make column not null sql code example

Example 1: Change A filed to not null

ALTER TABLE
  clients
ALTER COLUMN
  phone
    NVARCHAR(20) NOT NULL;

Example 2: change sql column from null to not null

ALTER TABLE [TABLE_NAME] CHANGE [COLUMN_NAME] [COLUMN_NAME] [COLUMN_TYPE] NOT NULL DEFAULT [DEFAULT];

Example 3: add new column not null sql server

ALTER TABLE MY_TABLE
ADD STAGE INT NOT NULL
DEFAULT '0';