Tags » Primary Key

Your First Realm App

In this tutorial, you’re going to work on a to-do app that’s built on the Realm Database. This will be very useful as you learn the basics of create, read, update, and delete operations with Realm. 2,197 more words


How to fetch the last ID from a MySQL Table and save it in a PHP Variable

When you are Involved in comparing and updating two different tables there may be times when you would need the last ID of a table so that it can be used in another table provided the ID is a primary key set to Auto Increment. 135 more words

Web Development

Constraints in Oracle

Create Primary Key

Method 1:

create table Employee
(Emp_id varchar2(10) primary key,
Ename varchar2(50),
Mobile numeric(10))

Method 2:

create table Employee
(Emp_id varchar2(10),
Ename varchar2(50),
Mobile numeric(10),
primary key(Emp_id))
… 281 more words

How to create a table in MYSQL that uses the same structure as an existing table?

There maybe times when you need to create a new table that uses the same structure as an existing table. I had this situation today, where I was working on a Test table in a database and then I needed to create a new table that would be used in production. 143 more words


Natural keys as Primary keys

Any Database designer looking at the post title would cringe. So would I for the next time. This post is a walk through of an example why it is a horrendous idea to do the above. 739 more words


Designing Tables with Integer Keys

While the “natural” key for a table is often a relatively stable string, better database designs leave the natural string keys as table columns/attributes and use integer “tag” values not containing any real world data for primary keys and foreign key relationships.    811 more words

Practical DBA


Explicación gráfica de las restricciones en SQL

Instrucciones Transact-SQL