wording for 38.6.2.4. Simple CASE and 38.6.2.5. Searched CASE
От | Andreas Wenk |
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Тема | wording for 38.6.2.4. Simple CASE and 38.6.2.5. Searched CASE |
Дата | |
Msg-id | 4A85D211.8000604@netzmeister-st-pauli.de обсуждение исходный текст |
Ответы |
Re: wording for 38.6.2.4. Simple CASE and 38.6.2.5. Searched CASE
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Список | pgsql-docs |
Hi, I find it a little confusing how 38.6.2.4. Simple CASE and 38.6.2.5. Searched CASE is described. In Simple CASE is written CASE search-expression WHEN expression [, and in 38.6.2.5. Searched CASE is written CASE WHEN boolean-expression IMO speaking of a search-expression for the simple CASE and speaking of a boolean-expression in between Searched Case is confusing because of the use of the word "search". I would change it to that: [snip] 38.6.2.4. Simple CASE CASE WHEN boolean-expression THEN statements [ WHEN boolean-expression THEN statements ... ] [ ELSE statements ] END CASE; The simple form of CASE provides conditional execution based on truth of boolean expressions. Each WHEN clause's boolean-expression is evaluated in turn, until one is found that yields true. Then the corresponding statements are executed, and then control passes to the next statement after END CASE. (Subsequent WHEN expressions are not evaluated.) If no true result is found, the ELSE statements are executed; but if ELSE is not present, then a CASE_NOT_FOUND exception is raised. [EXAMPLE ...] 38.6.2.5. Searched CASE CASE search-expression WHEN expression [, expression [ ... ]] THEN statements [ WHEN expression [, expression [ ... ]] THEN statements ... ] [ ELSE statements ] END CASE; The searched form of CASE provides conditional execution based on equality of operands. The search-expression is evaluated (once) and successively compared to each expression in the WHEN clauses. If a match is found, then the corresponding statements are executed, and then control passes to the next statement after END CASE. (Subsequent WHEN expressions are not evaluated.) If no match is found, the ELSE statements are executed; but if ELSE is not present, then a CASE_NOT_FOUND exception is raised. [EXAMPLE ...] [snip] I moved 38.6.2.5 to 38.6.2.4 and changed the naming ... Thoughts? Cheers Andy
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