Related
I'd like to add a NOT NULL column to a Redshift table that has records, an IDENTITY field, and that other tables have foreign keys to.
In PostgreSQL, you can add the column as NULL, fill it in, then ALTER it to be NOT NULL.
In Redshift, the best I've found so far is:
ALTER TABLE my_table ADD COLUMN new_column INTEGER;
-- Fill that column
CREATE TABLE my_table2 (
id INTEGER IDENTITY NOT NULL SORTKEY,
(... all the fields ... )
new_column INTEGER NOT NULL,
PRIMARY KEY(id)
) DISTSTYLE all;
UNLOAD ('select * from my_table')
to 's3://blah' credentials '<aws-auth-args>' ;
COPY my_table2
from 's3://blah' credentials '<aws-auth-args>'
EXPLICIT_IDS;
DROP table my_table;
ALTER TABLE my_table2 RENAME TO my_table;
-- For each table that had a foreign key to my_table:
ALTER TABLE another_table ADD FOREIGN KEY(my_table_id) REFERENCES my_table(id)
Is this the best way of achieving this?
You can achieve this w/o having to load to S3.
modify the existing table to create the desired column w/ a default value
update that column in some way (in my case it was copying from another column)
create a new table with the column w/o a default value
insert into the new table (you must list out the columns rather than using (*) since the order may be the same (say if you want the new column in position 2)
drop the old table
rename the table
alter table to give correct owner (if appropriate)
ex:
-- first add the column w/ a default value
alter table my_table_xyz
add visit_id bigint NOT NULL default 0; -- not null but default value
-- now populate the new column with whatever is appropriate (the key in my case)
update my_table_xyz
set visit_id = key;
-- now create the new table with the proper constraints
create table my_table_xzy_new
(
key bigint not null,
visit_id bigint NOT NULL, -- here it is not null and no default value
adt_id bigint not null
);
-- select all from old into new
insert into my_table_xyz_new
select key, visit_id, adt_id
from my_table_xyz;
-- remove the orig table
DROP table my_table_xzy_events;
-- rename the newly created table to the desired table
alter table my_table_xyz_new rename to my_table_xyz;
-- adjust any views, foreign keys or permissions as required
I want to add a column with the same value across the rows to a table. I use this:
ALTER TABLE dbo.MyTable
ADD MyColumnName VARCHAR(20) NULL
DEFAULT 'A201412'
WITH VALUES
It almost works fine but it creates some stupid constraint to a column. Other existing columns do not have any constraints. How to create a column without a constraint?
That "stupid" constraint is what the DEFAULT keyword is really used for.
Using DEFAULT when you create a column means that that value will be used when no value is specified in an INSERT for the column, for example
CREATE TABLE test (
a Int
, b Varchar(5) DEFAULT 'foo'
);
INSERT INTO test(a) VALUES (1)
will generate the row
a | b
1 | foo
instead of the row
a | b
1 | NULL
As Gordon already said, don't add the DEFAULT, then use an UPDATE to put the initial value in the new column
ALTER TABLE dbo.MyTable ADD MyColumnName VARCHAR(20);
UPDATE dbo.MyTable SET MyColumnName = 'A201412'
Just don't add the default clause. Simply use:
ALTER TABLE dbo.MyTable ADD MyColumnName VARCHAR(20);
I use MS Access (2003) database. Once I create a column I set NOT NULL using sql statement:
ALTER TABLE Table1
ALTER column myColumn INTEGER not null
Is there a way to change it back to allow null values? I already tried:
ALTER TABLE Table1
ALTER column myColumn INTEGER null
but nothing...
You cant specify null in ALTER TABLE (although not null is allowed)
See the below documentation and also this discussion on this toppic
Syntax
ALTER TABLE table {ADD {COLUMN field type[(size)] [NOT NULL] [CONSTRAINT index] | ALTER COLUMN field type[(size)] | CONSTRAINT multifieldindex} | DROP {COLUMN field I CONSTRAINT indexname} }
Old School Solution:-
create a new temporray field as null with the same datatype
update the new temporary field to the existing NOT NULL field
drop the old NOT NULL field
create the droped column with the same datatype again without NOT NULL
update the existing field to the temporary field
if there have been indices on the existing field, recreate these
drop the temporary field
Try something like this using MODIFY :-
ALTER TABLE Table1 MODIFY myColumn INT NULL;
The only way I've found is to use DAO directly on the table.
