I need to update an existing table by adding a new column with default value as UUID and datatype as VARCHAR(255).
I tried to achieved it by writing a function as:
CREATE FUNCTION UUID_FUNC()
RETURNS VARCHAR(255)
LANGUAGE SQL
BEGIN ATOMIC
DECLARE UUID VARCHAR(4000);
SET UUID = (SELECT TRIM(CHAR(HEX(GENERATE_UNIQUE()))) from sysibm.sysdummy1);
RETURN UUID;
END
And used it in the query as:
ALTER TABLE <Table-name>
ADD ID_VALUE VARCHAR(255) NOT NULL DEFAULT (UUID_FUNC())
Got following error when executing the above query:
SQL Error [42601]: An unexpected token "DEFAULT" was found following "ARCHAR(255) NOT NULL".
Expected tokens may include: "CHECK".. SQLCODE=-104, SQLSTATE=42601, DRIVER=3.59.81
What is the correct format for calling custom defined functions in ALTER query or any suggestions to achieve the above requirement is appreciated.
Thanks in advance.
I was able to achieve it in following way:
ALTER TABLE <Table-name> ADD ID_VALUE VARCHAR(255) NOT NULL DEFAULT '0';
UPDATE <Table-name> SET ID_VALUE=(hex(GENERATE_UNIQUE())) WHERE ID_VALUE='0';
You would need to do this via a trigger, rather than as a generated expression. Given the DDL:
create or replace function your.uuid_func()
returns char(26)
language sql
not deterministic
return values(hex(generate_unique()));
create table your.table (
c1 int not null,
c2 char(26) not null
);
You can create the trigger:
create trigger set_uuid
before insert on your.table
referencing new as n
for each row
when (n.id_value is null)
set n.id_value = your.uuid_func();
Then the insert:
—- You can insert a normal string:
insert into your.table (c1, c2)
values (1, ‘anything’);
—- Or, if you don’t provide a value for c2, it will be set
—- to the value of UUID_FUNC():
insert into your.table (c1)
values (2);
Results:
select * from your.table;
C1 C2
----------- --------------------------
1 anything
2 20200111154913255440000000
ALTER TABLE ADD ID_VALUE AS (UUID_FUNC());
For accessing existing field values,
ALTER TABLE ADD ID_VALUE AS (UUID_FUNC([field_name]));
Related
Currently exploring different ways to identify deltas. I've got something using a change capture stream, but wanted to get something working on a table with change tracking enabled as an alternative option.
This is what I attempted to do:
create or replace table T1 (
id number(8) not null,
c1 varchar(255) default null
);
create or replace table T1_MERGED_OUTPUT (
id number(8) not null,
c1 varchar(255) default null
);
create or replace table DELTA_UPDATE_TIMES (
id number(8) not null,
table_name varchar(255) not null,
last_update_datetime TIMESTAMP_TZ default current_timestamp()
);
alter table t1 set change_tracking = true;
T1 is the source table with change tracking enabled. T1_MERGED_OUTPUT will be loaded with the incremental updates. DELTA_UPDATE_TIMES holds the times of when each table was updated. To get the latest update timestamps for each table, I've defined a UDF:
CREATE OR REPLACE FUNCTION TABLE_LAST_UPDATE_DATETIME(tbl VARCHAR)
RETURNS TIMESTAMP_TZ
AS
$$
SELECT MAX(LASTEST_UPDATE_DATETIME) FROM DELTA_UPDATE_TIMES WHERE TABLE_NAME = tbl
$$;
Then I tried to create another UDF to get the changes between the last update time and the current time like this:
CREATE OR REPLACE FUNCTION DATA_LAST_UPDATE_DATETIME(start_time TIMESTAMP_TZ)
RETURNS TABLE(ID NUMBER, C1 VARCHAR, ACTION_NAME VARCHAR, IS_UPDATE BOOLEAN)
AS
$$
select ID, C1, METADATA$ACTION AS ACTION_NAME, METADATA$ISUPDATE AS IS_UPDATE
from t1
changes(information => default)
at(timestamp => start_time)
end(timestamp => current_timestamp())
$$;
But I'm getting this error: SQL compilation error: error line 2 at position 29 invalid identifier 'METADATA$ACTION'
When I run that query outside of the function, it works correct and the action and is_update is returned.
