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how to prevent 0 in blank textbox event

I want to fetch data in texbox1 event and insert that fetched data into another table based on primary key search it doing perfectly like on primary key 8.
But when I want to enter new data like 9 primary key it adds 0 primary key on blank texbox1 how to prevent this

MySQL uses the AUTO_INCREMENT keyword to perform an auto-increment feature.
By default, the starting value for AUTO_INCREMENT is 1, and it will increment by 1 for each new record.
To let the AUTO_INCREMENT sequence start with another value, use the following SQL statement:
ALTER TABLE YourTable AUTO_INCREMENT=100;

How to Auto-increment non-integer primary key in sql-server? [duplicate]

Can I make a primary key like 'c0001, c0002' and for supplier 's0001, s0002' in one table?

The idea in database design, is to keep each data element separate. And each element has its own datatype, constraints and rules. That c0002 is not one field, but two. Same with XXXnnn or whatever. It is incorrect , and it will severely limit your ability to use the data, and use database features and facilities.
Break it up into two discrete data items:
column_1 CHAR(1)
column_2 INTEGER
Then set AUTOINCREMENT on column_2
And yes, your Primary Key can be (column_1, column_2), so you have not lost whatever meaning c0002 has for you.
Never place suppliers and customers (whatever "c" and "s" means) in the same table. If you do that, you will not have a database table, you will have a flat file. And various problems and limitations consequent to that.
That means, Normalise the data. You will end up with:
one table for Person or Organisation containing the common data (Name, Address...)
one table for Customer containing customer-specific data (CreditLimit...)
one table for Supplier containing supplier-specific data (PaymentTerms...)
no ambiguous or optional columns, therefore no Nulls
no limitations on use or SQL functions
.
And when you need to add columns, you do it only where it is required, without affecting all the other sues of the flat file. The scope of effect is limited to the scope of change.

My approach would be:
create an ID INT IDENTITY column and use that as your primary key (it's unique, narrow, static - perfect)
if you really need an ID with a letter or something, create a computed column based on that ID INT IDENTITY
Try something like this:
CREATE TABLE dbo.Demo(ID INT IDENTITY PRIMARY KEY,
IDwithChar AS 'C' + RIGHT('000000' + CAST(ID AS VARCHAR(10)), 6) PERSISTED
)
This table would contain ID values from 1, 2, 3, 4........ and the IDwithChar would be something like C000001, C000002, ....., C000042 and so forth.
With this, you have the best of both worlds:
a proper, perfectly suited primary key (and clustering key) on your table, ideally suited to be referenced from other tables
your character-based ID, properly defined, computed, always up to date.....

Yes, Actually these are two different questions,
1. Can we use varchar column as an auto increment column with unique values like roll numbers in a class
ANS: Yes, You can get it right by using below piece of code without specifying the value of ID and P_ID,
CREATE TABLE dbo.TestDemo
(ID INT IDENTITY(786,1) NOT NULL PRIMARY KEY CLUSTERED,
P_ID AS 'LFQ' + RIGHT('00000' + CAST(ID AS VARCHAR(5)), 5) PERSISTED,
Name varchar(50),
PhoneNumber varchar(50)
)
Two different increments in the same column,
ANS: No, you can't use this in one table.

I prefer artificial primary keys. Your requirements can also be implemented as unique index on a computed column:
CREATE TABLE [dbo].[AutoInc](
[ID] [int] IDENTITY(1,1) NOT NULL,
[Range] [varchar](50) NOT NULL,
[Descriptor] AS ([range]+CONVERT([varchar],[id],(0))) PERSISTED,
CONSTRAINT [PK_AutoInc] PRIMARY KEY ([ID] ASC)
)
GO
CREATE UNIQUE INDEX [UK_AutoInc] ON [dbo].[AutoInc]
(
[Descriptor] ASC
)
GO

Assigning domain meaning to the primary key is a practice that goes way, way back to the time when Cobol programmers and dinosaurs walked the earth together. The practice survives to this day most often in legacy inventory systems. It is mainly a way of eliminating one or more columns of data and embedding the data from the eliminated column(s) in the PK value.
If you want to store customer and supplier in the same table, just do it, and use an autoincrementing integer PK and add a column called ContactType or something similar, which can contain the values 'S' and 'C' or whatever. You do not need a composite primary key.
You can always concatenate these columns (PK and ContactType) on reports, e.g. C12345, S20000, (casting the integer to string) if you want to eliminate the column in order to save space (i.e. on the printed or displayed page), and everyone in your organization understands the convention that the first character of the entity id stands for the ContactType code.
This approach will leverage autoincrementing capabilities that are built into the database engine, simplify your PK and related code in the data layer, and make your program and database more robust.

