Thanks Julian. There are several sources that support the case of multi-char SC, including Sparks, Microsoft, as well as Calcite's own reference page. But I guess we only need to worry about the single-char case. ------------------------------------------------------------------发件人：Julian Hyde <[email protected]>发送时间：2017年12月7日(星期四) 18:26收件人：dev <[email protected]>主 题：Re: question about trim() function I take it you mean
trim(‘ab’ from ‘abcba') (Double-quotes delimit identifiers, not character literals.) SQL standard says: 6.30.11 If <trim function> is specified, then: (a) Let S be the value of the <trim source>. (b) If <trim character> is specified, then let SC be the value of <trim character>; otherwise, let SC be <space>. (c) If at least one of S and SC is the null value, then the result of the <trim function> is the null value. If the length in characters of SC is not 1 (one), then an exception condition is raised: data exception — trim error. <trim function> ::= TRIM <left paren> <trim operands> <right paren> <trim operands> ::= [ [ <trim specification> ] [ <trim character> ] FROM ] <trim source> <trim source> ::= <character value expression> <trim specification> ::= LEADING | TRAILING | BOTH In your example, Calclte should give an error because ‘ab’ does not have length 1. You’ll see a comment to that effect in SqlOperatorBaseTest.testTrimFunc (but sadly that part of the test is disabled). Julian > On Dec 7, 2017, at 1:59 AM, 于仲(重籽) <[email protected]> wrote: > > It seems that trim("ab" from "abcba")should return "c", according to >https://calcite.apache.org/docs/reference.html > However calcite removes only "a" of "ab", and this trim() returs "bcb". See >implementation of SqlFunctions.trim() > Is it a bug or something? :) > > Zhong Yu