Any ideas what the issue is here and whether there is a way round it?
I have a table with ID as identity column, and Code as a varchar column. Code's default value is set to a scalar function X.
Inside that scalar function X, getting the scope_identity() or ##identity returns null. Is there a way to get the inserted identity without using insert trigger?
Any help is greatly appreciated
You could just skip the ID and IDENTITY altogether and generate the code as the primary key. EG
--drop table if exists t
--drop sequence t_seq
--drop function t_key_gen
go
create sequence t_seq start with 1000 increment by 1
go
create or alter function t_key_gen(#i int)
returns char(10)
as
begin
return concat('AB',right(concat('0000000000',#i),8));
end
go
create table t(code char(10) primary key default dbo.t_key_gen(next value for t_seq), a int)
go
insert into t(a) values (1),(2),(3)
select * from t
In my SQL Server 2012 environment, I've created a series of stored procedures that pass pre-existing temporary tables among themselves (I have tried different architectures here, but wasn't able to bypass this due to the nature of the requirements / procedures).
What I'm trying to do is to, within a stored procedure check if a temporary table has already been created and, if not, to create it.
My current SQL looks as follows:
IF OBJECT_ID('tempdb..#MyTable') IS NULL
CREATE TABLE #MyTable
(
Col1 INT,
Col2 VARCHAR(10)
...
);
But when I try and run it when the table already exists, I get the error message
There is already an object named '#MyTable' in the database
So it seems it doesn't simply ignore those lines within the If statement.
Is there a way to accomplish this - create a temp table if it doesn't already exist, otherwise, use the one already in memory?
Thanks!
UPDATE:
For whatever reason, following #RaduGheorghiu's suggestion from the comments, I found out that the system creates a temporary table with a name along the lines of dbo.#MyTable________________________________________________0000000001B1
Is that why I can't find it? Is there any way to change that? This is new to me....
Following the link here, http://weblogs.sqlteam.com/mladenp/archive/2008/08/21/SQL-Server-2005-temporary-tables-bug-feature-or-expected-behavior.aspx
It seems as though you need to use the GO statement.
You meant to use IS NOT NULL i think... this is commonly used to clear temp tables so you don't get the error you mentioned in your OP.
IF OBJECT_ID('tempdb..#MyTable') IS NOT NULL DROP TABLE #MyTable
CREATE TABLE #MyTable
(
Col1 INT,
Col2 VARCHAR(10)
);
The big difference is the DROP TABLE statement after you do your logical check. Also, creating your table without filling data doesn't make it NULL
DROP TABLE #MyTable
CREATE TABLE #MyTable
(
Col1 INT,
Col2 VARCHAR(10)
);
IF OBJECT_ID('tempdb..#MyTable') IS NOT NULL
SELECT 1
Try wrapping your actions in a begin...end block:
if object_id('tempdb..#MyTable') is null
begin
create table #MyTable (
Col1 int
, Col2 varchar(10)
);
end
This seems odd, but it works when I try it
IF(OBJECT_ID('tempdb..#Test') IS NULL) --check if it exists
BEGIN
IF(1 = 0)--this will never actually run, but it tricks the parser into allowing the CREATE to run
DROP TABLE #Test;
PRINT 'Create table';
CREATE TABLE #Test
(
ID INT NOT NULL PRIMARY KEY
);
END
IF(NOT EXISTS(SELECT 1 FROM #Test))
INSERT INTO #Test(ID)
VALUES(1);
SELECT *
FROM #Test;
--Try dropping the table and test again
--DROP TABLE #Test;
I have a table that has several nullable integer columns. This is undesirable for several reasons, so I am looking to update all nulls to 0 and then set these columns to NOT NULL. Aside from changing nulls to 0, data must be preserved.
I am looking for the specific SQL syntax to alter a column (call it ColumnA) to "not null". Assume the data has been updated to not contain nulls.
