How to SUBSTR a calculated row in SQL Query? - sql

Question

Original Query:
SELECT F4105.COUNCS/10000 FROM F4105
Output:
Numeric Expression
--------------------
111.1643000000000000
111.1633000000000000
111.1633000000000000
101.7654000000000000
101.7654000000000000
112.7258000000000000
I need to remove at least the last 5 zeroes. I tried to do a substring but it didn't work.
Here is the query(s) i tried:
(1)
SELECT SUBSTR((F4105.COUNCS/10000 AS 'co'),length((co)-5) FROM F4105
(2)
SELECT SUBSTR((F4105.COUNCS/10000),length((F4105.COUNCS/10000)-5)) FROM F4105
The 1st query gave me and error:
Token F4105 was not valid. Valid tokens: (.
The 2nd query worked by wrong output.
SUBSTR
00
000000
000000
000000
000000
000000

Answer 1

You are mixing the column alias definition in the expression. So, the correct expression is more like:
SELECT SUBSTR(F4105.COUNCS/10000, length(F4105.COUNCS/10000.0) - 5) as coFROM F4105
I wouldn't recommend doing this, however. You have a numeric expression. Just convert it to a decimal representation that you want, say:
SELECT CAST(F4105.COUNCS/10000.0 as DECIMAL(10, 5))

Answer 2

The syntax for SUBSTR scalar is effectively SUBSTR(expression, start-pos, for-length) IBM i 7.1->Database->Reference->SQL reference->Built-in functions->Scalar functions->SUBSTR
The LENGTH() expression shown used in the OP is specified for the second argument; i.e. the start-pos argument. As a starting position, the result of that string-length minus five calculation is conspicuously incorrect for obtaining the leftmost data; i.e. the starting-position is five bytes less than the length of the string. That would locate, of course, some insignificant zeroes five bytes from the end of the string-representation of the decimal-result of the division.
As effective correction therefore, would be either of • insert the constant integer value of 1 for the start-pos argument [thus making the LENGTH() expression become the third argument] • replace the SUBSTR scalar with the LEFT scalar.Either of those revisions would achieve something that at least resembles what is alluded as the desired output. However without either of the DDL and what should be the explicit output being expressed in the OP, the actual effect of those revised expressions could only be guessed.Anyhow, even with either of those changes, those suggested alternative character-string expressions remain as similarly poor [approaching daft] choice of expressions as the one in the OP, per lack of explicit casting; i.e. the two revised expressions suggested as possibly corrective [yet that remain similarly unlikely to yield desirable results] are:
SUBSTR((F4105.COUNCS/10000), 1,length((F4105.COUNCS/10000)-5))
LEFT((F4105.COUNCS/10000),length((F4105.COUNCS/10000)-5))
Having established data-type\length attributes using explicit casting [i.e. established even without some actual DDL to do so] in a derived-table expression that generates the input values that would produce the output shown in the OP, from a list of literal numeric values, the character-string expression in the following query ensures that only the eleven digits of decimal-precision to the right of the decimal point [i.e. the scale] are maintained; thus visually, the effect is that the trailing five digits are truncated:
with F4105 (COUNCS) as ( values
( dec( 1111643. , 9, 2 ) )
,( dec( 1111633. , 9, 2 ) )
,( dec( 1111633. , 9, 2 ) )
,( dec( 1017654. , 9, 2 ) )
,( dec( 1017654. , 9, 2 ) )
,( dec( 1127258. , 9, 2 ) )
)
SELECT cast( dec( (F4105.COUNCS/10000), 17, 11 ) as varchar(19) )
FROM F4105