I have a column that will always be 5 digits long, and each digit will always be a 1 or a 0. I need to put in my where clause to exclude when the second position is equal to 1. For example 01000 is to be excluded but 10010 is to be kept. I currently have:
WHERE (SUBSTRING(field, 2, 1) <> '1') or field IS NULL
How do do this without using the Substring function?
Edit:Also, the column is a varchar(10) in the database. Does this matter?
You could use the like operator to check that character directly:
WHERE field LIKE '_1%' OR field IS NULL
Use LEFT and RIGHT and then check that is 1 or not as below-
WHERE RIGHT(LEFT(field,2),1) <> '1' OR field IS NULL
No.
If 'field' is of a string type, you need to use string functions to manipulate it. SUBSTRING or some other flavor of it.
You can also convert it to binary and use bitwise AND operator but that won't solve the root issue here.
You are facing the consequences of someone ignoring 1NF.
There is a reason why Codd insisted that every "cell" must be atomic. Your's is not.
Can you separate this bitmap into atomic attribute columns?
Related
I have a column in my table with these values:
PING_TO_ME_20100828_Any87
TO_THESE_D_COLUMN_ENTRY_20200825
TO_THESE_D_20100829_COLUMN_ENTRY
201901_ARE_YOU_TRYING_TO_REACH47
ASK_TO_UOU_201008
I need to separate date values in a separate column.
My output should be:
20100828
20200825
20100829
201901
201008
Any help is very much appreciated.
You will (and already have) likely get comments about this telling you to fix your design. And while that is likely true...I won't try to pick apart why you are doing this, and I'll just give you the answer you came here for.
Your goal is to pick out either an 8 digit string of integers, or a 6 digit string of integers.
Here is one way you could do it:
SELECT x.y
, COALESCE(SUBSTRING(x.y, NULLIF(PATINDEX('%[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]%', x.y), 0), 8)
, SUBSTRING(x.y, NULLIF(PATINDEX('%[0-9][0-9][0-9][0-9][0-9][0-9]%', x.y), 0), 6))
FROM (
VALUES ('PING_TO_ME_20100828_Any87'),
('TO_THESE_D_COLUMN_ENTRY_20200825'),
('TO_THESE_D_20100829_COLUMN_ENTRY'),
('201901_ARE_YOU_TRYING_TO_REACH47'),
('ASK_TO_UOU_201008')
) x(y)
Explanation:
Since you are looking for both 8 and 6 digit values, you need to check for the longer of the two first. So first I search for the occurrence of a string of 8 integers using:
NULLIF(PATINDEX('%[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]%', x.y), 0)
This returns the first position of a string of 8 integers. The reason I wrap it in a NULLIF() is because if the value is not found, then PATINDEX will return 0.
I use NULLIF() to return NULL in that case, essentially indicating nothing was found. If you pass a NULL value to SUBSTRING() then it also returns NULL.
This is all just a nice way of "failing over" to the 6 character string check.
So there I do the same thing again:
NULLIF(PATINDEX('%[0-9][0-9][0-9][0-9][0-9][0-9]%', x.y), 0)
Except this time, I only repeat [0-9] six times. And again, I use the NULLIF() trick, so that it returns NULL if no string is found.
Throw that all into SUBSTRING() and COALESCE() and you've got a function that returns the results you're looking for.
Potential downsides
There are a couple down sides to this method.
It is not checking for a valid date, it's simply looking for a string of either 8 integers, or 6 integers. It could be 12345678 and it would still detect and return that.
If there are strings of integers longer than 8 digits, it will grab only the first 8 characters.
If there are multiple occurrences of 6 or 8 character integer strings...it will only return the first one.
There are much more robust ways you could write this, but it all depends on your data and what you need to do.
Other methods
Another way it could be done depending on which version of SQL Server you are using, is using STRING_SPLIT().
