i want to store auto increment id with string "SDMP" HOW TO DO THAT? when id increment it will be like SDMP1, SDMP2,....Like that
"Insert concat('SDMP', m_id) as id from merchant where m_id='" + id + "'";
I WANT TO SHOW DRIVER ID LIKE SDMP1 IN GRIDVIEW BUT I WANT ID IN SDMP1 FORMAT
If you want to update the existing table (where m_id is int and auto increment) then you can use this(before update query you need to change datatype of m_id)
ALTER TABLE merchant
MODIFY COLUMN id varchar(50);
then use update query
UPDATE merchant set m_id=CONCAT("SDMP",m_id);
OR
If you want to insert m_id as SDMP1, SDMP2 autoincrement then you can use this
Get Last ID
Get the INT part within the string
Increment the value
Concatenate
Save to DB
moreinfo
INSERT INTO merchant
SELECT CONCAT("SDMP",SUBSTRING(m_id,5)+1),"abc4"
FROM merchant order by m_id desc limit 1;
NOTE: if no row in the DB then manually insert SDMP1 as the first row in DB
OR
Keep thing simple, you keep m_id as int auto_increment in DB and while retrieving data from DB concat with SDMP CONCAT("SDMP",m_id)
and while searching in DB take integer part from gridview of m_id column
Related
I have a table Person with ID(Guid), FirstName(string), LastName(string) and 3000 entries. What I desperately need is the rank of a certain entry by ID in a sorted query by FirstName and LastName.
So for example: I search for any entries with FirstName or LastName containing the String 'mil' which returns 62 entries sorted. Since I know the ID of an entry somewhere in this result, I need the row_index of this entry.
I tried this with a Temp Table before, but since I'm working with sqlite-pcl for UWP I can't use 'CREATE TEMP TABLE' statements and so on, thus I need a solution in a single query.
PRAGMA temp_store = MEMORY;
DROP TABLE IF EXISTS TempQuery;
CREATE TEMP TABLE TempQuery AS SELECT ID FROM Person WHERE (Firstname LIKE '%mil%' OR LastName LIKE '%%');
SELECT rowid FROM TempQuery WHERE ID = '48a0231a-af41-450d-a291-5912d39119c9' LIMIT 1;
I want to create a table with a field that is unique and limited to a certain value. Lets say that the limit is 100, the table is full, I remove a random row, and when I create a new row it has the value that was freed before.
It doesn't need to be the fastest thing in the world (the limit is quite small), I just want to implement it in a DB.
Any ideas?
Create one more column in main table, say deleted (integer, 0 or 1). When you need to delete with certain id, do not really delete it, but simply update deleted to 1:
UPDATE mytable SET deleted=1 WHERE id = <id_to_delete>
When you need to insert, find id to be reused:
SELECT id FROM mytable WHERE deleted LIMIT 1
If this query returns empty result, then use INSERT to create new id. Otherwise, simply update your row:
UPDATE mytable SET deleted=0, name='blah', ... WHERE id=<id_to_reuse>
All queries reading from your main table should have WHERE constraint with NOT deleted condition:
SELECT * FROM mytable WHERE NOT deleted
If you add index on deleted, this method should work fast even for large number of rows.
This solution does everything in a trigger, so you can just use a normal INSERT.
For the table itself, we use an autoincrementing ID column:
CREATE TABLE MyTable(ID INTEGER PRIMARY KEY, Name);
We need another table to store an ID temporarily:
CREATE TABLE moriturus(ID INTEGER PRIMARY KEY);
And the trigger:
CREATE TRIGGER MyTable_DeleteAndReorder
AFTER INSERT ON MyTable
FOR EACH ROW
WHEN (SELECT COUNT(*) FROM MyTable) > 100
BEGIN
-- first, select a random record to be deleted, and save its ID
DELETE FROM moriturus;
INSERT INTO moriturus
SELECT ID FROM MyTable
WHERE ID <> NEW.ID
ORDER BY random()
LIMIT 1;
-- then actually delete it
DELETE FROM MyTable
WHERE ID = (SELECT ID
FROM moriturus);
-- then change the just inserted record to have that ID
UPDATE MyTable
SET ID = (SELECT ID
FROM moriturus)
WHERE ID = NEW.ID;
END;
sql has a Table called emp.
emp(emp_id int IDENTITY primary key, EmployeeName varchar(50),.......)
I want to Insert a record to above table. Here is my code in asp.net.
DBconnection dbcon = new DBconnection();
string query = "insert into emp values('" + TextBox_EmpName.Text + "','" + ....);
int no1 = dbcon.insertQuery(query);
I have another table called emp-relation
emp-relation(emp_id int primary key, count int, ....)
-- foreign key (emp_id)references emp(emp_id)
My problem is when I inserting the emp row ,I dont know what is the emp_id since it created by auto. And when I am going to insert to emp-relation , I want to get emp-id since it is the foreign key.
How can I do this? Is there any way to read last Insert row in Sql according to Time stamp or some thing? I believe that records are not sorted according to inserted timestamp in nature. please help me.
There's bascally two ways. The first way is to return the new ID from the first insert query:
insert into emp values(...)
select scope_identity() as NewID
The second way is to lookup the first row when you insert into the relation table:
insert emp-relation
(emp_idm, ...)
select emp_id
, ...
from emp
where emp_name = #EmpName
You have to pass in enough columns to make the reference unique.
I am using asp.net2008 and MY SQL.