Set db.TableDefs(strTable1).Fields(strFieldName).Required = false
I’m trying to modify a table to make its primary key column AUTO_INCREMENT after the fact. I have tried the following SQL, but got a syntax error notification.
ALTER TABLE document
ALTER COLUMN document_id AUTO_INCREMENT
Am I doing something wrong or is this not possible?
+--------------------+
| VERSION() |
+--------------------+
| 5.0.75-0ubuntu10.2 |
+--------------------+
ALTER TABLE document MODIFY COLUMN document_id INT auto_increment
Roman is right, but note that the auto_increment column must be part of the PRIMARY KEY or a UNIQUE KEY (and in almost 100% of the cases, it should be the only column that makes up the PRIMARY KEY):
ALTER TABLE document MODIFY document_id INT AUTO_INCREMENT PRIMARY KEY
In my case it only worked when I put not null. I think this is a constraint.
ALTER TABLE document MODIFY COLUMN document_id INT NOT NULL AUTO_INCREMENT;
You can apply the atuto_increment constraint to the data column by the following query:
ALTER TABLE customers MODIFY COLUMN customer_id BIGINT NOT NULL AUTO_INCREMENT;
But, if the columns are part of a foreign key constraint you, will most probably receive an error. Therefore, it is advised to turn off foreign_key_checks by using the following query:
SET foreign_key_checks = 0;
Therefore, use the following query instead:
SET foreign_key_checks = 0;
ALTER TABLE customers MODIFY COLUMN customer_id BIGINT NOT NULL AUTO_INCREMENT;
SET foreign_key_checks = 1;
The SQL to do this would be:
ALTER TABLE `document` MODIFY COLUMN `document_id` INT AUTO_INCREMENT;
There are a couple of reasons that your SQL might not work. First, you must re-specify the data type (INT in this case). Also, the column you are trying to alter must be indexed (it does not have to be the primary key, but usually that is what you would want). Furthermore, there can only be one AUTO_INCREMENT column for each table. So, you may wish to run the following SQL (if your column is not indexed):
ALTER TABLE `document` MODIFY `document_id` INT AUTO_INCREMENT PRIMARY KEY;
You can find more information in the MySQL documentation: http://dev.mysql.com/doc/refman/5.1/en/alter-table.html for the modify column syntax and http://dev.mysql.com/doc/refman/5.1/en/create-table.html for more information about specifying columns.
You must specify the type of the column before the auto_increment directive, i.e. ALTER TABLE document MODIFY COLUMN document_id INT AUTO_INCREMENT.
AUTO_INCREMENT is part of the column's datatype, you have to define the complete datatype for the column again:
ALTER TABLE document
ALTER COLUMN document_id int AUTO_INCREMENT
(int taken as an example, you should set it to the type the column had before)
You can do it like this:
alter table [table_name] modify column [column_name] [column_type] AUTO_INCREMENT;
You can use the following query to make document_id to increment automatically
ALTER TABLE document MODIFY COLUMN document_id INT auto_increment
It is preferred to make document_id primary key as well
ALTER TABLE document MODIFY COLUMN document_id INT auto_increment PRIMARY KEY;
Below statement works. Note that you need to mention the data type again for the column name (redeclare the data type the column was before).
ALTER TABLE document
MODIFY COLUMN document_id int AUTO_INCREMENT;
AUTO_INCREMENT is part of the column's datatype, you have to define the complete datatype for the column again:
ALTER TABLE document
MODIFY COLUMN document_id int AUTO_INCREMENT
(int taken as an example, you should set it to the type the column had before)
If none of the above works try this. This is what I did in MYSQL and yes, you need to write the column name (document_id) twice.
