I'm dealing with a relational table and I've been wondering if there's a way to lower the number of queries I need to make when inserting data to the tables..
Here are the queries I currently use:
I insert the "main" values.
INSERT INTO products
(title, description, status, url)
VALUES
('some title', 'description of doom', 1, 'some-title');
We make it insert the value only if it doesn't exist already.
INSERT IGNORE INTO values
(value)
VALUES
('example value');
Since I'm not sure if the query was actually inserted, I get the id..
SELECT id
FROM
values
WHERE
value = 'example value';
Where "?" is the ID I got from the last query.
INSERT INTO link
( id_product, id_catalog, id_value )
VALUES
( 33, 1, ? );
This means that each extra value I need to add will cost 3 queries. So my question is: Is there a more efficient way to do this?
You can do this to at least drop one of the queries:
INSERT INTO link
( id_product, id_catalog, id_value )
VALUES
( 33, 1, (SELECT id
FROM values
WHERE value = 'example value') );
I basically am replacing the '?' with a sub select of the second query to get the id.
"Is there a more efficient way to do this?"
No. Not really. Creating three things takes three inserts.
You should be able to tell whether the insert succeeded with the ROW___COUNT() function from inside MySQL. If calling from another language (e.g. PHP), the mysql_query or equivalent function will return the row count.
You could use an INSERT INTO ... ON DUPLICATE KEY UPDATE statement.
This does, however, require that the primary key be one of the values for the insert, so it doesn't work on tables with an auto-increment.
Related
I have mysql query to replace some records:
REPLACE INTO product_core
(id, title, description, category_id)
VALUES (2, 'new_title', 'new_description', 33)
Can I do the same, but not providing all needed values? Example:
REPLACE INTO product_core
(id, title, description, category_id)
VALUES (2, 'new_title', 'new_description') #no category_id
Got error wrong number of values here near
I want to bulk replace many records, but I do not want to query all fields before. In this example, I want to update category_id for some records, but not for all.
REPLACE INTO product_core
(id, title, description, category_id)
VALUES (2, 'new_title_2', 'new_description_2'), #no category_id
(3, 'new_title_3', 'new_description_3', 34) #with category_id
Is it real to do this? Replace some fields for one record and other fields for second record in one query.
Or if is it real to provide special variable meaning that some fields will be the same as before replace (category_id)?
VALUES (2, 'new_title_2', 'new_description_2', #category_id_same_as_before)
Can I do the same, but not providing all needed values? Example:
REPLACE INTO product_core (id, title, description, category_id) VALUES
(2, 'new_title', 'new_description') #no category_id
Yes, the correct query is:
REPLACE INTO product_core
(id, title, description)
VALUES (2, 'new_title', 'new_description') #no category_id
EDIT: As Tom commented below the above might be misleading as for the omitted columns default values will be used, not the ones set for the record which is being replaced.
Is it real to do this? Replace some fields for one record and other fields for second record in one query.
It's not possible in MySQL. The column list is common for all the values sets.
Or if is it real to provide special variable meaning that some fields
will be the same as before replace (category_id)?
It's perhaps possible, but not straightforward and not in all MySQL versions. In the docs they say: "You cannot refer to values from the current row and use them in the new row".
In MySQL > 8.0.19 perhaps VALUES(ROW) can help. Or you can perhaps write you own UDF which does it.
You can't omit these columns from a REPLACE command, unless it is the default value for the column.
According to the documentation:
Any missing columns are set to their default values. [...] You cannot refer to values from the current row and use them in the new row.
It may be better to use a standard UPDATE command instead, which can reference the current column value.
Is it possible to have an INSERT statement return the columns affected into a SELECT statement?
For example, I have the statement:
INSERT INTO work_day (WorkDateId, TimeframeId) VALUES (#selecteddateid,#timeframeid);
But work_day has an auto incrementing, work_dayId, that gets created when this row data is inserted. I want to put this work_dayId in another statement, but I was wondering if it would be able to nest this INSERT inside a SELECT that will select the affected/created row.
So would I be able to place this statement like so:
INSERT INTO appointment
(customerid, WorkDayId, UserId, Priority, Assign)
VALUES
(#otherdata
(SELECT WorkDayId FROM work_day WHERE WorkDateId = (INSERT INTO work_day (WorkDateId, TimeframeId) VALUES (#selecteddateid,#timeframeid))));
AS #Gordon stated:
No, you cannot do that. You want last_insert_id()
Posting it here as an answer for better visibility.
I am trying to insert multiple rows into two tables connected by a foreign key that is autoincrement. I can't seem to find a good solution.
Tables:
eav_attribute_option
option_id (PK, Autoincrement)
attribute_id
sort_order
eav_attribute_option_value
value_id (PK, Autoincrement)
option_id (FK)
store_id
value
I want to do this:
insert into eav_attribute_option(attribute_id) values(100,101,102,103,...);
insert into eav_attribute_option_value(option_id,store_id,value) values
(1,0,"English"),(1,1,"German"),(2,0,"English1"),(2,1,"German2")
What would be the best approach to this, I can't seem to find a good one. :
Get next autoincrement then insert with it (need to lock table between)
Insert first part, then retreive PK values, build second part and insert (data incomplete for some time, what happens on error in second part?)