Using SQL server 2000.
First, make all current NULL values disappear:
UPDATE [Table] SET [Column]=0 WHERE [Column] IS NULL
Then, update the table definition to disallow "NULLs":
ALTER TABLE [Table] ALTER COLUMN [Column] INTEGER NOT NULL
I had the same problem, but the field used to default to null, and now I want to default it to 0. That required adding one more line after mdb's solution:
ALTER TABLE [Table] ADD CONSTRAINT [Constraint] DEFAULT 0 FOR [Column];
You will have to do it in two steps:
Update the table so that there are no nulls in the column.
UPDATE MyTable SET MyNullableColumn = 0
WHERE MyNullableColumn IS NULL
Alter the table to change the property of the column
ALTER TABLE MyTable
ALTER COLUMN MyNullableColumn MyNullableColumnDatatype NOT NULL
For Oracle 11g, I was able to change the column attribute as follows:
ALTER TABLE tablename MODIFY columnname datatype NOT NULL;
Otherwise abatichev's answer seemed good. You can't repeat the alter - it complains (at least in SQL Developer) that the column is already not null.
this worked for me:
ALTER TABLE [Table]
Alter COLUMN [Column] VARCHAR(50) not null;
As long as the column is not a unique identifier
UPDATE table set columnName = 0 where columnName is null
Then
Alter the table and set the field to non null and specify a default value of 0
In case of FOREIGN KEY CONSTRAINT... there will be a problem if '0' is not present in the column of Primary key table. The solution for that is...
STEP1:
Disable all the constraints using this code :
EXEC sp_msforeachtable "ALTER TABLE ? NOCHECK CONSTRAINT all"
STEP2:
RUN UPDATE COMMAND (as mentioned in above comments)
RUN ALTER COMMAND (as mentioned in above comments)
STEP3:
Enable all the constraints using this code :
exec sp_msforeachtable #command1="print '?'", #command2="ALTER TABLE ? WITH CHECK CHECK CONSTRAINT all"
this seems simpler, but only works on Oracle:
ALTER TABLE [Table]
ALTER [Column] NUMBER DEFAULT 0 NOT NULL;
in addition, with this, you can also add columns, not just alter it.
It updates to the default value (0) in this example, if the value was null.
In my case I had difficulties with the posted answers. I ended up using the following:
ALTER TABLE table_name CHANGE COLUMN column_name column_name VARCHAR(200) NOT NULL DEFAULT '';
Change VARCHAR(200) to your datatype, and optionally change the default value.
If you don't have a default value you're going to have a problem making this change, as default would be null creating a conflict.
Making column not null and adding default can also be done in the SSMS GUI.
As others have already stated, you can't set "not null" until all
the existing data is "not null" like so:
UPDATE myTable SET myColumn = 0
Once that's done, with the table in design view (right click on
table and click "design view"), you can just uncheck the Allow
Nulls columns like so:
Still in design view with the column selected, you can see the
Column Properties in the window below and set the default to 0 in there as well like so:
Let's take an example:
TABLE NAME=EMPLOYEE
And I want to change the column EMPLOYEE_NAME to NOT NULL. This query can be used for the task:
ALTER TABLE EMPLOYEE MODIFY EMPLOYEE.EMPLOYEE_NAME datatype NOT NULL;
For the inbuilt javaDB included in the JDK (Oracle's supported distribution of the Apache Derby) the below worked for me
alter table [table name] alter column [column name] not null;
You can change the definition of existing DB column using following sql.
ALTER TABLE mytable modify mycolumn datatype NOT NULL;
First make sure the column that your changing to not does not have null values
select count(*) from table where column's_name is null
Impute the missing values. you can replace the nulls with empty string or 0 or an average or median value or an interpolated value. It depends on your back fill strategy or forward fill strategy.
Decide if the column values need to be unique or non-unique. if they need to be unique than add an unique constraint. Otherwise, see if performance is adequate or if you need to add an index.
I inserted some values into a table. There is a column whose value is auto-generated. In the next statement of my code, I want to retrieve this value.
