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https://issues.apache.org/jira/browse/TRAFODION-3306?focusedWorklogId=233227&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-233227
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ASF GitHub Bot logged work on TRAFODION-3306:
---------------------------------------------
Author: ASF GitHub Bot
Created on: 26/Apr/19 01:49
Start Date: 26/Apr/19 01:49
Worklog Time Spent: 10m
Work Description: liuyu000 commented on pull request #1837:
[TRAFODION-3306] Add the TRUNC Function in the Trafodion SQL Reference Manual
URL: https://github.com/apache/trafodion/pull/1837#discussion_r278786551
##########
File path:
docs/sql_reference/src/asciidoc/_chapters/sql_functions_and_expressions.adoc
##########
@@ -12460,6 +12460,122 @@ CHAR(20). This expression uses the TRIM function to
return the value
TRIM(first_name) || ' ' || TRIM (last_name)
```
+[[trunc_function]]
+== TRUNC Function
+
+The TRUNC (TRUNCATE) function truncates `_numeric-expression_` on an optional
`_decimal-place_` decimal position(s), that is, it rounds down
`_numeric-expression_` to the nearest (or equal) integer closer to zero
*without rounding*.
+
+TRUNC is a Trafodion SQL extension.
+
+`TRUNC (_numeric-expression_[, _decimal-place_])`
+
+[[syntax_descriptions_of_trunc]]
+=== Syntax Descriptions of TRUNC
+
+* `_numeric-expression_`
+
++
+is an SQL numeric expression to be truncated.
+
++
+For more information, see <<numeric_value_expressions,Numeric Value
Expressions>>.
+
+* `_decimal-place_`
+
++
+is an integer specifying the precision of the truncation.
+
+NOTE: `_numeric-expression_` and `_decimal-place_` cannot be NULL.
+
+NOTE: Currently, `_decimal-place_` can be zero or a positive integer, while
*negative integer* is *not supported*.
+
+NOTE: If `_decimal-place_` is omitted, `_numeric-expression_` is truncated to
zero decimal position, which means all digits after the decimal point are
removed.
+
+*Example*
+
+```
+SELECT TRUNC (-1.2345), TRUNC (1.2345) FROM DUAL
+
+(EXPR) (EXPR)
+----------- -----------
+
+ -1 1
+
+--- 1 row(s) selected.
+```
+
+NOTE: If `_decimal-place_` is a positive integer, `_numeric-expression_` is
truncated to `_decimal-place_` decimal position(s) to the right of the decimal
point. +
+*Example* +
+1 for truncating to a multiple of 0.1 +
+2 for truncating to a multiple of 0.01 +
+3 for truncating to a multiple of 0.001 +
+
+*Example*
+
+```
+SELECT TRUNC (1.2345,1), TRUNC (1.2345,2), TRUNC (1.2345, 3), TRUNC (1.2345,
4) FROM DUAL;
+
+(EXPR) (EXPR) (EXPR) (EXPR)
+------------ ------------ ------------ ------------
+
+ 1.2 1.23 1.234 1.2345
+
+--- 1 row(s) selected.
+```
+
+NOTE: `_decimal-place_` cannot be larger than the number of decimal digits.
+
+[[considerations_for_trunc]]
+=== Considerations for TRUNC
+
+* Trafodion provides the <<ceil_function, CEIL Function>>, the
<<floor_function, FLOOR Function>>, the <<round_function, ROUND Function>> and
the <<trunc_function, TRUNC Function>> to round numbers, these functions can be
interchanged in certain circumstances.
+
++
+*Example*
+
++
+|===
+
+^| *Condition* ^| *Result*
+
+| All of the following conditions for the TRUNC function are true： +
+ ◦ `_numeric-expression_` is *greater* than zero +
+ ◦ `_decimal-place_` is not specified
+
+| *TRUNC* function = *FLOOR* function
+
+| All of the following conditions for the TRUNC function are true： +
+ ◦ `_numeric-expression_` is *less* than zero +
+ ◦ `_decimal-place_` is not specified
+
+| *TRUNC* function = *CEIL* function
+
+|===
+
+* The TRUNC function is similar to the ROUND function in terms of *reducing
the number of decimal places*.
+
++
+However, the TRUNC function *does not perform any rounding* as the ROUND
function does.
Review comment:
Thank you, I've incorporated your comment.
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Issue Time Tracking
-------------------
Worklog Id: (was: 233227)
Time Spent: 1h 10m (was: 1h)
> Add the TRUNC Function in the Trafodion SQL Reference Manual
> ------------------------------------------------------------
>
> Key: TRAFODION-3306
> URL: https://issues.apache.org/jira/browse/TRAFODION-3306
> Project: Apache Trafodion
> Issue Type: Documentation
> Reporter: Liu Yu
> Priority: Major
> Fix For: 2.4
>
> Time Spent: 1h 10m
> Remaining Estimate: 0h
>
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