I have set my column to int not null default 1... but whenever I save my record, it sets default value for that record to be 0.
I am not setting it anywhere. I don't know where I am making a mistake.
I have debugged my code , and when I am passing new entity object it is setting default value for not null to 0 .May be it is something with LINQ, But I don't know how to handle it.I don't want to explicitly assign value.
Thanks!
For sql-server, you can use SQL Server Profiler to catch all the scripts you run into the DB.
This may show you some details
Try running this query, replacing the 'myTable' and 'myColumn' values with your actual TABLE and COLUMN names, and see what's returned:
SELECT
OBJECT_NAME(C.object_id) AS [Table Name]
,C.Name AS [Column Name]
,DC.Name AS [Constraint Name]
,DC.Type_Desc AS [Constraint Type]
,DC.Definition AS [Default Value]
FROM sys.default_constraints DC
INNER JOIN sys.Columns C
ON DC.parent_column_id = C.column_id
AND DC.parent_object_id = C.object_id
WHERE OBJECT_NAME(DC.parent_object_id) = 'myTable'
AND COL_NAME(DC.parent_object_id,DC.parent_column_id) = 'myColumn'
;
Should return something like this:
[Table Name] [Column Name] [Constraint Name] [Constraint Type] [Default Value]
-------------------------------------------------------------------------------------------
myTable myColumn DF_myTable_myColumn DEFAULT_CONSTRAINT ('0')
If the [Default Value] returned is indeed (1), then it means that you have set the constraint properly and something else is at play here. It might be a trigger, or some other automated DML that you've forgotten/didn't know about, or something else entirely.
I am not the world's biggest fan of using a TRIGGER, but in a case like this, it could be handy. I find that one of the best uses for a TRIGGER is debugging little stuff like this - because it lets you see what values are being passed into a table without having to scroll through mountains of profiler data. You could try something like this (again, switching out the myTable and myColumn values with your actual table and column names):
CREATE TABLE Default_Check
(
Action_Time DATETIME NOT NULL DEFAULT GETDATE()
,Inserted_Value INT
);
CREATE TRIGGER Checking_Default ON myTable
AFTER INSERT, UPDATE
AS
BEGIN
INSERT INTO Default_Check (Inserted_Value)
SELECT I.myColumn
FROM Inserted I
;
END
;
This trigger would simply list the date/time of an update/insert done against your table, as well as the inserted value. After creating this, you could run a single INSERT statement, then check:
SELECT * FROM Default_Check;
If you see one row, only one action (insert/update) was done against the table. If you see two, something you don't expect is happening - you can check to see what. You will also see here when the 0 was inserted/updated.
When you're done, just make sure you DROP the trigger:
DROP TRIGGER Checking_Default;
You'll want to DROP the table, too, once it's become irrelevant:
DROP TABLE Default_Check;
If all of this still didn't help you, let me know.
In VB use
Property VariableName As Integer? = Nothing
And
In C# use
int? value = 0;
if (value == 0)
{
value = null;
}
Please check My Example:
create table emp ( ids int null, [DOJ] datetime NOT null)
ALTER TABLE [dbo].[Emp] ADD CONSTRAINT DF_Emp_DOJ DEFAULT (GETDATE()) FOR [DOJ]
1--Not working for Default Values
insert into emp
select '1',''
2 ---working for Default Values
insert into emp(ids) Values(13)
select * From emp
I have SQL Server database and I want to change the identity column because it started
with a big number 10010 and it's related with another table, now I have 200 records and I want to fix this issue before the records increases.
What's the best way to change or reset this column?
You can not update identity column.
SQL Server does not allow to update the identity column unlike what you can do with other columns with an update statement.
Although there are some alternatives to achieve a similar kind of requirement.
When Identity column value needs to be updated for new records
Use DBCC CHECKIDENT which checks the current identity value for the table and if it's needed, changes the identity value.
DBCC CHECKIDENT('tableName', RESEED, NEW_RESEED_VALUE)
When Identity column value needs to be updated for existing records
Use IDENTITY_INSERT which allows explicit values to be inserted into the identity column of a table.