SELECT x.y, s.[value]
FROM (
VALUES ('PING_TO_ME_20100828_Any87'),('TO_THESE_D_COLUMN_ENTRY_20200825'),('TO_THESE_D_20100829_COLUMN_ENTRY'),('201901_ARE_YOU_TRYING_TO_REACH47'),('ASK_TO_UOU_201008')
) x(y)
CROSS APPLY (
SELECT [value]
FROM STRING_SPLIT(x.y, '_')
WHERE [value] LIKE '[0-9][0-9][0-9][0-9][0-9][0-9][0-9][0-9]'
OR [value] LIKE '[0-9][0-9][0-9][0-9][0-9][0-9]'
) s
This method handles a couple of the downsides mentioned earlier. For example, it will ONLY return integer strings of length 6 or 8. It will also return ALL integer strings of length 6 or 8 and not just the first one.
And there's other ways to identify the strings as well, like using ISNUMERIC(x.[value]) or TRY_CONVERT(int, s.[value]).
It all depends on how you are using this code...if it's runs fast enough, and it's a one off script, then it really doesn't matter. If it's running for millions of records at a time, then yeah you should play around with other methods.
We have legacy table where one of the columns part of composite key was manually filled with values:
code
------
'001'
'002'
'099'
etc.
Now, we have feature request in which we must know MAX(code) in order to give user next possible value, in example case form above next value is '100'.
We tried to experiment with this but we still can't find any reasonable explanation how DB2 engine calculates that
MAX('001', '099', '576') is '576'
MAX('099', '99', 'www') is '99' and so on.
Any help or suggestion would be much appreciated!
You already have the answer to getting the maximum numeric value, but to answer the other part with regard to 'www','099','99'.
The AS/400 uses EBCDIC to store values, this is different to ASCII in several ways, the most important for your purposes is that Alpha characters come before numbers, which is the opposite of Ascii.
So on your Max() your 3 strings will be sorted and the highest EBCDIC value used so
'www'
'099'
'99 '
As you can see your '99' string is really '99 ' so it is higher that the one with the leading zero.
Cast it to int before applying max()
For the numeric maximum -- filter out the non-numeric values and cast to a numeric for aggregation:
SELECT MAX(INT(FLD1))
WHERE FLD1 <> ' '
AND TRANSLATE(FLD1, '0123456789', '0123456789') = FLD1
SQL Reference: TRANSLATE
And the reasonable explanation:
SQL Reference: MAX
This max working well in your type definition, when you want do max on integer values then convert values to integer before calling MAX, but i see you mixing max with string 'www' how you imagine this works?
Filter integer only values, cast it to int and call max. This is not good designed solution but looking at your problem i think is enough.
Sharing the solution for postgresql
which worked for me.
Suppose here temporary_id is of type character in database. Then above query will directly convert char type to int type when it gives response.
SELECT MAX(CAST (temporary_id AS Integer)) FROM temporary
WHERE temporary_id IS NOT NULL
As per my requirement I've applied MAX() aggregate function. One can remove that also and it will work the same way.
I found a weird problem with MySQL select statement having "IN" in where clause:
I am trying this query:
SELECT ads.*
FROM advertisement_urls ads
WHERE ad_pool_id = 5
AND status = 1
AND ads.id = 23
AND 3 NOT IN (hide_from_publishers)
ORDER BY rank desc
In above SQL hide_from_publishers is a column of advertisement_urls table, with values as comma separated integers, e.g. 4,2 or 2,7,3 etc.
As a result, if hide_from_publishers contains same above two values, it should return only record for "4,2" but it returns both records
Now, if I change the value of hide_for_columns for second set to 3,2,7 and run the query again, it will return single record which is correct output.
Instead of hide_from_publishers if I use direct values there, i.e. (2,7,3) it does recognize and returns single record.
Any thoughts about this strange problem or am I doing something wrong?
There is a difference between the tuple (1, 2, 3) and the string "1, 2, 3". The former is three values, the latter is a single string value that just happens to look like three values to human eyes. As far as the DBMS is concerned, it's still a single value.
If you want more than one value associated with a record, you shouldn't be storing it as a comma-separated value within a single field, you should store it in another table and join it. That way the data remains structured and you can use it as part of a query.