ALTER TABLE document
CHANGE COLUMN document_id document_id INT(11) NOT NULL AUTO_INCREMENT ;
Setting column as primary key and auto_increment at the same time:
mysql> ALTER TABLE persons MODIFY COLUMN personID INT auto_increment PRIMARY KEY;
Query OK, 10 rows affected (0.77 sec)
Records: 10 Duplicates: 0 Warnings: 0
mysql>
To modify the column in mysql we use alter and modify keywords. Suppose we have created a table like:
create table emp(
id varchar(20),
ename varchar(20),
salary float
);
Now we want to modify type of the column id to integer with auto increment. You could do this with a command like:
alter table emp modify column id int(10) auto_increment;
Previous Table syntax:
CREATE TABLE apim_log_request (TransactionId varchar(50) DEFAULT NULL);
For changing the TransactionId to auto increment use this query
ALTER TABLE apim_log_request MODIFY COLUMN TransactionId INT auto_increment;
alter table tbl_user MODIFY COLUMN id int(10) auto_increment;
Just like this:
alter table document modify column id int(11) auto_increment;
As you are redefining the column again, you have to specify the datatype again and add auto_increment to it as it's a part of datatype.
ALTER TABLE `document` MODIFY COLUMN `document_id` INT AUTO_INCREMENT;
Try the following:
ALTER TABLE table_name MODIFY COLUMN id datatype auto_increment;
Since SQL tag is attached to the question I really think all answers missed one major point.
MODIFY command does not exist in SQL server So you will be getting an error when you run the
ALTER TABLE Satellites MODIFY COLUMN SatelliteID INT auto_increment PRIMARY KEY;
In this case you can either add new column as INT IDENTITY
ALTER TABLE Satellites
ADD ID INT IDENTITY
CONSTRAINT PK_YourTable PRIMARY KEY CLUSTERED;
OR
Fill the existing null index with incremental numbers using this method,
DECLARE #id INT
SET #id = 0
UPDATE Satellites SET #id = SatelliteID = #id + 1
Use the following queries:
ALTER TABLE YourTable DROP COLUMN IDCol
ALTER TABLE YourTable ADD IDCol INT IDENTITY(1,1)
How can I add a column with a default value to an existing table in SQL Server 2000 / SQL Server 2005?
Syntax:
ALTER TABLE {TABLENAME}
ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL}
CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
WITH VALUES
Example:
ALTER TABLE SomeTable
ADD SomeCol Bit NULL --Or NOT NULL.
CONSTRAINT D_SomeTable_SomeCol --When Omitted a Default-Constraint Name is autogenerated.
DEFAULT (0)--Optional Default-Constraint.
WITH VALUES --Add if Column is Nullable and you want the Default Value for Existing Records.
Notes:
Optional Constraint Name:
If you leave out CONSTRAINT D_SomeTable_SomeCol then SQL Server will autogenerate
a Default-Contraint with a funny Name like: DF__SomeTa__SomeC__4FB7FEF6
Optional With-Values Statement:
The WITH VALUES is only needed when your Column is Nullable
and you want the Default Value used for Existing Records.
If your Column is NOT NULL, then it will automatically use the Default Value
for all Existing Records, whether you specify WITH VALUES or not.
How Inserts work with a Default-Constraint:
If you insert a Record into SomeTable and do not Specify SomeCol's value, then it will Default to 0.
If you insert a Record and Specify SomeCol's value as NULL (and your column allows nulls),
then the Default-Constraint will not be used and NULL will be inserted as the Value.
Notes were based on everyone's great feedback below.
Special Thanks to:
#Yatrix, #WalterStabosz, #YahooSerious, and #StackMan for their Comments.
ALTER TABLE Protocols
ADD ProtocolTypeID int NOT NULL DEFAULT(1)
GO
The inclusion of the DEFAULT fills the column in existing rows with the default value, so the NOT NULL constraint is not violated.
