in this case 2. So, when X != Y perform INSERT, if X == Y, don't.
INSERT INTO satellites (name, intname) VALUES ('%SATELLITE.NAME%','%SATELLITE.INTNAME%') ON DUPLICATE KEY UPDATE name='%SATELLITE.NAME%',intname='%SATELLITE.INTNAME%' WHERE '%SATELLITE.NAME%' != 2;
Use a SELECT query rather than VALUES. Then you can add a condition to ignore the name
INSERT INTO satellites (name, intname)
SELECT '%SATELLITE.NAME%' AS name, '%SATELLITE.INTNAME%'
FROM DUAL
HAVING name != 2
ON DUPLICATE KEY UPDATE name = VALUES(name), intname = VALUES(intname)
Note that in the ON DUPLICATE KEY UPDATE clause you don't need to specify the assignment to the unique key column, since it's not going to change (since that's what is duplicate). But I didn't know which one is the unique key, so I didn't remove it.
DUAL is a placeholder for a table name when you're just selecting literal values.
I am guessing you want the internal name from the satelites and search for it in your table
INSERT INTO satellites (name, intname) VALUES ('%SATELLITE.NAME%','%SATELLITE.INTNAME%')
ON DUPLICATE KEY UPDATE name='%SATELLITE.NAME%',intname=(SELECT intname FROM satellites WHERE name != 2 ORDER BY intname LIMIT 1);
I have a table that contains
id | user | date | data1 | data2 ......
where id is the primary unique key.
I'm trying to write a query that can UPDATE if both user and date exist while INSERT if either one of them doesn't exist
I thought about the INSERT INTO...ON DUPLICATE KEY...UPDATE method, but that requires using the unique key, which I do have but not using.
What would be a good way to deal with this issue?
Per discussion in comments, you should make (user, date) a unique key.
This will trigger the INSERT INTO ... ON DUPLICATE KEY UPDATE query as expected, updating rows with matching user and date fields, and inserting new ones where no match is found.
The only valid option is to implement this UPSERT in the programming language that you use with mysql, because MySQL needs a unique key for both INSERT ... INTO and REPLACE.
Or to add a unique index on the user and date columns which seems to be in concordance with your business logic anyway.
I have a database: groupofficecom has two tables:
cal_events: id(Primary key), name, start_time, description,....
cf_cal_events: model_id (Primary key), col_1, col_2, col_3,....
I'm trying to execute the following code:
INSERT INTO groupofficecom.cf_cal_events (model_id,col_1,col_2,....)
SELECT groupofficecom.cal_events.ID, '0' AS col_1, '' AS col_2,....
FROM groupofficecom.cal_events
But it keeps giving me error #1062 - Duplicate entry '155' ('155' is the 'id' from cal_events) for key 'PRIMARY'
I want the primary key model_id to be the same value as id in cal_events because the table cf_cal_events is just complementary fields for cal_events (this is a program, so I can't change its database, it'll be gone on the first update)
Thank you guys!
This means there already is an entry with that id in the target table.
First, check how this can be.
Then, use one of the solutions described here as is appropriate:
"INSERT IGNORE" vs "INSERT ... ON DUPLICATE KEY UPDATE"
i.e. UPDATE or IGNORE.
You should use an ORDER BY with the select you have and the solution above to choose which entries get ignored (all but the first entry with IGNORE).
It is also possible that you want something different entirely, i.e. to use an UPDATE statement instead of an INSERT statement.
In fact I found a very good function, it's very similar to the INSERT but smarter:
REPLACE INTO database (column_1, column_2)
SELECT source_column1, 'value' AS column2
FROM table;
Or:
REPLACE INTO database (column_1, column_2)
VALUES ('value1', 'value2')
FROM table;
Works like magic!
It inserts new items to the destination table, and if it finds a row with the same primary key value, it erases it and re-inserts the new value (it works great for updating a table from another one)
I hope this solves your problem like it solved mine ;)
I am doing an insert from an imported table and adding data into multiple tables using mysql.
Basically when doing the insert there are some null fields as the data has been imported from a csv.
What I want to do is extract the data and not create multiple null entries. An example is when adding contacts which have no entries. Basically I want to have one entry in the table which can be bound to the id within the table.
How can i do this?
My current code is
Insert into Contact(FirstName, Surname, Position, TelephoneNo, EmailAddress, RegisteredDate)
Select Distinct Import.FirstName, Import.SecondName, Import.JobTitle,
Import.ContactTelNumber, Import.EmailAddress, Import.RegistrationDate
FROM Import
This basically imports and does no checks but where can I add check for this?
It's hard to infer exactly what you mean from your description. It would help if you showed a couple of example lines, one that you want included and one that you want to be excluded.
But you can add a variety of conditions in the WHERE clause of your SELECT. For example, if you just want to make sure that at least one column in Import is non-null, you could do this:
INSERT INTO Contact(FirstName, Surname, Position, TelephoneNo,
EmailAddress, RegisteredDate)
SELECT DISTINCT FirstName, SecondName, JobTitle,
ContactTelNumber, EmailAddress, RegistrationDate
FROM Import
WHERE COALESCE(FirstName, SecondName, JobTitle, ContactTelNumber,
EmailAddress, RegistrationDate) IS NOT NULL
COALESCE() is a function that accepts a variable number of arguments, and returns the first non-null argument. If all the arguments are null, it returns null. So if we coalesce all the columns, and we get a null, then we know that all the columns are null, and we exclude that row.
Re your comment:
Okay, it sounds like you want a unique constraint over the whole row, and you want to copy only rows that don't violate the unique constraint.
One way to accomplish this would be the following:
ALTER TABLE Contact ADD UNIQUE KEY (FirstName, Surname, Position, TelephoneNo,
EmailAddress, RegisteredDate);
INSERT IGNORE INTO Contact(FirstName, Surname, Position, TelephoneNo,
EmailAddress, RegisteredDate)
SELECT DISTINCT FirstName, SecondName, JobTitle,
ContactTelNumber, EmailAddress, RegistrationDate
FROM Import;
The INSERT IGNORE means if it encounters an error like a duplicate row, don't insert it, but also don't abort the insert for other rows.
The unique constraint creates an index, so it will take some time to run that ALTER TABLE, depending on the size of your table.
Also it may be impractical to have a key containing many columns. Indexes have a limit of 16 columns and 1000 bytes total in length. However, I would expect that what you really want is to restrict to one row per EmailAddress or some other subset of the columns.
I'm pretty much a complete newbie to SQL, I'm using MySQL with SQLyog. I have five fields, StudentForename, StudentSurname, StudentAge, StudentHouse and StudentID for the Primary Key. The StudentID field is set as a Primary Key and Not Null and AutoIncrement. I'm trying to use an INSERT INTO statement without having to entering the primary key - apparently I shouldn't need to, it should update itself. But it's not working, it's returning the error "Column count doesn't match value count at row 1". Here's the code I'm using. I've already set up the table, so I haven't got the code for the query that
INSERT INTO students VALUES('Harry', 'Potter', 'Slytherin', 30)
You will need to explicitly state which columns you will provide values for, otherwise it is assumed you will provide values for all columns. E.g.
INSERT INTO students (`first_name`, `last_name`, `house`, `age`) VALUES('Harry', 'Potter', 'Slytherin', 30)
(I made up column names, swap these with your columns)