From: Matt S Trout Date: Tue, 1 Oct 2019 19:46:30 +0000 (+0000) Subject: document the from and using clauses added to update and delete X-Git-Tag: v1.90_01~23 X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=49dba492babc1248fa1acbf75f1bfd237f2a6ef3;p=dbsrgits%2FSQL-Abstract.git document the from and using clauses added to update and delete --- diff --git a/lib/SQL/Abstract/ExtraClauses.pm b/lib/SQL/Abstract/ExtraClauses.pm index 4ce6c52..7d576bf 100644 --- a/lib/SQL/Abstract/ExtraClauses.pm +++ b/lib/SQL/Abstract/ExtraClauses.pm @@ -727,4 +727,82 @@ gathered together and moved into an inner select node: ORDER BY baz [ 1, 1 ] +=head2 update from clause + +Some databases allow an additional FROM clause to reference other tables +for the data to update; this clause is expanded as a normal from list, check +your database for what is and isn't allowed in practice. + + # expr + { -update => { + _ => 'employees', + from => 'accounts', + set => { sales_count => { sales_count => { '+' => \1 } } }, + where => { + 'accounts.name' => { '=' => \"'Acme Corporation'" }, + 'employees.id' => { -ident => 'accounts.sales_person' }, + }, + } } + + # aqt + { -update => { + from => { -ident => [ 'accounts' ] }, + set => { -op => [ + ',', { -op => [ + '=', { -ident => [ 'sales_count' ] }, { -op => [ + '+', { -ident => [ 'sales_count' ] }, + { -literal => [ 1 ] }, + ] }, + ] }, + ] }, + target => { -ident => [ 'employees' ] }, + where => { -op => [ + 'and', { -op => [ + '=', { -ident => [ 'accounts', 'name' ] }, + { -literal => [ "'Acme Corporation'" ] }, + ] }, { -op => [ + '=', { -ident => [ 'employees', 'id' ] }, + { -ident => [ 'accounts', 'sales_person' ] }, + ] }, + ] }, + } } + + # query + UPDATE employees SET sales_count = sales_count + 1 FROM accounts + WHERE ( + accounts.name = 'Acme Corporation' + AND employees.id = accounts.sales_person + ) + + [] + + [] + +=head2 delete using clause + +Some databases allow an additional USING clause to reference other tables +for the data to update; this clause is expanded as a normal from list, check +your database for what is and isn't allowed in practice. + + # expr + { -delete => { + from => 'x', + using => 'y', + where => { 'x.id' => { -ident => 'y.x_id' } }, + } } + + # aqt + { -delete => { + target => { -op => [ ',', { -ident => [ 'x' ] } ] }, + using => { -ident => [ 'y' ] }, + where => { -op => [ + '=', { -ident => [ 'x', 'id' ] }, + { -ident => [ 'y', 'x_id' ] }, + ] }, + } } + + # query + DELETE FROM x USING y WHERE x.id = y.x_id + [] + =cut