I want to auto-generate the value for the field username with the format as
"SISI001", "SISI002",
etc. in SQL whenever the new record is going to inserted.
How can i do it?
What can be the SQL query ?
Thanks.
Add a column with auto increment integer data type
Then get the maximum value of that column in the table using "Max()" function and assign the value to a integer variable (let the variable be 'x').
After that
string userid = "SISI";
x=x+1;
string count = new string('0',6-x.ToString().length);
userid=userid+count+x.ToString();
Use userid as your username
Hope It Helps. Good Luck.
PLAN A>
You need to keep a table (keys) that contains the last numeric ID generated for various entities. This case the entity is "user". So the table will contain two cols viz. entity varchar(100) and lastid int.
You can then have a function written that will receive the entity name and return the incremented ID. Use this ID concatenated with the string component "SISI" to be passed to MySQL for insertion to the database.
Following is the MySQL Table tblkeys:
CREATE TABLE `tblkeys` (
`entity` varchar(100) NOT NULL,
`lastid` int(11) NOT NULL,
PRIMARY KEY (`entity`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
The MySQL Function:
DELIMITER $$
CREATE FUNCTION `getkey`( ps_entity VARCHAR(100)) RETURNS INT(11)
BEGIN
DECLARE ll_lastid INT;
UPDATE tblkeys SET lastid = lastid+1 WHERE tblkeys.entity = ps_entity;
SELECT tblkeys.lastid INTO ll_lastid FROM tblkeys WHERE tblkeys.entity = ps_entity;
RETURN ll_lastid;
END$$
DELIMITER ;
The sample function call:
SELECT getkey('user')
Sample Insert command:
insert into users(username, password) values ('SISI'+getkey('user'), '$password')
Plan B>
This way the ID will be a bit larger but will not require any extra table. Use the following SQL to get a new unique ID:
SELECT ROUND(NOW() + 0)
You can pass it as part of the insert command and concatenate it with the string component of "SISI".
I am not an asp.net developer but i can help you
You can do something like this...
create a sequence in your mysql database as-
CREATE SEQUENCE "Database_name"."SEQUENCE1" MINVALUE 1 MAXVALUE 9999999999999999999999999999 INCREMENT BY 001 START WITH 21 CACHE 20 NOORDER NOCYCLE ;
and then while inserting use this query-----
insert into testing (userName) values(concat('SISI', sequence1.nextval))
may it help you in your doubt...
Try this:
CREATE TABLE Users (
IDs int NOT NULL IDENTITY (1, 1),
USERNAME AS 'SISI' + RIGHT('000000000' + CAST(IDs as varchar(10)), 4), --//getting uniqueness of IDs field
Address varchar(150)
)
(not tested)
I've just thought about best way to store comments in database with appropriate numbers according to the article.
The idea is to store comments with composite primary key (commentId, articleId) where commentId is generated according to the given articleId. The system of generating should has same principle as IDENTITY generated columns in SQL Server, because if someone delete the comment, the number will be never used again. I guess there is not any functionality in Microsoft SQL Server to do that with composite PK, so I am asking about some replacement for this solution.
First thought was to use transaction to get MAX(commentId) + 1, but I am looking for something more abstract (maybe INSTEAD OF trigger), something that could be used for example in LINQ with no knowledge of the background, just insert to the appropriate table all required values (so no commentId) and save it.
I would use an autogenerated identity column for the commentId and have it be the primary key alone. I'd create an index on the articleId for look ups. I would also have createdDate column that is autopopulated with the current date on insertion -- mark it as db generated and readonly in LINQ so it doesn't require or try to insert/update the value. To get a numbering -- if showing them by date isn't enough -- I'd order by createdDate inversed and assign a numeric value in the select using Row_Number() or a numbering on the client side.
I would use an identity column as the key for the comments, why do you need a numbering for the comments stored in the database?
Thank you for responses, I wanted something with numbered comments because of referencing in the text of comments. I did not want to make reaction by names, sometimes one person reacts more times, so with this system, I will know to which one the person is replying.
So today I made up this INSTEAD OF INSERT trigger:
CREATE TRIGGER InsertComments ON Comments
INSTEAD OF INSERT
AS
DECLARE #Inserted TABLE
(
ArticleId INT NOT NULL,
UserId INT NOT NULL,
CommentDate DATETIME NOT NULL,
Content NVARCHAR(1000) NOT NULL,
RowNumber INT NOT NULL
)
INSERT INTO #Inserted
SELECT ArticleId, UserId, CommentDate, Content, ROW_NUMBER() OVER (ORDER BY CommentDate) AS RowNumber
FROM INSERTED
DECLARE #NumberOfRows INT = (SELECT COUNT(*) FROM #Inserted)
DECLARE #i INT = 1
WHILE (#i <= #NumberOfRows)
BEGIN
SET TRANSACTION ISOLATION LEVEL SERIALIZABLE
BEGIN TRAN
DECLARE #CommentId INT = (SELECT ISNULL(MAX(CommentId), 0)
FROM Comments WHERE ArticleId = (SELECT ArticleId
FROM #Inserted WHERE RowNumber = #i)) + 1
INSERT INTO Comments(CommentId, ArticleId, UserId, CommentDate, Content)
SELECT #CommentId, ArticleId, UserId, CommentDate, Content
FROM #Inserted WHERE RowNumber = #i
COMMIT
SET #i = #i + 1
END
I know this is not the perfect solution, but it works exactly how I needed. If any of you has some comments, I'll be happy to read them.