Not null key in mysql

They are the same. Yosef this is just a matter of style. Hammerite Hammerite Rob Rob See en. Sign up or log in Sign up using Google. Sign up using Facebook.

Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The primary key follows these rules:.

Because MySQL works faster with integers, the data type of the primary key column should be the integer e. And you should ensure sure that value ranges of the integer type for the primary key are sufficient for storing all possible rows that the table may have. The basic syntax when null is used as a keyword is as follows. Continuing with the example above , suppose we need details of members whose contact number is not null. We can execute a query like. Skip to content.

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Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 6 years, 3 months ago. Active 6 years, 3 months ago. Viewed 2k times. Improve this question. Jonathan Leffler k gold badges silver badges bronze badges. Your fields need defined before constraints using them. It is also highly unlikely the same field, especially one named id, should reference two other tables.