Modify table How to change Allow Nulls attribute from not null to allow null

Question

How to change one attribute in a table using T-SQL to allow nulls  not null --  null   Alter table maybe

User · Answer

For MySQL  MariaDB  ALTER TABLE  table name  MODIFY COLUMN  column name   data type  NULL   Use MODIFY COLUMN instead of ALTER COLUMN

User · Answer

-- replace NVARCHAR 42  with the actual type of your column ALTER TABLE your table ALTER COLUMN your column NVARCHAR 42  NULL

User · Answer

ALTER TABLE public contract termination requests ALTER COLUMN management company id DROP NOT NULL

User · Answer

Yes you can use ALTER TABLE as follows   ALTER TABLE  table name  ALTER COLUMN  column name   data type  NULL   Quoting from the ALTER TABLE documentation      NULL can be specified in ALTER COLUMN to force a NOT NULL column to allow null values  except for columns in PRIMARY KEY constraints

User · Answer

ALTER TABLE is right   ALTER TABLE MyCustomers ALTER COLUMN CompanyName VARCHAR 20  NULL

User · Answer

This is the approach to do this  -   Check whether the table or column exists or not  If yes  then alter the column  e g -   IF EXISTS  SELECT 1 FROM INFORMATION SCHEMA COLUMNS WHERE              TABLE CATALOG    DBName  AND              TABLE SCHEMA    SchemaName  AND             TABLE NAME    TableName  AND             COLUMN NAME    ColumnName   BEGIN     ALTER TABLE DBName SchemaName TableName ALTER COLUMN ColumnName  data type  NULL END     If you don t have any schema then delete the schema line because you don t need to give the default schema

User · Answer

I wrote this so I could edit all tables and columns to null at once   select  case when sc max length    -1  and st name in   char   decimal   nvarchar   varchar   then  alter table       so name      alter column      sc name          st name     MAX  NULL  when st name in   char   decimal   nvarchar   varchar   then  alter table       so name      alter column      sc name          st name         cast sc max length as varchar 4        NULL  else  alter table       so name      alter column      sc name          st name     NULL  end as query from sys columns sc inner join sys types st on st system type id   sc system type id inner join sys objects so on so object id   sc object id where so type    U  and st name  lt  gt   timestamp  order by st name

User · Answer

So the simplest way is    alter table table name change column name column name int 11  NULL

[sql] Modify table: How to change 'Allow Nulls' attribute from not null to allow null

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