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Posted to codereview@trafodion.apache.org by traflm <gi...@git.apache.org> on 2016/12/11 09:05:01 UTC
[GitHub] incubator-trafodion pull request #875: [TRAFODION-2379] update sql reference...
GitHub user traflm opened a pull request:
https://github.com/apache/incubator-trafodion/pull/875
[TRAFODION-2379] update sql reference manual about group_concat function
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/traflm/incubator-trafodion TRAFODION-2379
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/incubator-trafodion/pull/875.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #875
----
commit b82c05b2ea9ca454c5abcccb6c4efa81b5221d52
Author: Liu Ming <ov...@sina.com>
Date: 2016-12-11T09:01:09Z
[TRAFODION-2379] update sql reference manual about group_concat function
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[GitHub] incubator-trafodion pull request #875: [TRAFODION-2379] update sql reference...
Posted by traflm <gi...@git.apache.org>.
Github user traflm commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/875#discussion_r92414734
--- Diff: docs/sql_reference/src/asciidoc/_chapters/sql_functions_and_expressions.adoc ---
@@ -3584,6 +3586,47 @@ Start/Date Time/Shipped (EXPR)
```
<<<
+[[group_concat_function]]
+== GROUP_CONCAT Function
+
+This function returns a string result with the concatenated non-NULL values from a group.
+It returns NULL if there are no non-NULL values.
+The syntax is as follows:
+
+```
+GROUP_CONCAT([DISTINCT] expr [,expr ...]
+ [ORDER BY {unsigned_integer | col_name | expr}
+ [ASC | DESC] [,col_name ...]]
+ [SEPARATOR str_val])
+```
+
+Get the concatenated values of expression combinations. To eliminate duplicate values,
+use the DISTINCT clause.
+To sort values in the result, use the ORDER BY clause. To sort in reverse order, add
+the DESC (descending) keyword to the name of the column you are sorting by in the
+ORDER BY clause. The default is ascending order; this may be specified explicitly using
+the ASC keyword. The default separator between values in a group is comma (,). To specify
+a separator explicitly, use SEPARATOR followed by the string literal value that should be
+inserted between group values. To eliminate the separator altogether, specify SEPARATOR ''.
+
+[[examples_of_group_concat]]
+=== Examples of GROUP_CONCAT
+
+The following example returns concatenated strings for column test_score for each student.
+
+```
+>> SELECT student_name,
+ GROUP_CONCAT(DISTINCT test_score
+ ORDER BY test_score DESC SEPARATOR ' ')
+ FROM student
+ GROUP BY student_name;
+STUDENT_NAME (EXPR)
+-------------- --------------
+scott 80 90 91 56
+tom 77 43 91
--- End diff --
Thanks Dave, it should be ordered, I will update the text.
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[GitHub] incubator-trafodion pull request #875: [TRAFODION-2379] update sql reference...
Posted by DaveBirdsall <gi...@git.apache.org>.
Github user DaveBirdsall commented on a diff in the pull request:
https://github.com/apache/incubator-trafodion/pull/875#discussion_r92278930
--- Diff: docs/sql_reference/src/asciidoc/_chapters/sql_functions_and_expressions.adoc ---
@@ -3584,6 +3586,47 @@ Start/Date Time/Shipped (EXPR)
```
<<<
+[[group_concat_function]]
+== GROUP_CONCAT Function
+
+This function returns a string result with the concatenated non-NULL values from a group.
+It returns NULL if there are no non-NULL values.
+The syntax is as follows:
+
+```
+GROUP_CONCAT([DISTINCT] expr [,expr ...]
+ [ORDER BY {unsigned_integer | col_name | expr}
+ [ASC | DESC] [,col_name ...]]
+ [SEPARATOR str_val])
+```
+
+Get the concatenated values of expression combinations. To eliminate duplicate values,
+use the DISTINCT clause.
+To sort values in the result, use the ORDER BY clause. To sort in reverse order, add
+the DESC (descending) keyword to the name of the column you are sorting by in the
+ORDER BY clause. The default is ascending order; this may be specified explicitly using
+the ASC keyword. The default separator between values in a group is comma (,). To specify
+a separator explicitly, use SEPARATOR followed by the string literal value that should be
+inserted between group values. To eliminate the separator altogether, specify SEPARATOR ''.
+
+[[examples_of_group_concat]]
+=== Examples of GROUP_CONCAT
+
+The following example returns concatenated strings for column test_score for each student.
+
+```
+>> SELECT student_name,
+ GROUP_CONCAT(DISTINCT test_score
+ ORDER BY test_score DESC SEPARATOR ' ')
+ FROM student
+ GROUP BY student_name;
+STUDENT_NAME (EXPR)
+-------------- --------------
+scott 80 90 91 56
+tom 77 43 91
--- End diff --
The test scores aren't in order. When I tried this example, I got "91 90 80 56" for scott's test scores, and "91 77 43" for tom's. So the code seems to work. Just this text seems to be wrong.
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[GitHub] incubator-trafodion pull request #875: [TRAFODION-2379] update sql reference...
Posted by asfgit <gi...@git.apache.org>.
Github user asfgit closed the pull request at:
https://github.com/apache/incubator-trafodion/pull/875
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