id,page,ref,title,content,breadcrumbs,references
sql_queries:sql-parameters,sql_queries,sql-parameters,Named parameters,"Datasette has special support for SQLite named parameters. Consider a SQL query like this: 
             select * from Street_Tree_List
where ""PermitNotes"" like :notes
and ""qSpecies"" = :species 
             If you execute this query using the custom query editor, Datasette will extract the two named parameters and use them to construct form fields for you to provide values. 
             You can also provide values for these fields by constructing a URL: 
             /mydatabase?sql=select...&species=44 
             SQLite string escaping rules will be applied to values passed using named parameters - they will be wrapped in quotes and their content will be correctly escaped. 
             Values from named parameters are treated as SQLite strings. If you need to perform numeric comparisons on them you should cast them to an integer or float first using  cast(:name as integer)  or  cast(:name as real) , for example: 
             select * from Street_Tree_List
where latitude > cast(:min_latitude as real)
and latitude < cast(:max_latitude as real) 
             Datasette disallows custom SQL queries containing the string PRAGMA (with a small number  of exceptions ) as SQLite pragma statements can be used to change database settings at runtime. If you need to include the string ""pragma"" in a query you can do so safely using a named parameter.","[""Running SQL queries""]","[{""href"": ""https://github.com/simonw/datasette/issues/761"", ""label"": ""of exceptions""}]"
sql_queries:id3,sql_queries,id3,Cross-database queries,"SQLite has the ability to run queries that join across multiple databases. Up to ten databases can be attached to a single SQLite connection and queried together. 
             Datasette can execute joins across multiple databases if it is started with the  --crossdb  option: 
             datasette fixtures.db extra_database.db --crossdb 
             If it is started in this way, the  /_memory  page can be used to execute queries that join across multiple databases. 
             References to tables in attached databases should be preceded by the database name and a period. 
             For example, this query will show a list of tables across both of the above databases: 
             select
  'fixtures' as database, *
from
  [fixtures].sqlite_master
union
select
  'extra_database' as database, *
from
  [extra_database].sqlite_master 
             Try that out here .","[""Running SQL queries""]","[{""href"": ""https://latest.datasette.io/_memory?sql=select%0D%0A++%27fixtures%27+as+database%2C+*%0D%0Afrom%0D%0A++%5Bfixtures%5D.sqlite_master%0D%0Aunion%0D%0Aselect%0D%0A++%27extra_database%27+as+database%2C+*%0D%0Afrom%0D%0A++%5Bextra_database%5D.sqlite_master"", ""label"": ""Try that out here""}]"
sql_queries:canned-queries-named-parameters,sql_queries,canned-queries-named-parameters,Canned query parameters,"Canned queries support named parameters, so if you include those in the SQL you will then be able to enter them using the form fields on the canned query page or by adding them to the URL. This means canned queries can be used to create custom JSON APIs based on a carefully designed SQL statement. 
                 Here's an example of a canned query with a named parameter: 
                 select neighborhood, facet_cities.name, state
from facetable
  join facet_cities on facetable.city_id = facet_cities.id
where neighborhood like '%' || :text || '%'
order by neighborhood; 
                 In the canned query configuration looks like this: 
                 [[[cog
config_example(cog, """"""
databases:
  fixtures:
    queries:
      neighborhood_search:
        title: Search neighborhoods
        sql: |-
          select neighborhood, facet_cities.name, state
          from facetable
            join facet_cities on facetable.city_id = facet_cities.id
          where neighborhood like '%' || :text || '%'
          order by neighborhood
"""""") 
                 ]]] 
                 [[[end]]] 
                 Note that we are using SQLite string concatenation here - the  ||  operator - to add wildcard  %  characters to the string provided by the user. 
                 You can try this canned query out here:
                     https://latest.datasette.io/fixtures/neighborhood_search?text=town 
                 In this example the  :text  named parameter is automatically extracted from the query using a regular expression. 
                 You can alternatively provide an explicit list of named parameters using the  ""params""  key, like this: 
                 [[[cog
config_example(cog, """"""
databases:
  fixtures:
    queries:
      neighborhood_search:
        title: Search neighborhoods
        params:
        - text
        sql: |-
          select neighborhood, facet_cities.name, state
          from facetable
            join facet_cities on facetable.city_id = facet_cities.id
          where neighborhood like '%' || :text || '%'
          order by neighborhood
"""""") 
                 ]]] 
                 [[[end]]]","[""Running SQL queries"", ""Canned queries""]","[{""href"": ""https://latest.datasette.io/fixtures/neighborhood_search?text=town"", ""label"": ""https://latest.datasette.io/fixtures/neighborhood_search?text=town""}]"
sql_queries:sql-views,sql_queries,sql-views,Views,"If you want to bundle some pre-written SQL queries with your Datasette-hosted database you can do so in two ways. The first is to include SQL views in your database - Datasette will then list those views on your database index page. 
             The quickest way to create views is with the SQLite command-line interface: 
             sqlite3 sf-trees.db 
             SQLite version 3.19.3 2017-06-27 16:48:08
Enter "".help"" for usage hints.
sqlite> CREATE VIEW demo_view AS select qSpecies from Street_Tree_List;
<CTRL+D> 
             You can also use the  sqlite-utils  tool to  create a view : 
             sqlite-utils create-view sf-trees.db demo_view ""select qSpecies from Street_Tree_List""","[""Running SQL queries""]","[{""href"": ""https://sqlite-utils.datasette.io/"", ""label"": ""sqlite-utils""}, {""href"": ""https://sqlite-utils.datasette.io/en/stable/cli.html#creating-views"", ""label"": ""create a view""}]"