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49 lines
2.3 KiB
Markdown
49 lines
2.3 KiB
Markdown
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\<query> ::=
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`[WITH <alias> AS ( <query> ) [, <alias> AS ( <query> ) ] [ ,...n ] ]`
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`FROM { <table-view> [ <alias> ]`
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` [ { JOIN | LEFT JOIN | RIGHT JOIN | OUTER JOIN }`
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` <table-view> [ <alias> ]`
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` ON <predicate>`
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` ]
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` } [ ,...n ]`
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`[ WHERE <predicate> ]`
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`SELECT { [ { <table-view>. | <alias> }. ] *`
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` | { <column-expression> | <column-alias> } [ ,...n ]`
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`[ GROUP BY { <column-expression> | <column-alias> } [ ,...n ] ]`
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`[ HAVING <predicate> ]`
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`[ INTO <new-table> ]`
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`[ ORDER BY { <column-expression> | <column-alias> } [ ,...n ] ]`
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`[ { UNION | UNION ALL | EXCEPT | INTERSECT } <query> ] [ ...n ]`
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`<table-view> ::=`
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`[ <database-name>.<namespace-name> | <database-name>.. | <namespace-name>. ]`
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`{ <view-name> | <table-name> }`
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`<column-expression> ::=`
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{ [ { <alias>. | <qualified-or-not-table-or-view-name>. } ] <column-name>`
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` | <constant> | <expression> }
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`<predicate> ::=`
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`{ <column-expression> | <column-alias> }`
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`{ { = | <> | <= | =< | < | >= | => | > | }`
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` { <column-expression> | <column-alias> } }`
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`| [ NOT ] IN ( <constant> [ ,...n ] | <query-single-column-result> )`
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`| [ NOT ] BETWEEN { <column-expression> | <column-alias> }`
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` AND { <column-expression> | <column-alias> }`
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`[ { AND | OR } [ ,...n ] ]`
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`<expression> ::=`
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`IF <predicate> THEN <column-expression> ENDIF`
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`| CASE <column-expression>`
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` WHEN { <predicate> | <column-expression> } THEN <column-expression> [ ...n ]`
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` [ ELSE <column-expression> ]`
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` END`
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`| COALESCE ( <column-expression> [ ,...n ] )`
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`| native hoon (stretch goal)`
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Discussion:
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Set operators apply the previous result set to the next query unless otherwise qualified by parentheses.
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`ORDER BY` is not allowed in Common Table Experessions (CTE, WITH clause) or in any query joined by set operators except for the last of the queries.
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`SELECT INTO` targets an existing table not otherwise in the query.
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`COALESCE` returns the first `<column-expression>` in the list that does not evaluate to `~` (in the case of unit) or not in the selected `<column-expression>` due to `LEFT` or `RIGHT JOIN`.
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If a `CASE WHEN` expression is a `<predicate>`, the expected boolean (or loobean) logic applies. If it is a <column-expression> atom value 0 is treated as false and any other value as true (not loobean).
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