When adding a nullable column, WITH VALUES will ensure that the specific DEFAULT value is applied to existing rows:
ALTER TABLE table
ADD column BIT -- Demonstration with NULL-able column added
CONSTRAINT Constraint_name DEFAULT 0 WITH VALUES
ALTER TABLE <table name>
ADD <new column name> <data type> NOT NULL
GO
ALTER TABLE <table name>
ADD CONSTRAINT <constraint name> DEFAULT <default value> FOR <new column name>
GO
ALTER TABLE MYTABLE ADD MYNEWCOLUMN VARCHAR(200) DEFAULT 'SNUGGLES'
The most basic version with two lines only
ALTER TABLE MyTable
ADD MyNewColumn INT NOT NULL DEFAULT 0
Beware when the column you are adding has a NOT NULL constraint, yet does not have a DEFAULT constraint (value). The ALTER TABLE statement will fail in that case if the table has any rows in it. The solution is to either remove the NOT NULL constraint from the new column, or provide a DEFAULT constraint for it.
Use:
-- Add a column with a default DateTime
-- to capture when each record is added.
ALTER TABLE myTableName
ADD RecordAddedDate SMALLDATETIME NULL DEFAULT (GETDATE())
GO
If you want to add multiple columns you can do it this way for example:
ALTER TABLE YourTable
ADD Column1 INT NOT NULL DEFAULT 0,
Column2 INT NOT NULL DEFAULT 1,
Column3 VARCHAR(50) DEFAULT 'Hello'
GO
To add a column to an existing database table with a default value, we can use:
ALTER TABLE [dbo.table_name]
ADD [Column_Name] BIT NOT NULL
Default ( 0 )
Here is another way to add a column to an existing database table with a default value.
A much more thorough SQL script to add a column with a default value is below including checking if the column exists before adding it also checkin the constraint and dropping it if there is one. This script also names the constraint so we can have a nice naming convention (I like DF_) and if not SQL will give us a constraint with a name which has a randomly generated number; so it's nice to be able to name the constraint too.
-------------------------------------------------------------------------
-- Drop COLUMN
-- Name of Column: Column_EmployeeName
-- Name of Table: table_Emplyee
--------------------------------------------------------------------------
IF EXISTS (
SELECT 1
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'table_Emplyee'
AND COLUMN_NAME = 'Column_EmployeeName'
)
BEGIN
IF EXISTS ( SELECT 1
FROM sys.default_constraints
WHERE object_id = OBJECT_ID('[dbo].[DF_table_Emplyee_Column_EmployeeName]')
AND parent_object_id = OBJECT_ID('[dbo].[table_Emplyee]')
)
BEGIN
------ DROP Contraint
ALTER TABLE [dbo].[table_Emplyee] DROP CONSTRAINT [DF_table_Emplyee_Column_EmployeeName]
PRINT '[DF_table_Emplyee_Column_EmployeeName] was dropped'
END
-- ----- DROP Column -----------------------------------------------------------------
ALTER TABLE [dbo].table_Emplyee
DROP COLUMN Column_EmployeeName
PRINT 'Column Column_EmployeeName in images table was dropped'
END
--------------------------------------------------------------------------
-- ADD COLUMN Column_EmployeeName IN table_Emplyee table
--------------------------------------------------------------------------
IF NOT EXISTS (
SELECT 1
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'table_Emplyee'
AND COLUMN_NAME = 'Column_EmployeeName'
)
BEGIN
----- ADD Column & Contraint
ALTER TABLE dbo.table_Emplyee
ADD Column_EmployeeName BIT NOT NULL
CONSTRAINT [DF_table_Emplyee_Column_EmployeeName] DEFAULT (0)
PRINT 'Column [DF_table_Emplyee_Column_EmployeeName] in table_Emplyee table was Added'
PRINT 'Contraint [DF_table_Emplyee_Column_EmployeeName] was Added'
END
GO
These are two ways to add a column to an existing database table with a default value.
Use:
ALTER TABLE {TABLENAME}
ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL}
CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
Reference: ALTER TABLE (Transact-SQL) (MSDN)
You can do the thing with T-SQL in the following way.