First let us state that you can't do directly. If you try
create table dbo.t1 (
id varchar(10) identity,
);
the error message tells you which data types are supported directly.
Msg 2749, Level 16, State 2, Line 1
Die 'id'-Identitätsspalte muss vom
Datentyp 'int', 'bigint', 'smallint',
'tinyint' oder 'decimal' bzw.
'numeric' mit 0 Dezimalstellen sein
und darf keine NULL-Werte zulassen.
BTW: I tried to find this information in BOL or on MSDN and failed.
Now knowing that you can't do it the direct way, it is a good choice to follow #marc_s proposal using computed columns.

Instead of doing 'c0001, c0002' for customers and 's0001, s0002' for suppliers in one table, proceed in the following way:
Create one Auto-Increment field "id" of Data Type "int (10) unsigned".
Create another field "type" of Data Type "enum ('c', 's')" (where c=Customer, s=Supplier).
As "#PerformanceDBA" pointed out, you can then make the Primary Key Index for two fields "id" & "type", so that your requirement gets fulfilled with the correct methodology.

INSERT INTO Yourtable (yourvarcharID)
values('yourvarcharPrefix'+(
SELECT CAST((SELECT CAST((
SELECT Substring((
SELECT MAX(yourvarcharID) FROM [Yourtable ]),3,6)) AS int)+1)
AS VARCHAR(20))))
Here varchar column is prefixed with 'RX' then followed by 001, So I selected substring after that prefix of it and incremented the that number alone.

We can add Default Constraint Function with table definition to achieve this.
First create table -
create table temp_so (prikey varchar(100) primary key, name varchar(100))
go
Second create new User Defined Function -
create function dbo.fn_AutoIncrementPriKey_so ()
returns varchar(100)
as
begin
declare #prikey varchar(100)
set #prikey = (select top (1) left(prikey,2) + cast(cast(stuff(prikey,1,2,'') as int)+1 as varchar(100)) from temp_so order by prikey desc)
return isnull(#prikey, 'SB3000')
end
go
Third alter table definition to add default constraint -
alter table temp_so
add constraint df_temp_prikey
default dbo.[fn_AutoIncrementPriKey_so]() for prikey
go
Fourth insert new row into table without specifying value for primary column-
insert into temp_so (name) values ('Rohit')
go 4
Check out data in table now -
select * from temp_so
OUTPUT -
prikey name
SB3000 Rohit
SB3001 Rohit
SB3002 Rohit
SB3003 Rohit

you may try below code:
SET #variable1 = SUBSTR((SELECT id FROM user WHERE id = (SELECT MAX(id) FROM user)), 5, 7)+1;
SET #variable2 = CONCAT("LHPL", #variable1);
INSERT INTO `user`(`id`, `name`) VALUES (#variable2,"Jeet");
1st line to get last inserted Id by removing four character than increase one value and set to a variable1
2nd line to make complete id with four character prefix and assign to variable2
insert new value with generated new primary key = variable2
you should have minimum one data in this table to work above SQL

No. If you really need this, you will have to generate ID manually.

empID increment on Add emp [duplicate]

How do I auto increment the primary key in a SQL Server database table? I've had a look through the forum but can't see how to do this.
I've looked at the properties but can't see an option. I saw an answer where you go to the Identity specification property and set it to yes and set the Identity increment to 1, but that section is grayed out and I can't change the no to yes.
There must be a simple way to do this but I can't find it.

