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EGQuery: Provides Entrez database counts in XML for a single search using Global Query.
Utility parameters may be case sensitive, therefore, use lower case characters in all parameters except for WebEnv.
Base URL: http://eutils.ncbi.nlm.nih.gov/entrez/eutils/egquery.fcgi
Search Terms: This command uses search terms or phrases with or without Boolean operators or search term qualifications. See the PubMed Help or Entrez Help for information about available search term qualification.
term=search strategy
For example:
terms=stem+cells
Tool: A string with no internal spaces that identifies the resource which is using Entrez links (e.g., tool=flybase). This argument is used to help NCBI provide better service to third parties generating Entrez queries from programs. As with any query system, it is sometimes possible to ask the same question different ways, with different effects on performance. NCBI requests that developers sending batch requests include a constant 'tool' argument for all requests using the utilities.
tool=E-mail Address: If you choose to provide an email address, we will use it to contact you if there are problems with your queries or if we are changing software interfaces that might specifically affect your requests. If you choose not to include an email address we cannot provide specific help to you, but you can still sign up for utilities-announce to receive general announcements.
email=
Examples:
Display counts in XML for stem cells in each Entrez database:
http://eutils.ncbi.nlm.nih.gov/entrez/eutils/egquery.fcgi?term=stem+cells
Display counts in XML for brca1 or brca2 for each Entrez database:
http://eutils.ncbi.nlm.nih.gov/entrez/eutils/egquery.fcgi?term=brca1+OR+brca2