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From:Scott Purcell Date:April 3 2006 1:10pm
Subject:Syntax Question Constraint, Index
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I  ran into some syntax over the weekend, that I am trying to make sense
of. Here is the create table statements.

 

Drop table if exists events

Drop table if exists locations

 

Create table events (

uid BIGINT NOT NULL AUTO_INCREMENT,

name VARCHAR(255),

start_date DATE,

duration INTEGER,

location_id BIGINT,

primary key (uid)

);

 

Create table locations (

uid BIGINT NOT NULL AUTO_INCREMENT,

name VARCHAR(255),

address VARCHAR(255),

primary key (uid)

)

 

Alter table events add index (location_id), add

Constraint FKB307E11920EBB9E5 foreign key (location_id) references
locations(uid)

 

 

// Here is my conclusion, and I was hoping someone may back this up.

Events has  a primary key of UID that is auto_incremeneted.

Locations has a primary key of UID that is also incremented.

 

The constraint and index are where I have questions. What is the index
and constraint doing? I can't seem to get my mind around what that alter
statement is trying to accomplish.

 

Thanks,

 

 


Thread
Syntax Question Constraint, IndexScott Purcell3 Apr
  • Re: Syntax Question Constraint, IndexMartijn Tonies3 Apr