Make sure that the Key column's datatype is int and then setting identity manually, as image shows
Or just run this code
-- ID is the name of the [to be] identity column
ALTER TABLE [yourTable] DROP COLUMN ID
ALTER TABLE [yourTable] ADD ID INT IDENTITY(1,1)
the code will run, if ID is not the only column in the table
image reference fifo's

When you're creating the table, you can create an IDENTITY column as follows:
CREATE TABLE (
ID_column INT NOT NULL IDENTITY(1,1) PRIMARY KEY,
...
);
The IDENTITY property will auto-increment the column up from number 1. (Note that the data type of the column has to be an integer.) If you want to add this to an existing column, use an ALTER TABLE command.
Edit:
Tested a bit, and I can't find a way to change the Identity properties via the Column Properties window for various tables. I guess if you want to make a column an identity column, you HAVE to use an ALTER TABLE command.

You have to expand the Identity section to expose increment and seed.
Edit: I assumed that you'd have an integer datatype, not char(10). Which is reasonable I'd say and valid when I posted this answer

Expand your database, expand your table right click on your table and select design from dropdown.
Now go Column properties below of it scroll down and find Identity Specification, expand it and you will find Is Identity make it Yes. Now choose Identity Increment right below of it give the value you want to increment in it.

CREATE TABLE Persons (
Personid int IDENTITY(1,1) PRIMARY KEY,
LastName varchar(255) NOT NULL,
FirstName varchar(255),
Age int
);
The MS SQL Server uses the IDENTITY keyword to perform an auto-increment feature.
In the example above, the starting value for IDENTITY is 1, and it will increment by 1 for each new record.
Tip: To specify that the "Personid" column should start at value 10 and increment by 5, change it to IDENTITY(10,5).
To insert a new record into the "Persons" table, we will NOT have to specify a value for the "Personid" column (a unique value will be added automatically):

Perhaps I'm missing something but why doesn't this work with the SEQUENCE object? Is this not what you're looking for?
Example:
CREATE SCHEMA blah.
GO
CREATE SEQUENCE blah.blahsequence
START WITH 1
INCREMENT BY 1
NO CYCLE;
CREATE TABLE blah.de_blah_blah
(numbers bigint PRIMARY KEY NOT NULL
......etc
When referencing the squence in say an INSERT command just use:
NEXT VALUE FOR blah.blahsequence
More information and options for SEQUENCE

When you're using Data Type: int you can select the row which you want to get autoincremented and go to the column properties tag. There you can set the identity to 'yes'. The starting value for autoincrement can also be edited there. Hope I could help ;)

I had this issue where I had already created the table and could not change it without dropping the table so what I did was:
(Not sure when they implemented this but had it in SQL 2016)
Right click on the table in the Object Explorer:
Script Table as > DROP And CREATE To > New Query Editor Window
Then do the edit to the script said by Josien; scroll to the bottom where the CREATE TABLE is, find your Primary Key and append IDENTITY(1,1) to the end before the comma. Run script.
The DROP and CREATE script was also helpful for me because of this issue. (Which the generated script handles.)

You can use the keyword IDENTITY as the data type to the column along with PRIMARY KEY constraint when creating the table.
ex:
StudentNumber IDENTITY(1,1) PRIMARY KEY
In here the first '1' means the starting value and the second '1' is the incrementing value.

If the table is already populated it is not possible to change a column to IDENTITY column or convert it to non IDENTITY column. You would need to export all the data out then you can change column type to IDENTITY or vice versa and then import data back.
I know it is painful process but I believe there is no alternative except for using sequence as mentioned in this post.

Be carefull like if you want the ID elements to be contigius or not. As SQLSERVER ID can jump by 1000 .
Examle: before restart ID=11
after restart , you insert new row in the table, then the id will be 1012.

You could do the following: New Table Creation:
-- create new table with Column ID which is Primary Key and Auto Increment --
CREATE TABLE titles(
id INT NOT NULL IDENTITY(1,1) PRIMARY KEY, --Primary Key with Auto-Increment --
keyword VARCHAR(260),
status VARCHAR(10),
);
If you Table Already exists and need to make the changes to ID column to be auto-increment and Primary key, then see below:
ALTER TABLE table DROP COLUMN id; // drop the existing ID in the table
ALTER TABLE table ADD id int IDENTITY(1, 1) NOT NULL; // add new column ID with auto-increment
ALTER TABLE table ADD CONSTRAINT PK_ident_test PRIMARY KEY CLUSTERED (id); // make it primary key

improve query performance on SQL Server table contain 3.5 Million rows and growing

