GOAL
I would like to add a Redshift SUPER column to and existing redshift table.
I need this to store JSON data there
CODE
This is how Normally I would add a new column.
ALTER TABLE products
ADD COLUMN created_at NOT NULL;
1. Tried
CREATE TABLE temp_test_persons (
PersonID int,
LastName varchar(255),
FirstName varchar(255),
Address varchar(255),
City varchar(255)
);
ALTER TABLE temp_test_persons ADD COLUMN newSuperColumn SUPER NOT NULL;
Error running query: ALTER TABLE ADD COLUMN defined as NOT NULL must have a non-null default expression
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The solution is to set a default value for the column. Then you can define the column as NotNull.
Like this
ALTER TABLE temp_test_persons
ADD COLUMN newSuperColumn SUPER NOT NULL
DEFAULT '';
ALTER TABLE temp_test_persons
ADD COLUMN newSuperColumn SUPER;
Related
Is it possible to add multiple columns in a single Alter query in Redshift
Alter table employee
add column Name,
add column Age,
add column Salary
According to Redshift Documentation, You can add only one column in each ALTER TABLE statement. Only way to add multiple columns is executing multiple ALTER TABLE statements.
Could someone explain why in the below statements one is valid and the other isn't when they appear identical (ignoring the fact one is a CREATE and the other an ALTER).
"ALTER TABLE only allows columns to be added that can contain nulls, or have a DEFAULT definition specified", why does CREATE TABLE allow for null columns to be added that don't have a default value specified?
CREATE TABLE Test
(
ID int NOT NULL
);
ALTER TABLE Test ADD
ID int NOT NULL;
Say that a table contains 2 rows of data.
This statement:
ALTER TABLE Test ADD ID int NOT NULL;
(if it could execute) would create a new column and the 2 existing rows would have an id = NULL although you defined the column as NOT NULL!!!
Do you see the problem?
But for the CREATE statement there is not such a problem because at the time of the creation there is no data.
Your version of the query doesn't work because the table already has a column called id. You cannot add another one.
But, you can add a new column, so this will work:
ALTER TABLE Test ADD ID2 int NOT NULL;
Or rather, this works on an empty table. You cannot add a NOT NULL column with no DEFAULT to a table with any rows. The existing rows will get the column. But with what value? It can't be NULL because of the NOT NULL constraint. And there is no alternative DEFAULT value.
I need a SQL query which adds a new column after an existing column, so the column will be added in a specific order.
ALTER TABLE table_name ADD COLUMN MiddleName varchar(50) AFTER Gender.
You have two options. First, you could simply add a new column with the following:
ALTER TABLE {tableName} ADD COLUMN COLNew {type};
Second, and more complicatedly, but would actually put the column where you want it, would be to rename the table:
ALTER TABLE {tableName} RENAME TO TempOldTable;
Hope it helped.
I'm new to SQL. I created a table and filled it with some data. Now I want to change the properties of my primary key, so it will auto increment every single time by itself when adding data.
I know how to do it when creating a table, but where do I add auto_increment now, when I already have a created table with filled data?
Update
Try
ALTER TABLE [TableName] DROP COLUMN ID
ALTER TABLE [TableName] ADD ID INT IDENTITY(1,1)
If you had entered data to your table review this link that have an answer to you question SQL Server, How to set auto increment after creating a table without data loss?
You can't change logical structure column when you have some filled data in column. That's impossible. You must deleting data from column and use ALTER TABLE to change properites column
I have a sybase db table in which i need to add a new column.
The conditions: The column must not allow nulls and be unique.
what is the alter table sql to achieve this?
EDIT:
It is a varchar type column.Yes the table as of now is empty, but when filled it is ensured that unique values would be filled in.
I tired executing
alter table Test add Name varchar not null unique
i get error saying default value must be specified as not null is given.
but i want to add unique constraint so do i really need to specify default?
thanks
Unique values are specified as part of an index on the column, not in the column definition itself.
Try:
alter table Test add Name varchar not null
create unique index index_name_unique on Test (Name)
The ASE reference manual can help with more detail.
Once a table has been created Sybase ASE does not allow addition of NOT NULL column directly unless a default is specified for the column. However, if the table is still empty you can do the following -
First add the new column as a NULL column to the table using alter table command -
alter table Test add Name varchar(100) null
Once this has been done, try modifying the same column Name in the table Test using the alter table script -
alter table Test modify Name varchar(100) NOT NULL
and you will see that you are able to modify the Name column to a NOT NULL column using these steps. This is because at this time Sybase server checks as there is no data in the table hence the NOT NULL constraint is not checked and the column is made NOT NULL. Hence, we are able to skip the default constraint.
In case there would have been some data already present in the table Test, then we need to add one more step in between steps 1 and 2 which will add default values to the existing rows in the table. This can be done via a script for previous data and then following the step 2.
To make the column only allow unique values for the column you need to add a unique key constraint using the following syntax -
alter table Test add constraint UK1 unique(Name)