MYSQL :: Re-arrange Primary Key Sequence

Primary Key Field: Varchar(32) Versus Sequence
I got in the habit of coding primary key fields as varchar(32) that was generated by an md5() since it was a public site and I wanted to avoid people guessing record numbers (for other reasons).

Is there a performance problem with doing that?

If so, how do you tackle the same concern?

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Cost Of Single Primary Key VS Multiple Primary Key
Could someone advise me on difference between the cost of using a single primary key and multiple primary key? Especially on their effect on joins? For example, with the following table:

---+-----+-------+-----
ID | Name| Class | Test
---+-----+-------+-----

is it more cost effective to use a single unique primary key (ID) or use a multiple primary key pair (Name + Class + Test)

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Disrupted Sequence
Another brainteaser:

CREATE TABLE IF NOT EXISTS `test` (
`id` INT(11) unsigned NOT NULL auto_increment,
`cid` VARCHAR(10) NOT NULL,
`item` VARCHAR(10) NOT NULL,
`val` INT(11) NOT NULL,
`dt` datetime NOT NULL default '0000-00-00 00:00:00',
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1

In the above example table I need to find the first 5 highest values of val that break the sequential set of values. In other words: say I have values 49,48,45,44,43,40,39,37,36,34 of val in my table, with 49 being the highest value of val (need to sorted first, because values may randomly be dispersed in my table), then I want to get 47,46,42,41,38 as the query result.

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Create A Sequence?
I am creating an application that will contain three tables that need to share the same sequence. Upon digging through the docs, I do not see how I could do this.

Could someone give me some guidance into this?

Also, As I read the docs, when I am creating tables, there is something about an InnoDB? Sorry to be confused, but I am not sure how to begin creating my database, nor tables without this knowledge.

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Sequence Substitute
I have a problem about create sequence number which can be reset after MAXVALUE has been assigned. In the older version of mysql i can use "create sequence", but in the recent version i can't do that anymore. All i know in mysql ver 5 is "Auto_increment" which cannot be reset number without delete or truncate table.

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CREATE SEQUENCE ?
Tracing some examples in a book from Apress,
for some reason they go for Oracle in this book -
not my cup of tea, especially not when I am sitting on
a vista-terminal. Enough of my complaing.

How do I create a sequence in mysql ?

This is the example I am stuck with:

CREATE SEQUENCE SEQ_ID_GEN INCREMENT BY 1 START WITH 100 MINVALUE 1 CACHE 50 ;

How do I write that sentence in mysql ?

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Sequence Creation
I am not able to create a sequence in MySql.. But its giving error.

Can any one pls tell me how can i do that?

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Sequence Generation
I was wondering if there was something close to CREATE SEQUENCE in MaxDB for standard MySQL.

I'm thinking of just doing a table/stored procedure and calling it a day, but was wondering if MySQL had some other alternative.

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What Collation Sequence?
I've just transferred a small PHP/MySQL application from a Firepages phpdev5 install to an XAMPP install, so I've got new versions of everything. I used phpMyAdmin to export and import the tables of the database. When recreating the database on my new install I selected the default collation (latin1_general_ci) but my application is now displaying ? in place of a number of characters so I guess I got it wrong. I can't see where in the old phpMyAdmin (2.3.0-rc3) to determine what collation the database uses.

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Identity, Sequence, Serial
Does MySQL offer capability for any of the following?
- IDENTITY
- SEQUENCE
- SERIAL
Or is AUTO_INCREMENT the catch-all for the functionality of all of the above? I ask because I'm looking into Java EJB3 which describes support for any of the above (as well as AUTO_INCREMENT, so I'm not out of luck completely).

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Selcting Date Sequence
I am trying to return a set or rows that represent all of the days between two dates. For example, I want to select all the days between December 25th, 2005 and January 5th of 2006, and i am looking for it to return (shown here in CSV)
2005,12,25
2005,12,26
2005,12,27
2005,12,28
2005,12,29
2005,12,30
2005,12,31
2006,01,01
2006,01,02
2006,01,03
2006,01,04
2006,01,05

So, for any date, i want to select all the days in between. Any ideas?

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ALPHANUMERIC SEQUENCE IN 5.0 VERSION?
IS MYSQL5.0 SUPPORT SEQUENCE?

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How To Create A Sequence In MySQL
I am not able to create a sequence in MYSQL 5.0
Want help on creating the same.

Basically, what I am looking for is, that I should get a number greater that the last one on every call to this sequence.