Can you tell me how to do it the right way?
##IDENTITY is not scope safe and will get you back the id from another table if you have an insert trigger on the original table, always use SCOPE_IDENTITY()
This is how I do my store procedures for MSSQL with an autogenerated ID.
CREATE PROCEDURE [dbo].[InsertProducts]
#id INT = NULL OUT,
#name VARCHAR(150) = NULL,
#desc VARCHAR(250) = NULL
AS
INSERT INTO dbo.Products
(Name,
Description)
VALUES
(#name,
#desc)
SET #id = SCOPE_IDENTITY();
This works very nicely in SQL 2005:
DECLARE #inserted_ids TABLE ([id] INT);
INSERT INTO [dbo].[some_table] ([col1],[col2],[col3],[col4],[col5],[col6])
OUTPUT INSERTED.[id] INTO #inserted_ids
VALUES (#col1,#col2,#col3,#col4,#col5,#col6)
It has the benefit of returning all the IDs if your INSERT statement inserts multiple rows.
If your using PHP and MySQL you can use the mysql_insert_id() function which will tell you the ID of item you Just instered.
But without your Language and DBMS I'm just shooting in the dark here.
Again no language agnostic response, but in Java it goes like this:
Connection conn = Database.getCurrent().getConnection();
PreparedStatement ps = conn.prepareStatement(insertSql, Statement.RETURN_GENERATED_KEYS);
try {
ps.executeUpdate();
ResultSet rs = ps.getGeneratedKeys();
rs.next();
long primaryKey = rs.getLong(1);
} finally {
ps.close();
}
If you are working with Oracle:
Inset into Table (Fields....) values (Values...) RETURNING (List of Fields...) INTO (variables...)
example:
INSERT INTO PERSON (NAME) VALUES ('JACK') RETURNING ID_PERSON INTO vIdPerson
or if you are calling from... Java with a CallableStatement (sry, it's my field)
INSERT INTO PERSON (NAME) VALUES ('JACK') RETURNING ID_PERSON INTO ?
and declaring an autput parameter for the statement
There's no standard way to do it (just as there is no standard way to create auto-incrementing IDs). Here are two ways to do it in PostgreSQL. Assume this is your table:
CREATE TABLE mytable (
id SERIAL PRIMARY KEY,
lastname VARCHAR NOT NULL,
firstname VARCHAR
);
You can do it in two statements as long as they're consecutive statements in the same connection (this will be safe in PHP with connection pooling because PHP doesn't give the connection back to the pool until your script is done):
INSERT INTO mytable (lastname, firstname) VALUES ('Washington', 'George');
SELECT lastval();
lastval() gives you the last auto-generated sequence value used in the current connection.
The other way is to use PostgreSQL's RETURNING clause on the INSERT statement:
INSERT INTO mytable (lastname) VALUES ('Cher') RETURNING id;
This form returns a result set just like a SELECT statement, and is also handy for returning any kind of calculated default value.
An important note is that using vendor SQL queries to retrieve the last inserted ID are safe to use without fearing about concurrent connections.
I always thought that you had to create a transaction in order to INSERT a line and then SELECT the last inserted ID in order to avoid retrieving an ID inserted by another client.
But these vendor specific queries always retrieve the last inserted ID for the current connection to the database. It means that the last inserted ID cannot be affected by other client insertions as long as they use their own database connection.
For SQL 2005:
Assuming the following table definition:
CREATE TABLE [dbo].[Test](
[ID] [int] IDENTITY(1,1) NOT NULL,
[somevalue] [nchar](10) NULL,
)
You can use the following:
INSERT INTO Test(somevalue)
OUTPUT INSERTED.ID
VALUES('asdfasdf')
Which will return the value of the ID column.
From the site i found out the following things:
SQL SERVER – ##IDENTITY vs SCOPE_IDENTITY() vs IDENT_CURRENT – Retrieve Last Inserted Identity of Record
March 25, 2007 by pinaldave
SELECT ##IDENTITY
It returns the last IDENTITY value produced on a connection, regardless of the table that produced the value, and regardless of the scope of the statement that produced the value.