ALTER TABLE {TABLENAME}
ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL}
CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
As well as you can use SQL Server Management Studio also by right clicking table in the Design menu, setting the default value to table.
And furthermore, if you want to add the same column (if it does not exists) to all tables in database, then use:
USE AdventureWorks;
EXEC sp_msforeachtable
'PRINT ''ALTER TABLE ? ADD Date_Created DATETIME DEFAULT GETDATE();''' ;
In SQL Server 2008-R2, I go to the design mode - in a test database - and add my two columns using the designer and made the settings with the GUI, and then the infamous Right-Click gives the option "Generate Change Script"!
Bang up pops a little window with, you guessed it, the properly formatted guaranteed-to-work change script. Hit the easy button.
Alternatively, you can add a default without having to explicitly name the constraint:
ALTER TABLE [schema].[tablename] ADD DEFAULT ((0)) FOR [columnname]
If you have an issue with existing default constraints when creating this constraint then they can be removed by:
alter table [schema].[tablename] drop constraint [constraintname]
This can be done in the SSMS GUI as well. I show a default date below but the default value can be whatever, of course.
Put your table in design view (Right click on the table in object
explorer->Design)
Add a column to the table (or click on the column you want to update if
it already exists)
In Column Properties below, enter (getdate()) or 'abc' or 0 or whatever value you want in Default Value or Binding field as pictured below:
ALTER TABLE ADD ColumnName {Column_Type} Constraint
The MSDN article ALTER TABLE (Transact-SQL) has all of the alter table syntax.
Example:
ALTER TABLE [Employees] ADD Seniority int not null default 0 GO
Example:
ALTER TABLE tes
ADD ssd NUMBER DEFAULT '0';
First create a table with name student:
CREATE TABLE STUDENT (STUDENT_ID INT NOT NULL)
Add one column to it:
ALTER TABLE STUDENT
ADD STUDENT_NAME INT NOT NULL DEFAULT(0)
SELECT *
FROM STUDENT
The table is created and a column is added to an existing table with a default value.
This is for SQL Server:
ALTER TABLE TableName
ADD ColumnName (type) -- NULL OR NOT NULL
DEFAULT (default value)
WITH VALUES
Example:
ALTER TABLE Activities
ADD status int NOT NULL DEFAULT (0)
WITH VALUES
If you want to add constraints then:
ALTER TABLE Table_1
ADD row3 int NOT NULL
CONSTRAINT CONSTRAINT_NAME DEFAULT (0)
WITH VALUES
This has a lot of answers, but I feel the need to add this extended method. This seems a lot longer, but it is extremely useful if you're adding a NOT NULL field to a table with millions of rows in an active database.
ALTER TABLE {schemaName}.{tableName}
ADD {columnName} {datatype} NULL
CONSTRAINT {constraintName} DEFAULT {DefaultValue}
UPDATE {schemaName}.{tableName}
SET {columnName} = {DefaultValue}
WHERE {columName} IS NULL
ALTER TABLE {schemaName}.{tableName}
ALTER COLUMN {columnName} {datatype} NOT NULL
What this will do is add the column as a nullable field and with the default value, update all fields to the default value (or you can assign more meaningful values), and finally it will change the column to be NOT NULL.
The reason for this is if you update a large scale table and add a new not null field it has to write to every single row and hereby will lock out the entire table as it adds the column and then writes all the values.
This method will add the nullable column which operates a lot faster by itself, then fills the data before setting the not null status.
I've found that doing the entire thing in one statement will lock out one of our more active tables for 4-8 minutes and quite often I have killed the process. This method each part usually takes only a few seconds and causes minimal locking.
