 	name varchar(255) not null,
 	description varchar(255) DEFAULT NULL,
 	url varchar(255) DEFAULT NULL,
-	study varchar(255) DEFAULT NULL,
+	external_reference varchar(255) DEFAULT NULL,
+	study_type set('GWAS'),
 	
 	primary key( study_id ),
-	unique key name_idx(name),
 	key source_idx (source_id)
 );
 

	variation_annotation_id int(10) unsigned not null auto_increment,
	variation_id int(10) unsigned not null,
	phenotype_id int(10) unsigned not null,
	source_id int(10) unsigned not null,
	study varchar(30) default NULL,
	study_type set('GWAS'),
	local_study_id int(10) default NULL,
	associated_gene varchar(255) default NULL,
	associated_variant_risk_allele varchar(255) default NULL,

/**
@table study

@desc This table contains details of the studies.
			The studies information can come from internal studies (DGVa, EGA) or from external studies (Uniprot, NHGRI, ...).

@column study_id						Primary key, internal identifier.
@column source_id						Foreign key references to the @link source table.
@column name								Name of the study. e.g. "EGAS00000000001"
@column description					Description of the study.
@column url									URL to find the study data (http or ftp).
@column external_reference	The pubmed/id or project name associated with this study.
@column study_type					Displays if a study comes from a genome-wide association study or not.

@see source
@see variation_annotation