SET IDENTITY_INSERT YourTable {ON|OFF}
Example:
-- Set Identity insert on so that value can be inserted into this column
SET IDENTITY_INSERT YourTable ON
GO
-- Insert the record which you want to update with new value in the identity column
INSERT INTO YourTable(IdentityCol, otherCol) VALUES(13,'myValue')
GO
-- Delete the old row of which you have inserted a copy (above) (make sure about FK's)
DELETE FROM YourTable WHERE ID=3
GO
--Now set the idenetity_insert OFF to back to the previous track
SET IDENTITY_INSERT YourTable OFF
If got your question right you want to do something like
update table
set identity_column_name = some value
Let me tell you, it is not an easy process and it is not advisable to use it, as there may be some foreign key associated on it.
But here are steps to do it, Please take a back-up of table
Step 1- Select design view of the table
Step 2- Turn off the identity column
Now you can use the update query.
Now redo the step 1 and step 2 and Turn on the identity column
Reference
You need to
set identity_insert YourTable ON
Then delete your row and reinsert it with different identity.
Once you have done the insert don't forget to turn identity_insert off
set identity_insert YourTable OFF
--before running this make sure Foreign key constraints have been removed that reference the ID.
--set table to allow identity to be inserted
SET IDENTITY_INSERT yourTable ON;
GO
--insert everything into a temp table
SELECT *
INTO #tmpYourTable
FROM yourTable
--clear your table
DELETE FROM yourTable
--insert back all the values with the updated ID column
INSERT INTO yourTable (IDCol, OtherCols)
SELECT ID+1 as updatedID --put any other update logic to the ID here
, OtherCols FROM #tmpYourTable
--drop the temp table
DROP TABLE #tmpYourTable
--put identity back to normal
SET IDENTITY_INSERT yourTable OFF;
GO
Try using DBCC CHECKIDENT:
DBCC CHECKIDENT ('YourTable', RESEED, 1);
SET IDENTITY_INSERT dbo.TableName ON
INSERT INTO dbo.TableName
(
TableId, ColumnName1, ColumnName2, ColumnName3
)
VALUES
(
TableId_Value, ColumnName1_Value, ColumnName2_Value, ColumnName3_Value
)
SET IDENTITY_INSERT dbo.TableName OFF
When using Identity_Insert don't forget to include the column names because sql will not allow you to insert without specifying them
DBCC CHECKIDENT(table_name, RESEED, value)
table_name = give the table you want to reset value
value=initial value to be zero,to start identity column with 1
copy your table to a new table without identity column.
select columns into newtable from yourtable
add an identity column to newtable with new seed and make it as a primary key
ALTER TABLE tableName ADD id MEDIUMINT NOT NULL AUTO_INCREMENT KEY
You can also use SET IDENTITY INSERT to allow you to insert values into an identity column.
Example:
SET IDENTITY_INSERT dbo.Tool ON
GO
And then you can insert into an identity column the values you need.
I had similar problem I needed update some IDs what I did was ( i needed to Increase them by 10k ):
set identity_insert YourTable ON
INSERT INTO YourTable
([ID]
,[something1]
,[something2]
,[something3])
SELECT
([ID] + 10000)
,[something1]
,[something2]
,[something3])
FROM YourTable
WHERE something1 = 'needs updeted id'
AND something2 = 'some other condition'
set identity_insert YourTable OFF
DELETE FROM YourTable
WHERE ID >= 'your old ID From'
AND ID <= 'Your old ID To'
And that's it. Hope you understand this logic, in my case there was also PK-FK keys connection with other tables, which meant i had to update them, before i could delete from 'YourTable' original rows.
I know there is already answers to this I just wanted to leave SQL query as example,
ALTER TABLE tablename add newcolumn int
update tablename set newcolumn=existingcolumnname
ALTER TABLE tablename DROP COLUMN existingcolumnname;
EXEC sp_RENAME 'tablename.oldcolumn' , 'newcolumnname', 'COLUMN'
update tablename set newcolumnname=value where condition
However above code works only if there is no primary-foreign key relation
Complete solution for C# programmers using command builder
First of all, you have to know this facts:
In any case, you cannot modify an identity column, so you have to delete the row and re-add with new identity.