In Oracle, one can simply write something like:-
CREATE SEQUENCE seq_ordermaster
increment by 1 start with 1
maxvalue 999999minvalue 1
nocache
Nocycle;
And while calling, one can use it by selecting seq_ordermaster.nextval from DUAL

Considering the fact that there is no DUAL table in MySQL, how can One write such a sequence and also, how one can get the next value on each select statement?

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Mysql Execution Sequence
I need to retrieve the last value from a column in a mysql table, perform some actions on it, then add 1 to the original value and store a new entry.

I am worried that if multiple users access the database at the same time I will end up with duplicated 'new values'. Does mysql complete execution of a script before it allows access to another user or do I need to 'lock' the table in some way while the script executes?

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Find The Number Of A Row In A Sequence
MySQL Code:
SELECT * FROM comments WHERE id=12345 ORDER BY rating

Is there a way to determine the position that this rows appears in the sequence?

Eg, so I can print out:

"This site is rated position x out of y"

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Bulk Insert Of New Records In Sequence
I am looking to create a querty that searches for the max value a field
called listnum in a table called tbl_listing and then interests 25 new
records with listnum's starting 1 higher then the max value.

ie if the highest listnum is 1000 it should insert new records with a
listnum of 1001-1024. All the other fields in the table can be blank.

Is there a simple (or not so simple) query that I can run to do this?

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How To Generate Sequence Values During Query
I have query like below:

SELECT part_no,part_nm,qty FROM tb_stok_out ORDER BY part_no

as result:

part_no part_nm qty

aaa asdfd 3
abab sdfsdf 4
abab adfdf 5

Is it possible in mysql to generate sequence number using query, so the result will be like below :

1 aaa asdfd 3
2 abab sdfsdf 4
3 abab adfdf 5
... etc

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Change The Sequence Of Column In Table
I am using MySql Query Browser I want to change the Sequence of Column in data table
e.g.

Before : table sequence is (UserID, Name, BOD)
After : table sequence is (User ID, BOD, Name)

How can I do that?

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Create Sequence Syntex Errors Out
I installed mysql 5 and trying to setup database. Somehow it can't create sequence. it throws generic 'check the manual that corresponds to your mysql server version......'.

I have tried just about anything nothing works.
Also tried to reinstall mysql few times--same thing.
Also tried to go through mysql 5 manual nothing is in there for sequence.
Or sequence is not supported with mysql version i have?

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Inserting New Data Within A Structured Sequence
I'm trying to organize rows in a specific sequence. However, I also want the capability to insert new rows within that sequence and not simply append them to the end of the dataset as autosequencing would have you do. How is this accomplished?

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Extract Data According To Preset Sequence... How?
wondering whether i can make this work...

first, i will make an array like this:

Quote:

$category_id[]="10,6,9,8,3";

then i wanna extract the information( category name, category id, and sub category into array and arrange them in the preset sequence in category_id[] above.

Quote:

$query="select * from category order by $category_id[] ";
$result="mysql_query($query) or die(mysql_error());

while ($row=mysql_fetch_assoc($result))
{
echo $row['category_id'];
echo $row['category_name'];
echo $row['subcategory'];
}

the output i wish to get is like this:

Quote:

1st result:
category id: 10
category name= the name of category 10
sub category=
sub 1 category 10
sub 2 category 10
sub 3 category 10

2nd result:
category id: 6
category name= the name of category 6
sub category=
sub 1 category 6
sub 2 category 6
sub 3 category 6

3rd result:
category id: 9
category name= the name of category 9
sub category=
sub 1 category 9
sub 2 category 9
sub 3 category 9

I'm confuse in the extraction info according to the preset sequence... can anyone please share some ideas? will this idea works?

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Max Sequence Number In Claim Transaction Table
have a table that contains a transactional history showing how a claim amount has changed over time. Each time the claim amount is updated, a new claim sequence number is used.

The fields I have are Claim Number(CLMKYT), Claim Sequence(CLMSQT), Claim Amount(Â£)(OUTSTT) and Date the claim was entered/updated (EFFDTT)

I want to pull out the latest (most recent) claim amount for each claim as at any particular date.

I have the below query which I think almost gets me there, but not quite!

Code: .....

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Generated Sequence # Based Upon Content Of Row Being Inserted
I have a table -

CREATE TABLE `sample` (
`Id` smallint(6) NOT NULL auto_increment,
`division` varchar(5) NOT NULL,
`secion` varchar(5) NOT NULL,
`div_sect_seq` smallint(6) NOT NULL default '1',
PRIMARY KEY (`Id`)
);

I'd like to write the insert statement that would generate the next div_sect_seq number based upon the value being inserted into the table.