##IDENTITY will return the last identity value entered into a table in your current session. While ##IDENTITY is limited to the current session, it is not limited to the current scope. If you have a trigger on a table that causes an identity to be created in another table, you will get the identity that was created last, even if it was the trigger that created it.
SELECT SCOPE_IDENTITY()
It returns the last IDENTITY value produced on a connection and by a statement in the same scope, regardless of the table that produced the value.
SCOPE_IDENTITY(), like ##IDENTITY, will return the last identity value created in the current session, but it will also limit it to your current scope as well. In other words, it will return the last identity value that you explicitly created, rather than any identity that was created by a trigger or a user defined function.
SELECT IDENT_CURRENT(‘tablename’)
It returns the last IDENTITY value produced in a table, regardless of the connection that created the value, and regardless of the scope of the statement that produced the value.
IDENT_CURRENT is not limited by scope and session; it is limited to a specified table. IDENT_CURRENT returns the identity value generated for a specific table in any session and any scope.
Remember that ##IDENTITY returns the most recently created identity for your current connection, not necessarily the identity for the recently added row in a table. You should always use SCOPE_IDENTITY() to return the identity of the recently added row.
What database are you using? As far as I'm aware, there is no database agnostic method for doing this.
This is how I've done it using parameterized commands.
MSSQL
INSERT INTO MyTable (Field1, Field2) VALUES (#Value1, #Value2);
SELECT SCOPE_IDENTITY();
MySQL
INSERT INTO MyTable (Field1, Field2) VALUES (?Value1, ?Value2);
SELECT LAST_INSERT_ID();
sql = "INSERT INTO MyTable (Name) VALUES (#Name);" +
"SELECT CAST(scope_identity() AS int)";
SqlCommand cmd = new SqlCommand(sql, conn);
int newId = (int)cmd.ExecuteScalar();
Ms SQL Server: this is good solution even if you inserting more rows:
Declare #tblInsertedId table (Id int not null)
INSERT INTO Test ([Title], [Text])
OUTPUT inserted.Id INTO #tblInsertedId (Id)
SELECT [Title], [Text] FROM AnotherTable
select Id from #tblInsertedId
Rob's answer would be the most vendor-agnostic, but if you're using MySQL the safer and correct choise would be the built-in LAST_INSERT_ID() function.
SELECT ##Scope_Identity as Id
There is also ##identity, but if you have a trigger, it will return the results of something that happened during the trigger, where scope_identity respects your scope.
insert the row with a known guid.
fetch the autoId-field with this guid.
This should work with any kind of database.
An Environment Based Oracle Solution:
CREATE OR REPLACE PACKAGE LAST
AS
ID NUMBER;
FUNCTION IDENT RETURN NUMBER;
END;
/
CREATE OR REPLACE PACKAGE BODY LAST
AS
FUNCTION IDENT RETURN NUMBER IS
BEGIN
RETURN ID;
END;
END;
/
CREATE TABLE Test (
TestID INTEGER ,
Field1 int,
Field2 int
)
CREATE SEQUENCE Test_seq
/
CREATE OR REPLACE TRIGGER Test_itrig
BEFORE INSERT ON Test
FOR EACH ROW
DECLARE
seq_val number;
BEGIN
IF :new.TestID IS NULL THEN
SELECT Test_seq.nextval INTO seq_val FROM DUAL;
:new.TestID := seq_val;
Last.ID := seq_val;
END IF;
END;
/
To get next identity value:
SELECT LAST.IDENT FROM DUAL
In TransactSQL, you can use OUTPUT clause to achieve that.
INSERT INTO my_table(col1,col2,col3) OUTPUT INSERTED.id VALUES('col1Value','col2Value','col3Value')
FRI: http://msdn.microsoft.com/en-us/library/ms177564.aspx
Simplest answer:
command.ExecuteScalar()
by default returns the first column
Return Value
Type: System.Object
The first column of the first row in the result set, or a null reference (Nothing in Visual Basic) if the result set is empty. Returns a maximum of 2033 characters.
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