 	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)
 );
 

/**
@table study

@desc This table contains details of some published studies. Most commonly the studies
      information comes from the DGVa or EGA sources.

@column study_id		Primary key, internal identifier.
@column source_id		Foreign key references to the 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 study				The pubmed/id or project name associated with this study.

@see source
@see variation_annotation

@column variation_annotation_id					Primary key, internal identifier.
@column variation_id										Foreign key references to the @link variation table.
@column phenotype_id										Foreign key references to the @link phenotype table.
@column study_id												Foreign key references to the @link study table.
@column local_study_id									Foreign key references to the @link study table.
@column associated_gene									Common gene(s) name(s) associated to the variation.
@column associated_variant_risk_allele	Allele associated to the phenotype.