You need to treat the comma-delimited hide_from_publishers column as a string. You can use the LOCATE function to determine if your value exists in the string.
Note that I've added leading and trailing commas to both strings so that a search for "3" doesn't accidentally match "13".
select ads.*
from advertisement_urls ads
where ad_pool_id = 5
and status = 1
and ads.id = 23
and locate(',3,', ','+hide_from_publishers+',') = 0
order by rank desc
You need to split the string of values into separate values. See this SO question...
Can Mysql Split a column?
As well as the supplied example...
http://blog.fedecarg.com/2009/02/22/mysql-split-string-function/
Here is another SO question:
MySQL query finding values in a comma separated string
And the suggested solution:
http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_find-in-set
I need to order a select query using a varchar column, using numerical and text order. The query will be done in a java program, using jdbc over postgresql.
If I use ORDER BY in the select clause I obtain:
1
11
2
abc
However, I need to obtain:
1
2
11
abc
The problem is that the column can also contain text.
This question is similar (but targeted for SQL Server):
How do I sort a VARCHAR column in SQL server that contains words and numbers?
However, the solution proposed did not work with PostgreSQL.
Thanks in advance, regards,
I had the same problem and the following code solves it:
SELECT ...
FROM table
order by
CASE WHEN column < 'A'
THEN lpad(column, size, '0')
ELSE column
END;
The size var is the length of the varchar column, e.g 255 for varying(255).
You can use regular expression to do this kind of thing:
select THECOL from ...
order by
case
when substring(THECOL from '^\d+$') is null then 9999
else cast(THECOL as integer)
end,
THECOL
First you use regular expression to detect whether the content of the column is a number or not. In this case I use '^\d+$' but you can modify it to suit the situation.
If the regexp doesn't match, return a big number so this row will fall to the bottom of the order.
If the regexp matches, convert the string to number and then sort on that.
After this, sort regularly with the column.
I'm not aware of any database having a "natural sort", like some know to exist in PHP. All I've found is various functions:
Natural order sort in Postgres
Comment in the PostgreSQL ORDER BY documentation
I have the following SQL query:
select AuditStatusId
from dbo.ABC_AuditStatus
where coalesce(AuditFrequency, 0) <> 0
I'm struggling a bit to understand it. It looks pretty simple, and I know what the coalesce operator does (more or less), but dont' seem to get the MEANING.
Without knowing anymore information except the query above, what do you think it means?
select AuditStatusId
from dbo.ABC_AuditStatus
where AuditFrequency <> 0 and AuditFrequency is not null
Note that the use of Coalesce means that it will not be possible to use an index properly to satisfy this query.
COALESCE is the ANSI standard function to deal with NULL values, by returning the first non-NULL value based on the comma delimited list. This:
WHERE COALESCE(AuditFrequency, 0) != 0
..means that if the AuditFrequency column is NULL, convert the value to be zero instead. Otherwise, the AuditFrequency value is returned.
Since the comparison is to not return rows where the AuditFrequency column value is zero, rows where AuditFrequency is NULL will also be ignored by the query.
It looks like it's designed to detect a null AuditFrequency as zero and thus hide those rows.
From what I can see, it checks for fields that aren't 0 or null.
I think it is more accurately described by this:
select AuditStatusId
from dbo.ABC_AuditStatus
where (AuditFrequency IS NOT NULL AND AuditFrequency != 0) OR 0 != 0
I'll admit the last part will never do anything and maybe i'm just being pedantic but to me this more accurately describes your query.
The idea is that it is desireable to express a single search condition using a single expression but it's merely style, a question of taste:
One expression:
WHERE age = COALESCE(#parameter_value, age);
Two expressions:
WHERE (
age = #parameter_value
OR
#parameter_value IS NULL
);
Here's another example:
One expression:
WHERE age BETWEEN 18 AND 65;
Two expressions
WHERE (
age >= 18
AND
age <= 65
);
Personally, I have a strong personal perference for single expressions and find them easier to read... if I am familiar with the pattern used ;) Whether they perform differently is another matter...