I have written one application in C# which is connected to sql server database express edition, from front end I populate the particular table in database every few second and insert approx 200~300 Rows in this table.
Currently table contains approx 3.5 Million rows and its keep growing, the table definition is as below
[DEVICE_ID] [decimal](19, 5) NULL,
[METER_ID] [decimal](19, 5) NULL,
[DATE_TIME] [decimal](19, 5) NULL,
[COL1] [decimal](19, 5) NULL,
[COL2] [decimal](19, 5) NULL,
.
.
.
.
[COL25] [decimal](19, 5) NULL
I have created non clustered index on Date_Time column, and to note there is no unique column exists if it requires I can create identity column (Auto increment) to this but my report generation logic is totally based on Date_Time column.
I usually fire the query based on time, I.e. if I need to calculate the variation occurred in the col1 in the month period. I will need the value of Col1 on first value of 1st day and last value of last day of month, like wise i need to fire the query for flexible dates and I usually need only opening value and closing value based on Date_Time column for any chosen column.
To get first value of col1 for the first day, the query is
select top (1) COL1 from VALUEDATA where DeviceId=#DId and MeterId =#MId and Date_Time between #StartDateTime and #EndDateTime order by Date_Time
To get last value of col1 for the last day, the query is
select top (1) COL1 from VALUEDATA where DeviceId=#DId and MeterId =#MId and Date_Time between #StartDateTime and #EndDateTime order by Date_Time desc
But when I fire the above queries its takes approx 20~30 seconds, I believe this can be further optimized but don't know the way ahead.
One thought i given to this is to create another table and insert first and last row on every day basis and fetch data from this. But I will avoid the same if I can do something in existing table and query.
It’s greatly appreciable if someone can provide the inputs for the same.

To fully optimize those queries you need two different multiple indexes :
CREATE INDEX ix_valuedata_asc ON VALUEDATA (DeviceId, MeterId, Date_Time);
CREATE INDEX ix_valuedata_des ON VALUEDATA (DeviceId, MeterId, Date_Time DESC);

I have another suggestion: if your goal is to get the values of COL1, COL2 etc after you do the index lookup, the solution with just a nonclustered index on the filtering columns still has to join back to the main table, ie; do a bookmark / RID lookup.
Your info gives me the impression your base table does is not clustered (has no clustered index); is in fact a heap table
If most of your querys on the table follow the pattern you describe, I would make this table clustered. In contrary what most people think, you do not have to define an clustered index as the (unique) primary key. If you define a clustered index in SQL server on non unique data, SQL server will make it unique 'under water' by adding an invisible row identifier...
If the main, most often USED selection / filter criteria on this table is date time, I would change the table to the following clustered structure:
First, remove all non clustered indexes
Then add the following clustered index:
CREATE CLUSTERED INDEX clix_valuedata ON VALUEDATA (Date_Time, DeviceId, MeterId);
When using query's that follow your pattern, you (probably!) will get very performant Clustered index SEEK style access to your table if you look at the query explain plan.. You will now get all the other columns in the table for free, as bookmark lookups are not needed anymore. This approach will probably scale better too as the table grows; because of the SEEK behaviour...

Adding row to Table - Primary Key/Auto Increment Error(System.Data.SQLite)

I'm trying to insert a new row into a database which has four fields, the first is a primary key set as auto incrementing (integer) and the other three are strings.
I insert a new with the following statement:
INSERT INTO Manufacturer VALUES
('Test1','Test2','01332232321')
But I am given the following exception:
"SQLite error\r\ntable Manufacturer
has 4 columns but 3 values were
supplied"
I assumed that the primary key field can be omitted as the database would automatically assign and increment the value for me.
How would I go about fixing this? Is this a simple syntatical error or do I need to rethink my approach completely?

You have to specify columns:
INSERT INTO Manufacturer (col2, col3, col4) VALUES ('Test1','Test2','01332232321')
or pass the NULL value for primary key column.

I think you're looking for how to AUTOINCREMENT in sqllite
also How do I create an AUTOINCREMENT field