You cannot remove the identity property from the column (you would have to remove to column)
The custom command builder from .net always skips the identity column, so you cannot use it for this purpose.
So, once knowing that, what you have to do is. Either program your own SQL Insert statement, or program you own insert command builder. Or use this one that I'be programmed for you. Given a DataTable, generates the SQL Insert script:
public static string BuildInsertSQLText ( DataTable table )
{
StringBuilder sql = new StringBuilder(1000,5000000);
StringBuilder values = new StringBuilder ( "VALUES (" );
bool bFirst = true;
bool bIdentity = false;
string identityType = null;
foreach(DataRow myRow in table.Rows)
{
sql.Append( "\r\nINSERT INTO " + table.TableName + " (" );
foreach ( DataColumn column in table.Columns )
{
if ( column.AutoIncrement )
{
bIdentity = true;
switch ( column.DataType.Name )
{
case "Int16":
identityType = "smallint";
break;
case "SByte":
identityType = "tinyint";
break;
case "Int64":
identityType = "bigint";
break;
case "Decimal":
identityType = "decimal";
break;
default:
identityType = "int";
break;
}
}
else
{
if ( bFirst )
bFirst = false;
else
{
sql.Append ( ", " );
values.Append ( ", " );
}
sql.Append ("[");
sql.Append ( column.ColumnName );
sql.Append ("]");
//values.Append (myRow[column.ColumnName].ToString() );
if (myRow[column.ColumnName].ToString() == "True")
values.Append("1");
else if (myRow[column.ColumnName].ToString() == "False")
values.Append("0");
else if(myRow[column.ColumnName] == System.DBNull.Value)
values.Append ("NULL");
else if(column.DataType.ToString().Equals("System.String"))
{
values.Append("'"+myRow[column.ColumnName].ToString()+"'");
}
else
values.Append (myRow[column.ColumnName].ToString());
//values.Append (column.DataType.ToString() );
}
}
sql.Append ( ") " );
sql.Append ( values.ToString () );
sql.Append ( ")" );
if ( bIdentity )
{
sql.Append ( "; SELECT CAST(scope_identity() AS " );
sql.Append ( identityType );
sql.Append ( ")" );
}
bFirst = true;
sql.Append(";");
values = new StringBuilder ( "VALUES (" );
} //fin foreach
return sql.ToString ();
}
There's a few ways to do this as I've seen., but the best and faster way in my opinion is the following one:
The identity columns have a counter that isn't necessarily the same as the columns registered, you can see the value of this counter with the folowing SQL command:
DBCC CHECKIDENT('tableName', NORESEED);
Then, if you want to edit the identity column you will not be able, but I recommend to make a new register after reseeding the counter to the number you need. To reseed the counter use this command:
DBCC CHECKIDENT('tableName', RESEED, desiredNumber);
I have solved this problem firstly using DBCC and then using insert. For example if your table is
Firstly set new current ID Value on the table as NEW_RESEED_VALUE
MyTable {
IDCol,
colA,
colB
}
DBCC CHECKIDENT('MyTable', RESEED, NEW_RESEED_VALUE)
then you can use
insert into MyTable (colA, ColB) select colA, colB from MyTable
This would duplicate all your records but using new IDCol value starting as NEW_RESEED_VALUE. You can then remove higher ID Value duplicate rows once your have removed/moved their foreign key references, if any.
You can create a new table using the following code.
SELECT IDENTITY (int, 1, 1) AS id, column1, column2
INTO dbo.NewTable
FROM dbo.OldTable
Then delete the old db, and rename the new db to the old db's name. Note: that column1 and column2 represent all the columns in your old table that you want to keep in your new table.
