Sql

Search

difference between primary key and unique key

Primary Key: 
1. Primary Key is used to identify all the records in a relation uniquely.
2. Primary key can not have null value.
3. Primary key can be only one per table.
4. Primary key creats clustered index.

Unique key: 
1. Unique key is also used to identify a records uniquely.
2. Unique key can accept one null value.
3. Unique key can be multiple in a table.
4. Unique key creates non-clustered index.

Comment

PREVIOUS	NEXT

Code Example
Sql :: Cast for print sql
Sql :: postgres select duplicate columns
Sql :: date format mysql
Sql :: index column size too large. the maximum column size is 767 bytes. mysql
Sql :: how to query date in sql server
Sql :: mysql check date range
Sql :: empty table sqlite
Sql :: output table plsql
Sql :: ERROR 1046 (3D000): No database selected
Sql :: oracle drop job if exists
Sql :: check database size in gb mysql
Sql :: postgresql subtract date/hours
Sql :: mysql regexp match word
Sql :: count in sql and diff
Sql :: postgres update multiple columns
Sql :: sql select count distinct
Sql :: mysql remove auto increment
Sql :: sql order by alphabetical
Sql :: if column value is null then in mysql
Sql :: commit in sql
Sql :: mysql date format
Sql :: sql database connectivity
Sql :: pagination in sql
Sql :: sql alter table order by
Sql :: df to sql pandas sql achemy
Sql :: postgres trigger insert into another table
Sql :: mysql auto increment column
Sql :: insert into auto increment mysql
Sql :: create empty table from existing table
Sql :: there is no unique constraint matching given keys for referenced table

Search

SQL

difference between primary key and unique key

ADD CONTENT