What is the species with the common name "mouse"?
CREATE TABLE "homologs" (
  "species" text,
  "species_common_name" text,
  "ncbi_accession_number_m_rna_protein" text,
  "length_bp_aa" text,
  "protein_identity" text
);
SELECT COUNT("species") FROM "homologs" WHERE "species_common_name"='Mouse';