Let's say that the table contains:

|--id--|-division-|-section-|-div_sect_seq-|
| 1 | SC | XX | 000001 |
| 2 | SC | YY | 000001 |
| 3 | SC | XX | 000002 |

I'd like to insert a row for divsion = 'SC' and section = 'XX' with the next div_sect_seq (which would be the max value of div_sec_seq + 1 on the sample table for the division and section) which should be the value of 000003.

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Ordering By Sequence Field With Empty Values
I have a sequence field in my db table that I'm using to order a list. I'm trying to ORDER BY this field, but it puts the empty values before 1 such as
empty, empty, 1, 2, 3, 4
instead of
1, 2, 3, 4, empty, empty, empty
How can I fix this?

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Index On Long Column And Auto Sequence In Mysql
How do we create index on long columns in Mysql? we want to store the timestamp component of the data field in a long data type and be able to index on it.

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MySQL Variables, Modifying Microsoft SQL Sequence Insert For Use In Mysql
I have the following microsoft SQL statement that inserts 25 new
records in sequence. However I am trying to modify this to work in
MySQL.

I cant seem to get the variable decleration right. I tried using
DECLARE CurVal int but that generates a mysql error. How can I modify
the code below to work under mysql? Code:

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Ordering In Queries By Sequence Of Elements In "IN"
I need a query which delivers results in the order I have in the element sequence after "IN".

SELECT aid, cid, vid FROM table WHERE aid IN (5,7,3)

I want to see the resuts of the query submitted in the same order, it means the first row should be with aid 5, the second with aid 7 and the third with 3.

Without "ORDER BY" I get the results in sequence 3, 5, 7.

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ORDER BY :: Sequence Order
Is it possible to ORDER BY based on the sequence order, for instance I use this Query:

SELECT * FROM Showroom WHERE Artnumber IN (52900, 52536, 52730)

the result is this:

Artnumber Price
52536 25,80
52730 1,90
52900 31,10

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0 As A Primary Key Value
I want agentid to be 0 for the record "UNASSIGNED," but every time I update
the table it gets set to the next autoincrement value.

This is my primary key:
agentid int(11) unsigned PRI NULL auto_increment

I could rewrite my scripts to not use the 0 value from the database, but
that would take some time.

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Primary Key ID
I was wondering is there any different speed if I don't add the column "ID" as primary key into table where I never use it to do mysql query like (select * where id=10000) so do I really need a column "ID"?
I have over 10 thousand of entries but my program does not touch any ID column.
I've seen some programs use ID but they don't use it. What the purpose of having ID? will it speed up faster even if you don't use mysql query

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Except Primary Key
Is there a good way to SELECT all the columns in a table except for the PRIMARY KEY?

For example: SELECT * FROM tbl WHERE * != PRIMARY KEY
(obviously this is poor syntax, but I think it gets the point across)
Maybe there's a way to do this with a subquery? I'm not really sure how to isolate the primary key.

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Getting Primary Key
.I have 2 tables:

Table 1:
refid int auto_increment
name text
table2_refid int

Table 2:
refid int auto_increment
name text
table1_refid int

I need to insert a PHP form registration directly into 2 separate tables.

Currently what i am doing is to:
Insert into Table1;
Select refid from Table1;
Insert into Table2;
Select refid from Table2;
Update Table1 set table2_refid;

I do believe that there is some functions in mysql that can help me cut short this process of updating or retrieving the last auto_increment figure. But I do not know what is it, can anyone please advise a quicker way of achieving the same end result?.

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Primary Key Name
I would like to know primary key can explicitely be named in mysql ?

The following is how primary key can explicitely be named in oracle.

create table myTable (
a number,
b number,
c number,
constraint pk_name primary key (a, b))

In mySQL, I define primary key name as 'pkey_name'

ALTER TABLE myTable ADD CONSTRAINT `PKEY_NAME` PRIMARY KEY (A,B);

But primary key name is still 'PRIMARY' , not 'PKEY_NAME';

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How To Name A Primary Key
How should i give a name to primary key

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Primary Key?
I have a table with the following fields.

Streetname
houseno
aptno
owner
homephone
workphone
zip

I want to be able to create a primary key using a combination of fields (streetname, houseno, and aptno) is that possible and how would I do that using phpmyadmin?

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Int(11) Vs Int(32) As Primary Key
I know that these two have the same value range, but performance wise(joining tables), is there any difference?

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URL As Primary Key?
What are the performance implications of the primary key field of a MySQL table being a web page URL? Obviously each one will be unique, but may be fairly lengthy. Should I avoid this or will it not be an issue?

I would estimate that at any one time, the table itself would contain roughly 500,000 records.

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Order By Primary Key
I'm building an Ajax table which fetches its contents from mySQL. The
idea is that the table displays x results on each page, and when you
click 'next page' it downloads the next x results and displays them.