I did the following:
MOVE related data into temporary storage
UPDATE primary key/identity column value (dropping and creating constraints)
RE-INSERT related data with new foreign key value
I wrapped my solution in a STORED PROCEDURE:
CREATE PROCEDURE [dbo].[UpdateCustomerLocationId]
#oldCustomerLocationId INT,
#newCustomerLocationId INT
AS
/*
Updates CustomerLocation.CustomerLocationId #oldCustomerLocationId to #newCustomerLocationId
Example:
EXEC [dbo].[UpdateCustomerLocationId]
#oldCustomerLocationId = 6154874,
#newCustomerLocationId = 50334;
*/
BEGIN
SET NOCOUNT ON;
-- exit if #oldCustomerLocationId does not exists
IF NOT EXISTS (SELECT * FROM dbo.CustomerLocation cl WHERE cl.CustomerLocationId = #oldCustomerLocationId)
BEGIN
PRINT CONCAT('CustomerLocationId ''', #oldCustomerLocationId, ''' (#oldCustomerLocationId) does not exist in dbo.CustomerLocation');
RETURN 1; -- 0 = success, > 0 = failure
END
-- exit if #newCustomerLocationId already exists
IF EXISTS (SELECT * FROM dbo.CustomerLocation cl WHERE cl.CustomerLocationId = #newCustomerLocationId)
BEGIN
PRINT CONCAT('CustomerLocationId ''', #newCustomerLocationId, ''' (#newCustomerLocationId) already exists in dbo.CustomerLocation');
RETURN 2; -- 0 = success, > 0 = failure
END
BEGIN TRAN;
BEGIN -- MOVE related data into temporary storage
IF EXISTS (SELECT * FROM dbo.CustomerLocationData t WHERE t.CustomerLocationId = #oldCustomerLocationId) BEGIN
IF OBJECT_ID('tempdb..#CustomerLocationData') IS NOT NULL
DROP TABLE #CustomerLocationData;
SELECT * INTO #CustomerLocationData FROM dbo.CustomerLocationData t WHERE t.CustomerLocationId = #oldCustomerLocationId;
DELETE t FROM dbo.CustomerLocationData t WHERE t.CustomerLocationId = #oldCustomerLocationId;
END
END
BEGIN -- UPDATE dbo.CustomerLocation
-- DROP CONSTRAINTs
ALTER TABLE [dbo].[CustomerLocation] DROP CONSTRAINT [UC_CustomerLocation];
-- INSERT OLD record with new CustomerLocationId
SET IDENTITY_INSERT dbo.CustomerLocation ON;
INSERT INTO dbo.CustomerLocation
(
CustomerLocationId, CustomerId, LocationId, CustomerLocationIdent, CustomerLocationIdent2, LocationIdent, LocationName, CustomerDistrictId,
CustomerLocationGUID, UpdatedOn, IssueManager, EnrollSelfMonitoring, TemperatureControlDeadlineHour, CreatedOn, OperationBegin, ActiveCustomer,
Comments, LocationName2, ParentGroup, TempString1, TempString2, TempString3, TempString4, TempString5, AutoInheritFromLocation, ClassificationPrimary
)
SELECT #newCustomerLocationId AS CustomerLocationId, CustomerId,LocationId, CustomerLocationIdent, CustomerLocationIdent2, LocationIdent, LocationName, CustomerDistrictId,
CustomerLocationGUID, UpdatedOn, IssueManager, EnrollSelfMonitoring, TemperatureControlDeadlineHour, CreatedOn, OperationBegin, ActiveCustomer,
Comments,LocationName2, ParentGroup, TempString1, TempString2, TempString3, TempString4, TempString5, AutoInheritFromLocation, ClassificationPrimary
FROM dbo.CustomerLocation
WHERE CustomerLocationId = #oldCustomerLocationId;
SET IDENTITY_INSERT dbo.CustomerLocation OFF;
-- DELETE OLD record
DELETE cl FROM dbo.CustomerLocation cl WHERE cl.CustomerLocationId = #oldCustomerLocationId;
-- ADD CONSTRAINTS
ALTER TABLE [dbo].[CustomerLocation] ADD CONSTRAINT [UC_CustomerLocation] UNIQUE NONCLUSTERED ([CustomerId], [LocationId]);
END
BEGIN -- re-INSERT related data from temporary storage
IF OBJECT_ID('tempdb..#CustomerLocationData') IS NOT NULL BEGIN
SET IDENTITY_INSERT dbo.CustomerLocationData ON;
INSERT INTO dbo.CustomerLocationData (Guid, CustomerLocationId, CustomerLocationDataTypeId, Date, Category, Data)
SELECT Guid, #newCustomerLocationId CustomerLocationId, CustomerLocationDataTypeId, Date, Category, Data FROM #CustomerLocationData;
SET IDENTITY_INSERT dbo.CustomerLocationData OFF;
END
END
COMMIT TRAN;
END
This happened to me because I did a merge that was updating the ID that I was doing the Merge on.
