I hava data in my database and i need to select all data where 1 column number is between 1-100.
Im having problems, because i cant use - between 1 and 100; Because that column is character varying, not integer. But all data are numbers (i cant change it to integer).
Code;
dst_db1.eachRow("Select length_to_fault from diags where length_to_fault between 1 AND 100")
Error - operator does not exist: character varying >= integer
Since your column supposed to contain numeric values but is defined as text (or version of text) there will be times when it does not i.e. You need 2 validations: that the column actually contains numeric data and that it falls into your value restriction. So add the following predicates to your query.
and length_to_fault ~ '^\+?\d+(\.\d*)?$'
and length_to_fault::numeric <# ('[1.0,100.0]')::numrange;
The first builds a regexp that insures the column is a valid floating point value. The second insures the numeric value fall within the specified numeric range. See fiddle.
I understand you cannot change the database, but this looks like a good place for a check constraint esp. if n/a is the only non-numeric are allowed. You may want to talk with your DBA ans see about the following constraint.
alter table diags
add constraint length_to_fault_check
check ( lower(length_to_fault) = 'n/a'
or ( length_to_fault ~ '^\+?\d+(\.\d*)?$'
and length_to_fault::numeric <# ('[1.0,100.0]')::numrange
)
);
Then your query need only check that:
lower(lenth_to_fault) != 'n/a'
The below PostgreSQL query will work
SELECT length_to_fault FROM diags WHERE regexp_replace(length_to_fault, '[\s+]', '', 'g')::numeric BETWEEN 1 AND 100;
Related
Is there any way to add a constraint on a column that is an array to limit length text objects?
I know that I can do this without constraint:
colA varchar(100)[] not null
I tried to do it in the following way:
alter table "tableA" ADD CONSTRAINT "colA_text_size"
CHECK ((SELECT max(length(pc)) from unnest(colA) as pc) <= 100) NOT VALID;
alter table "tableA" VALIDATE CONSTRAINT colA_text_size;
But got error: cannot use subquery in check constraint (SQLSTATE 0A000)
Try the following definition for your check constraint: (see demo, for demo I limit length to 25).
check (length(replace(array_to_string( text_array ,','), ',','')) <= 100)
What it does:
First the function array_to_string( ... ) converts the array to a csv.
The replace() function then removes the commas replacing them with the zero length string ''.
The length() function gets number of remaining characters in the string.
Finally that number is compared to the limit value (100) and the check constraint is either passed of failed.
References:
array_to_string(),
replace(), length()
Is there a way to check if a character varying type column contains only digits or null values with Postgresql?
Maybe something like (this syntax is incorrect):
SELECT *
FROM mytable
ORDER BY
CASE WHEN mycol ~ '^[0-9\.]+$' THEN 1 ELSE 0 END
LIMIT 1
I'm expecting TRUE or FALSE as final result for the whole column.
If you want to to know if the values in all rows are digits, you can use
select not exists (select *
from mytable
where not (mycol ~ '^[0-9\.]+$'))
Online example
To get Nulls use COALESCE(mycol, 1) -- will return 1 if the value in mycol is NULL.
For checking numerics you could use regex LIKE'^[0-9]*' it wont detect decimal dots (dont know if your data have decimals)
BR!
Wanted to create the multiple parameter of function but it gives me this error:
CREATE FUNCTION failed because a column name is not specified for
column 1.
Code below:
create function dmt.Impacted(
#nameOfColumn varchar , #nameOfParam varchar)
returns table
as
return
(select
case when '['+#nameOfColumn+']' is null or len(rtrim('['+#nameOfColumn+']')) = 0
then Convert(nvarchar(2),0)
else
#nameOfParam end from employee) ;
As the error message clearly said, the column in the returned result need a name. Either give it an alias in the SELECT like
SELECT CASE
...
END a_column_name
...
or define it in the declaration of the return type as in
...
RETURNS TABLE
(a_column_name nvarchar(max)
...
As you can see in the second form you have to specify a data type. As your current code doesn't make much sense now I cannot figure out what is the right one there. You'd need to amend it.
Note, that len(rtrim('['+#nameOfColumn+']')) = 0 is never true as len(rtrim('['+#nameOfColumn+']')) is either NULL, when #nameOfColumn is NULL or at least 2 because of the added brackets.
If #nameOfColumn is supposed to be a column name you shouldn't use varchar (especially without a length specified for it) but sysname which is a special type for object names.