Some way to insert with join if it's possible?
Edit:
Just to clarify, I am looking to use the least amount of queries possible. I know I can do last inserted id, but I don't want to kill the server with thousands of inserts.
You can try something like this:
insert into eav_attribute_option (attribute_id) values(100);
insert into eav_attribute_option_value (option_id, store_id, value)
values (LAST_INSERT_ID(), 0, "English");
But you will need to insert the rows one by one. Consider doing a loop in your application.
$count = count('Count post value'); // $_POST value count
for($a=0;$a<$count;$a++)
{
$insert = 'insert into eav_attribute_option(attribute_id,sort_order) values (value1,value2)';
mysql_query($insert);
$insert_id = mysql_insert_id();
$insert2 = 'insert into eav_attribute_option_value(option_id,store_id,value) values
($insert_id,0,"English")';
mysql_query($insert2);
}
I have three tables in my database. A users table, StoreA and StoreB
StoreA and StoreB both have a unique key which is the user ID value.
What I want is; When I create a user and insert them into the database, how can I Insert a row into the other two tables without too many additional queries.
I figure I can do this by inserting the user in one query,
then in another return the newly created user ID,
then in another, using said ID, create rows in StoreA and StoreB
Can I cut out the middle query?
Can I cut out the middle query?
YES
START TRANSACTION;
INSERT INTO user (id, name, other)
VALUES (null, 'John','rest of data');
INSERT INTO storeA (id, user_id, other)
VALUES (null, #user_id:= LAST_INSERT_ID(), 'rest of data');
INSERT INTO storeB (id, user_id, other)
VALUES (null, #user_id, 'rest of data');
COMMIT;
See: http://dev.mysql.com/doc/refman/5.0/en/getting-unique-id.html
It's a good idea to do this in a transaction, you you're not stuck with just a user with no other data if something goes wrong.
It's not a DB requirement though.
Yes - there should be a function available to get the last inserted ID (assuming it's an autoincrement field) without another query. In PHP, it's mysql_insert_id(). Just call that after the first query.
YES
Q1: insert into table1 values (...);
Q2: insert into table2 values (last_insert_id(), ...);
last_insert_id is the default mysql build-in function
Most of the mysql libraries in various programming language did support return last insert id.
But You did not mention what sort of language you are using to connect to mysql.,
so cannot provide any example
I just wanted to share a php solution.
If you're using mysqli, first execute your insert query.
Then do
$db_id = $this->db->insert_id;
Why don't you use their username as the primary key instead of creating an arbitrary user_id field thats auto incremented? Their user names are unique, right?
If I insert multiple records with a loop that executes a single record insert, the last insert id returned is, as expected, the last one. But if I do a multiple records insert statement:
INSERT INTO people (name,age)
VALUES ('William',25), ('Bart',15), ('Mary',12);
Let's say the three above are the first records inserted in the table. After the insert statement I expected the last insert id to return 3, but it returned 1. The first insert id for the statement in question.
So can someone please confirm if this is the normal behavior of LAST_INSERT_ID() in the context of multiple records INSERT statements. So I can base my code on it.
Yes. This behavior of last_insert_id() is documented in the MySQL docs:
Important
If you insert multiple rows using a single INSERT statement, LAST_INSERT_ID() returns the value generated for the first inserted row only. The reason for this is to make it possible to reproduce easily the same INSERT statement against some other server.
This behavior is mentioned on the man page for MySQL. It's in the comments but is not challenged, so I'm guessing it's the expected behavior.
I think it's possible if your table has unique autoincrement column (ID) and you don't require them to be returned by mysql itself. I would cost you 3 more DB requests and some processing. It would require these steps:
Get "Before MAX(ID)" right before your insert:
SELECT MAX(id) AS before_max_id FROM table_name`
Make multiple INSERT ... VALUES () query with your data and keep them:
INSERT INTO table_name
(col1, col2)
VALUES
("value1-1" , "value1-2"),
("value2-1" , "value2-2"),
("value3-1" , "value3-2"),
ON DUPLICATE KEY UPDATE
Get "After MAX(ID)" right after your insert:
SELECT MAX(id) AS after_max_id FROM table_name`
Get records with IDs between "Before MAX(ID)" and "After MAX(ID)" including:
SELECT * FROM table_name WHERE id>$before_max_id AND id<=$after_max_id`
Do a check of retrieved data with data you inserted to match them and remove any records that were not inserted by you. The remaining records have your IDs:
foreach ($after_collection as $after_item) {
foreach ($input_collection as $input_item) {
if ( $after_item->compare_content($input_item) ) {
$intersection_array[] = $after_item;
}
}
}
This is just how a common person would solve it in a real world, with parts of code. Thanks to autoincrement it should get smallest possible amount of records to check against, so they will not take lot of processing. This is not the final "copy & paste" code - eg. you have to create your own function compare_content() according you your needs.