Example that did not work (note ClownID):
MERGE ArchitectMain.dbo.BackendClowns AS TGT
USING (
SELECT ClownID
,ClownName
,Description
,Active
,EmailSubject
,AddedBy
,Added
FROM #temptable1
) AS SRC(ClownID, ClownName, Description, Active, EmailSubject, AddedBy, Added)
ON (TGT.ClownID = SRC.ClownID)
WHEN MATCHED
THEN
UPDATE
SET ClownID = SRC.ClownID
,ClownName = SRC.ClownName
,Description = SRC.Description
,Active = SRC.Active
,EmailSubject = SRC.EmailSubject
,AddedBy = SRC.AddedBy
,Added = SRC.Added;
Example that worked (note ClownID):
MERGE ArchitectMain.dbo.BackendClowns AS TGT
USING (
SELECT ClownID
,ClownName
,Description
,Active
,EmailSubject
,AddedBy
,Added
FROM #temptable1
) AS SRC(ClownID, ClownName, Description, Active, EmailSubject, AddedBy, Added)
ON (TGT.ClownID = SRC.ClownID)
WHEN MATCHED
THEN
UPDATE
SET ClownName = SRC.ClownName
,Description = SRC.Description
,Active = SRC.Active
,EmailSubject = SRC.EmailSubject
,AddedBy = SRC.AddedBy
,Added = SRC.Added;
Update is not allowed:
but you can
INSERT new data with correct key
Delete reg
import: all fields must be declared in insert into
sample: reg 5 must be changed to 4:
set IDENTITY_INSERT Gastos_ReclamacionCausa on
insert into Gastos_ReclamacionCausa
(IDCausa,TextoCombo,Asunto,Mensaje,EsBaja)
select 4,TextoCombo,Asunto,Mensaje,EsBaja from Gastos_ReclamacionCausa where idcausa=5
delete from Gastos_ReclamacionCausa where idcausa = 5
set IDENTITY_INSERT Gastos_ReclamacionCausa off
If you specifically need to change the primary key value to a different number (ex 123 -> 1123). The identity property blocks changing a PK value. Set Identity_insert isn't going to work. Doing an Insert/Delete is not advisable if you have cascading deletes (unless you turn off referential integrity checking).
EDIT: Newer versions of SQL don't allow changing the syscolumns entity, so part of my solution has to be done the hard way. Refer to this SO on how to remove Identity from a primary key instead:
Remove Identity from a column in a table
This script will turn off identity on a PK:
***********************
sp_configure 'allow update', 1
go
reconfigure with override
go
update syscolumns set colstat = 0 --turn off bit 1 which indicates identity column
where id = object_id('table_name') and name = 'column_name'
go
exec sp_configure 'allow update', 0
go
reconfigure with override
go
***********************
Next, you can set the relationships so they'll update the foreign key references. Or else you need to turn off relationship enforcement. This SO link shows how:
How can foreign key constraints be temporarily disabled using T-SQL?
Now, you can do your updates. I wrote a short script to write all my update SQL based on the same column name (in my case, I needed to increase the CaseID by 1,000,000:
select
'update ['+c.table_name+'] SET ['+Column_Name+']=['+Column_Name+']+1000000'
from Information_Schema.Columns as c
JOIN Information_Schema.Tables as t ON t.table_Name=c.table_name and t.Table_Schema=c.table_schema and t.table_type='BASE TABLE'
where Column_Name like 'CaseID' order by Ordinal_position
Lastly, re-enable referential integrity and then re-enable the Identity column on the primary key.
