mysql set field unique
ALTER TABLE mytbl ADD UNIQUE (columnName);mysql set field unique
ALTER TABLE mytbl ADD UNIQUE (columnName);mysql alter table set column unique
ALTER TABLE contacts
ADD CONSTRAINT contacts_unique UNIQUE (reference_number);mysql create unique key via alter table
ALTER TABLE Persons
ADD CONSTRAINT UC_Person UNIQUE (ID,LastName);sql unique
This constraint ensures all values in a column are unique.
Example 1 (MySQL): Adds a unique constraint to the id column when
creating a new users table.
CREATE TABLE users (
id int NOT NULL,
name varchar(255) NOT NULL,
UNIQUE (id)
);
Example 2 (MySQL): Alters an existing column to add a UNIQUE
constraint.
ALTER TABLE users
ADD UNIQUE (id);Copyright © 2021 Codeinu
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