The table uses an arbitrary SQL string to fetch results, and I'm stuck
on how to access just a small result set. Since the SQL is arbitrary I
can't use WHERE myfield = somevalue, because I don't know what
'myfield' is.

I'd like to substitue 'myfield' for the primary key of whatever table
I'm accessing.

So "select * from table where myfield < x and myfield y" becomes
"select * from table where table_primary_key < x and table_primary_key

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Reset Primary
I have built a database with a Primary Key / Auto Increment.
I have been doing loads of testing with adding and deleting records.
Now I need to delete all of the test records, and put the database on a live
website.Is there anyway to reset the Primary Key back to 1. Now when I have deleted
all the records, the Primary Key uses the next number from when the records
existed.

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Indexs, Primary
I have a very small db of only like 15 files, and with 120 records.

If I do a query from the page, via a php file it seems to take 2-3 seconds
for the results to come up.

I'm anticipating having a lot more records, upwards of 300-800 records.

I'm looking for the best way to create my indexes for fast response times. I
think right now that the performance isn't that slow.

My primate key is presently set to ID which is an autoincremting field with
a length of 6.

I do have queries that call for records that match a state also.

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Indexs, Primary And Such
I have a very small db of only like 15 files, and with 120 records.

If I do a query from the page, via a php file it seems to take 2-3 seconds
for the results to come up.
I'm anticipating having a lot more records, upwards of 300-800 records.

I'm looking for the best way to create my indexes for fast response times. I
think right now that the performance isn't that slow.

My primate key is presently set to ID which is an autoincremting field with
a length of 6.

I do have queries that call for records that match a state also.

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Finding Primary Key
I have a mysql db with with autoincrementing primary keys in each table. I
want to allow a user to add a record using a php webpage. Once the page is
added how can I re SELECT that record (for the user to verify) if I don't
know what the primary key was when it was inserted?
Is the only way to not use autoincrement and choose the primary key value
myself?

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Foreign Key And Primary Key
I'd like to create a table with PRIMARY KEY k (a,b,c) where a, b, c are foreign key. Is it possible? How can I do?

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Primary Key == Index
when I create a table, I always make the first column my unique-id, and make
this primary key auto-increment.
Does this mean that the table will be indexed by mysql on this key - or do I
need to explicitly do this too?
e.g.

create table note
(
note_id INTEGER(9) AUTO_INCREMENT PRIMARY KEY,
mytext varchar(255)
);

So do I need to add something to get mysql indexing on the primary key?

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(primary Key == Index) ?
when I create a table, I always make the first column my unique-id, and make
this primary key auto-increment.

Does this mean that the table will be indexed by mysql on this key - or do I
need to explicitly do this too? e.g.

create table note
(
note_id INTEGER(9) AUTO_INCREMENT PRIMARY KEY,
mytext varchar(255)
);

So do I need to add something to get mysql indexing on the primary key?

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128 Bit Values As Primary Key
Suppose that 'bigkey' is a column capable of representing the value of
a 128-bit unsigned integer in some efficient fashion... maybe as a
CHAR or VARCHAR field big enough to hold its decimal or hex
representation, or maybe some other datatype, and ${128bitvalue} is a
representation of it acceptable to MySQL.

Suppose 'smallkey' is an UNSIGNED INTEGER column.

Which of the following two queries is likely to be faster and more
efficient?

SELECT somecolumn, anothercolumn FROM foo, bar WHERE foo.bigkey =
${128bitvalue} AND bar.bigkey = ${128bitvalue}

SELECT somecolumn, anothercolumn FROM main, foo, bar WHERE main.bigkey
= ${128bitvalue} AND foo.smallkey = main.smallkey AND bar.smallkey =
main.smallkey

If MySQL had a native 128-bit integer type, it would probably be a
no-brainer to just use it directly. Unfortunately, as far as I know,
there's no way to store a 128-bit integer in a MySQL column without
converting it into some alternate representation first.

Assuming that I'm still better off using the 128 bit value's
representation directly as the key instead of joining it via a third
table, what's the most efficient way to represent that 128 bit value
to MySQL? CHAR(39)? VARCHAR(39)? Some other format?

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Primary Key Offset
I have a table that contains a smallint primary key that is auto
incremented. I would like to start this table's seed value at 1000. I
thought that I could do this...

ALTER TABLE `servers` CHANGE `server_id` `server_id` SMALLINT( 4 )
DEFAULT '1000' NOT NULL AUTO_INCREMENT

But that does not seem to work.

Could anyone shed some light on how I can change the start value of an
auto increment integer?

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