Note: I see some folks on these questions ask WHY. In my case, I have to merge data from a second production instance into a master DB so I can shut down the second instance. I just need all the PK/FKs of operations data to not collide. Meta-data FKs are identical.
To truncate a table in SQLite I need to use this syntax:
DELETE FROM someTable
But how do I truncate the table only if it exists?
Unfortunately this throws an error:
DELETE FROM someTable IF EXISTS
This doesn't work either:
DELETE IF EXISTS FROM someTable
Thanks.
It is the two step process:
Delete all data from that table using:
Delete from TableName
Then:
DELETE FROM SQLITE_SEQUENCE WHERE name='TableName';
IMHO, it is more efficient to drop the table and re-create it. And yes, you can use "IF EXISTS" in this case.
Just do delete. This is from the SQLite documentation:
The Truncate Optimization
"When the WHERE is omitted from a DELETE statement and the table being deleted has no triggers, SQLite uses an optimization to erase the entire table content without having to visit each row of the table individually. This "truncate" optimization makes the delete run much faster. Prior to SQLite version 3.6.5, the truncate optimization also meant that the sqlite3_changes() and sqlite3_total_changes() interfaces and the count_changes pragma will not actually return the number of deleted rows. That problem has been fixed as of version 3.6.5."
I got it to work with:
SQLiteDatabase db= this.getWritableDatabase();
db.delete(TABLE_NAME, null, null);
SELECT name FROM sqlite_master where name = '<TABLE_NAME_HERE>'
If the table name does not exist then there would not be any records returned!
You can as well use
SELECT count(name) FROM sqlite_master where name = '<TABLE_NAME_HERE>'
if the count is 1, means table exists, otherwise, it would return 0
After deleting I'm also using VACUUM command. So for full TRUNCATE equivalent I use this code:
DELETE FROM <table>;
UPDATE SQLITE_SEQUENCE SET seq = 0 WHERE name = '<table>';
VACUUM;
Deleting isn't working for me for reset Auto Increment
DELETE FROM "sqlite_sequence" WHERE "name"='<table>';
To read more about VACUUM you can go here: https://blogs.gnome.org/jnelson/2015/01/06/sqlite-vacuum-and-auto_vacuum/
Unfortunately, we do not have a "TRUNCATE TABLE" command in SQLite, but you can use SQLite's DELETE command to delete the complete data from an existing table, though it is recommended to use the DROP TABLE command to drop the complete table and re-create it once again.
"sqllite" dosn't have "TRUNCATE " order like than mysql, then we have to get other way...
this function (reset_table) frist delete all data in table and then reset AUTOINCREMENT key in table....
now you can use this function every where you want...
example :
private SQLiteDatabase mydb;
private final String dbPath = "data/data/your_project_name/databases/";
private final String dbName = "your_db_name";
public void reset_table(String table_name){
open_db();
mydb.execSQL("Delete from "+table_name);
mydb.execSQL("DELETE FROM SQLITE_SEQUENCE WHERE name='"+table_name+"';");
close_db();
}
public void open_db(){
mydb = SQLiteDatabase.openDatabase(dbPath + dbName + ".db", null, SQLiteDatabase.OPEN_READWRITE);
}
public void close_db(){
mydb.close();
}
**It is Simple, just follow 2 steps.
Step #1. Fire query "Delete from tableName", It will delete all records from table.
Step #2. There is table named "sqlite_sequence" in Sqlite Database, just browse it and you can set sequence table wise to "0" so it will start from auto id "1".**
See the screenshot attached.
there is no truncate command in sqlite.
but can be achieved by:
delete all records;
Delete from 'Table1';
then
set auto-increment to 0;
UPDATE SQLITE_SEQUENCE SET seq = 0 WHERE name = 'Table1';