Using PHP I dynamically generate multiple values and insert them into a table, simplified example of an insert with some values:
INSERT INTO table (time1,time2)
VALUES ('08:00','09:00'),('09:00','10:00'),('11:00','12:00');
With the above example, I'd like to prevent this from inserting:
INSERT INTO table (time1,time2)
VALUES ('08:15','08:45'),('09:30','12:00');
Is it possible to make a range comparison between 2 columns when inserting multiple values? Or would I need to make a loop with single inserts (which I'd like to avoid for performance reasons)?
EDIT: I'm submitting the data by form with PHP. I guess the logical step is to use $_POST values and do a SELECT checking if the times conflict. Whether to use BETWEEN in SELECT or return all values back for a PHP function is another matter.
Check for indivisual entries form php, use this query to check the number of conflicts the new entry is making:
SELECT count(*) as `conflicts`
FROM table
WHERE
'08:15' BETWEEN time1 AND time2 -- user your variable here
OR
'08:45' BETWEEN time1 AND time2 -- user your variable here
Related
If i have insert query for example:
INSERT INTO user(username) VALUES('admin');
And then get the id of the inserted record with
LAST_INSERT_ID();
Looks find but what happens if between the insert and LAST_INSERT_ID() another insert is executed.
How MySQL knows to return the correct id (for the first or second insert) since no parameter is passed to LAST_INSERT_ID();
Is it save to use this function?
Thanks
I'm supposing that you mean what happen if i'm connected to the MySQL server and executing an INSERT but others are also doing insert, like updating a table on a website while client are currently using it.
If you go take a look at the documentation https://dev.mysql.com/doc/refman/8.0/en/information-functions.html there is a point that answers your questions:
The ID that was generated is maintained in the server on a
per-connection basis. This means that the value returned by the
function to a given client is the first AUTO_INCREMENT value generated
for most recent statement affecting an AUTO_INCREMENT column by that
client. This value cannot be affected by other clients, even if they
generate AUTO_INCREMENT values of their own. This behavior ensures
that each client can retrieve its own ID without concern for the
activity of other clients, and without the need for locks or
transactions.
This should be the same in MariaDB.
As discussed in the comment, you are wondering if you can use this in a php PDO environment. If you mean to use this directly from the database, it's a no, you won't be able to have the last inserted ID because you won't have the same client connection as PDO. If you want to use it directly from PDO please use the specific PDO function: http://php.net/manual/fr/pdo.lastinsertid.php , this should allow to do what you want.
If you insert multiple rows into a table using a single INSERT query, the LAST_INSERT_ID function returns the last insert id of the first row.
i.e
If your table id has 3 as column value and you will insert 4 rows in a single query then LAST_INSERT_ID will give you 4 instead of 7
If you insert 4 rows in 4 different insert query then LAST_INSERT_ID will give you 7
last_insert_id( ) Or mysqli_insert_id( ) will always return the id of last or most recent query. And also be noted that id field must have AUTO_INCREMENT enabled.
It doesn't give you the freedom to choose any specific table. Or you can't have id which is generated from your previous query.
So, from this point it serves a very small purpose. Only the last id, it doesn't matter which table.
To get last id from any specific table this query would be helpful : "SELECT id FROM table_name ORDER BY id DESC LIMIT 1"
I want to insert multiple rows into a table, using a single INSERT statement. This is no problem, since SQL offers the option to provide multiple rows as parameter for a single INSERT statement. Now, those rows contain an ID field that is incremented automatically, i.e. its value is set by the database, not by my code.
As a result, I would like to get the ID values of the inserted rows. My basic question is: How do I do that for MariaDB / MySQL?
As it turns out, this is pretty simple, e.g. in PostgreSQL, as PostgreSQL has the RETURNING clause for INSERT which returns the desired values for one or even for multiple rows. This is exactly what I want and it works.
Unfortunately, neither MariaDB nor MySQL have PostgreSQL's RETURNING clause, so I need to fallback to something such as LAST_INSERT_ID(), but this only returns the ID of the single last inserted row, even if multiple rows were inserted using a single INSERT. How do I get all the ID values?
My code currently looks like this:
INSERT INTO mytable
(foo, bar)
VALUES
('fooA', 'barA'),
('fooB', 'barB');
SELECT LAST_INSERT_ID() AS id;
How can I solve this issue in a way that works even with concurrent writes?
(And no, it's not an option to change to a UUID field, or something like this; the auto-increment field is given, and can not be changed.)
MySQL & MariaDB have the LAST_INSERT_ID() function, and it returns the id generated by the most recent INSERT statement in your current session.
But when your INSERT statement inserts multiple rows, LAST_INSERT_ID() returns the first id in the set generated.
In such a batch of multiple rows, you can rely on the subsequent id's being consecutive. The MySQL JDBC driver depends on this, for example.
If the rows you insert include a mix of NULL and non-NULL values for the id column, you have a risk of messing up this assumption. The JDBC driver returns the wrong values for the set of generated id's.
As stated in the comments, you can capture the inserted IDs (SQL Server):
use tempdb
create table test (
id int identity(1,1) primary key,
t varchar(10) null
)
create table ids (
i int not null
)
insert test(t)
output inserted.id into ids
values (null), (null), (null)
select *
from test
select *
from ids
I have a mysql table with several columns. on some conditions I run a script that duplicates the row.
This is done via these steps:
select all columns from the row to be duplicated
on the resulting array change two values out of 30 (new info are built on the fly using php scripts and are unique for the row). these values can be created any time during the update process
insert the new row with the usual insert into... that make me list again all the 30 fields and values
My question is: is there a way to change this script into:
create the new values
run a single query that will duplicate the row and at the same time update the values while duplicating?
So that i don't need to manipulate the array in php and I run just one query instead of two?
You can do it with a single query, but you will need to list all the fields:
INSERT INTO your_table
SELECT
NULL, #in place of auto-increment column (if any)
'some value for the field you want to change',
'some value for another field you want to change',
not_changed_field1,
not_changed_field2,
...
FROM your_table
WHERE <row has to be duplicated>
Just wanted to runt this by someone who knows more MySQL than myself
I perform a MySQL insert where I insert say 10 rows in one query. Then when you get MySQL's last insert id, it gives you the ID of the first inserted ID.
Is it safe to assume that the other IDs are consecutively the insert_id - insert_id+9? or is there any possible way this could not turn out to be the case?
Thanks
Yes, there is a possibility this will not always be the case.
With innodb_autoinc_lock_mode = 2, the rows inserted by a single INSERT statement can be assigned AUTO_INCREMENT values that are not consecutive (when concurrent INSERT statements are running.)
http://dev.mysql.com/doc/refman/5.1/en/innodb-auto-increment-handling.html
Been searching on Google for a while now without finding the answer to my problem. I have like 10 tables where 5 of them contains 150 rows. I want to add 15 rows to these 5 tables, is there any simple solution for this? I know it's easy to add the rows manually but I want to know anyway. What I'm looking for is something like this:
INSERT INTO all_tables VALUES (col1, col2, col3) WHERE row_number() = '150'
Is it possible? Thanks in advance!
You can only target updates to one table at a time, which must always be specified by name. Also, you cannot specify a WHERE clause on an INSERT. Your best bet is probably to write one INSERT and copy and paste for the rest.
You could:
Loop through a list of the relevant table names.
Run a dynamic query like select count(*) into #c1 from SpecifiedTable against the relevant table, returning the count into a declared variable.
If the returned value is 150, run another dynamic query to insert the relevant values into the specified table.
You can find out more about dynamic queries and returning values from them in MySQL here. If this is a once-off, you will probably find it easier to do it manually.