Either way you should define a length for #nameOfColumn and #nameOfParam as just varchar without any length means varchar(1), which is probably not what you want. And maybe instead of varchar you want nvarchar.
You may also want to look into quotename().
Define name of column in SELECT statement :
(select case when '['+#nameOfColumn+']' is null or
len(rtrim('['+#nameOfColumn+']')) = 0
then Convert(nvarchar(2),0)
else #nameOfParam
end as name_column -- define column name
from employee)
Also, your function parameter has no data length, by default it will accept only 1 character #nameOfColumn varchar , #nameOfParam varchar & rest will trim.
I have field that has up to 9 comma separated values each of which have a string value and a numeric value separated by colon. After parsing them all some of the values between 0 and 1 are being set to an integer rather than a numeric as cast. The problem is obviously related to data type but I am unsure what is causing it or how to fix it. The problem only exists in the case statement, the split_part function seems to be working perfect.
Things I have tried:
nvl(split_part(one,':',2),0) = COALESCE types text and integer cannot be matched
nvl(split_part(one,':',2)::numeric,0) => Invalid input syntax for type numeric
numerous other cast/convert variations
(CASE WHEN split_part(one,':',2) = '' THEN 0::numeric ELSE split_part(one,':',2)::numeric END)::numeric => runs but get int value of 0
When using the split_part function outside of case statement it does work correctly. However, I need the result to be zero for null values.
split_part(one,':',2) => 0.02068278096187390979 (expected result)
When running the code above I get zero but expect 0.02068278096187390979
Field "one" has the following value 'xyz: 0.02068278096187390979' before the split_part function.
EXAMPLE:
create table test(one varchar);
insert into test values('XYZ: 0.50000000000000000000')
select
one ,split_part(one,':',2) as correct_value_for_those_that_are_not_null ,
case
when split_part(one,':',2) = '' then null
else split_part(one,':',2)::numeric
end::numeric as this_one_is_the_problem
from test
However, I need the result to be zero for null values.
Your example does not deal with NULL values at all, though. Only addressing the empty string ('').
To replace either with 0 reliably, efficiently and without casting issues:
SELECT part1, CASE WHEN part2 <> '' THEN part2::numeric ELSE numeric '0' END AS part2
FROM (
SELECT split_part(one, ':', 1) AS part1
, split_part(one, ':', 2) AS part2
FROM test
) sub;
See:
Best way to check for "empty or null value"
Also note that all SQL CASE branches must agree on a common data type. There have been minor adjustments in the logic that determines the resulting type in the past, so the version of Postgres may play a role in corner cases. Don't recall the details now.
nvl()is not a Postgres function. You probably meant COALESCE. The manual:
This SQL-standard function provides capabilities similar to NVL and IFNULL, which are used in some other database systems.
I am attempting to run a simple UPDATE script on an integer field, whereby the trailing 2 numbers are "kept", and the leading numbers are removed. For example, "0440" would be updated as "40." I can get the desired data in a SELECT statement, such as
SELECT RIGHT(field_name::varchar, 2)
FROM table_name;
However, I run into an error when I try to use this same functionality in an UPDATE script, such as:
UPDATE schema_name.table_name
SET field_name = RIGHT(field_name::varchar, 2);
The error I receive reads:
column . . . is of type integer but expression is of type text . . .
HINT: You will need to rewrite or cast the expression
You're casting the integer to varchar but you're not casting the result back to integer.
UPDATE schema_name.table_name
SET field_name = RIGHT(field_name::TEXT, 2)::INTEGER;
The error is quite straight forward - right returns textual data, which you cannot assign to an integer column. You could, however, explicitly cast it back:
UPDATE schema_name.table_name
SET field_name = RIGHT(field_name::varchar, 2)::int;
1 is a digit (or a number - or a string), '123' is a number (or a string).
Your example 0440 does not make sense for an integer value, since leading (insignificant) 0 are not stored.
Strictly speaking data type integer is no good to store the "trailing 2 numbers" - meaning digits - since 00 and 0 both result in the same integer value 0. But I don't think that's what you meant.
For operating on the numeric value, don't use string functions (which requires casting back and forth. The modulo operator % does what you need, exactly: field_name%100. So:
UPDATE schema_name.table_name
SET field_name = field_name%100
WHERE field_name > 99; -- to avoid empty updates