Additionally, if you have a table in the area of billions of rows it may be worth batching the update like so:
WHILE 1=1
BEGIN
UPDATE TOP (1000000) {schemaName}.{tableName}
SET {columnName} = {DefaultValue}
WHERE {columName} IS NULL
IF ##ROWCOUNT < 1000000
BREAK;
END
Try this
ALTER TABLE Product
ADD ProductID INT NOT NULL DEFAULT(1)
GO
SQL Server + Alter Table + Add Column + Default Value uniqueidentifier
ALTER TABLE Product
ADD ReferenceID uniqueidentifier not null
default (cast(cast(0 as binary) as uniqueidentifier))
--Adding Value with Default Value
ALTER TABLE TestTable
ADD ThirdCol INT NOT NULL DEFAULT(0)
GO
IF NOT EXISTS (
SELECT * FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME ='TABLENAME' AND COLUMN_NAME = 'COLUMNNAME'
)
BEGIN
ALTER TABLE TABLENAME ADD COLUMNNAME Nvarchar(MAX) Not Null default
END
Add a new column to a table:
ALTER TABLE [table]
ADD Column1 Datatype
For example,
ALTER TABLE [test]
ADD ID Int
If the user wants to make it auto incremented then:
ALTER TABLE [test]
ADD ID Int IDENTITY(1,1) NOT NULL
Try with the below query:
ALTER TABLE MyTable
ADD MyNewColumn DataType DEFAULT DefaultValue
This will add a new column into the Table.
This can be done by the below code.
CREATE TABLE TestTable
(FirstCol INT NOT NULL)
GO
------------------------------
-- Option 1
------------------------------
-- Adding New Column
ALTER TABLE TestTable
ADD SecondCol INT
GO
-- Updating it with Default
UPDATE TestTable
SET SecondCol = 0
GO
-- Alter
ALTER TABLE TestTable
ALTER COLUMN SecondCol INT NOT NULL
GO
There are 2 different ways to address this problem.
Both adds a default value but adds a totally different meaning to the problem statement here.
Lets start with creating some sample data.
Create Sample Data
CREATE TABLE ExistingTable (ID INT)
GO
INSERT INTO ExistingTable (ID)
VALUES (1), (2), (3)
GO
SELECT *
FROM ExistingTable
1.Add Columns with Default Value for Future Inserts
ALTER TABLE ExistingTable
ADD ColWithDefault VARCHAR(10) DEFAULT 'Hi'
GO
So now as we have added a default column when we are inserting a new record it will default it's value to 'Hi' if value not provided
INSERT INTO ExistingTable(ID)
VALUES (4)
GO
Select * from ExistingTable
GO
Well this addresses our problem to have default value but here is a catch to the problem.
What if we want to have default value in all the columns not just the future inserts???
For this we have Method 2.
2.Add Column with Default Value for ALL Inserts
ALTER TABLE ExistingTable
ADD DefaultColWithVal VARCHAR(10) DEFAULT 'DefaultAll'
WITH VALUES
GO
Select * from ExistingTable
GO
The following script will add a new column with a default value in every possible scenario.
Hope it adds value to the question asked.
Thanks.
Well, I now have some modification to my previous answer. I have noticed that none of the answers mentioned IF NOT EXISTS. So I am going to provide a new solution of it as I have faced some problems altering the table.
IF NOT EXISTS (SELECT * FROM INFORMATION_SCHEMA.columns WHERE table_name = 'TaskSheet' AND column_name = 'IsBilledToClient')
BEGIN
ALTER TABLE dbo.TaskSheet ADD
IsBilledToClient bit NOT NULL DEFAULT ((1))
END
GO
Here TaskSheet is the particular table name and IsBilledToClient is the new column which you are going to insert and 1 the default value. That means in the new column what will be the value of the existing rows, therefore one will be set automatically there. However, you can change as you wish with the respect of the column type like I have used BIT, so I put in default value 1.
I suggest the above system, because I have faced a problem. So what is the problem? The problem is, if the IsBilledToClient column does exists in the table table then if you execute only the portion of the code given below you will see an error in the SQL server Query builder. But if it does not exist then for the first time there will be no error when executing.
ALTER TABLE {TABLENAME}
ADD {COLUMNNAME} {TYPE} {NULL|NOT NULL}
CONSTRAINT {CONSTRAINT_NAME} DEFAULT {DEFAULT_VALUE}
[WITH VALUES]