Can you compare text alphabetically in a WHERE clause? - sql

I'm using SQLite, and I need to do the following:
SELECT * FROM fruit WHERE name<='banana'
This statement should return all entries whose "name" column contains text that comes alphabetically before (or is equal to) the word "banana". So it should return the row with "apple", but not the row with "pear" or "orange".
It appears that simply using the <= operator doesn't work, so is there another way?

It should work. But beware: comparison is binary. 'A' < 'a' in ASCII. To compare alphabetically, without sensitivity to case, you should do wHERE LOWER(my_column) < 'value'

Related

Natural or Human Sort order

I have been working on this on for months. I just cannot get the natural (True alpha-numeric) results. I am shocked that I cannot get them as I have been able to in RPG since 1992 with EBCDIC.
I am looking for any solution in SQL, VBS or simple excel or access. Here is the data I have:
299-8,
3410L-87,
3410L-88,
420-A20,
420-A21,
420A-40,
4357-3,
AN3H10A,
K117GM-8,
K129-1,
K129-15,
K271B-200L,
K271B-38L,
K271D-200EL,
KD1051,
KD1062,
KD1092,
KD1108,
KD1108,
M8000-3,
MS24665-1,
SK271B-200L,
SAYA4008
The order I am looking for is the true alpha-numeric order as below:
AN3H10A,
KD1051,
KD1062,
KD1092,
KD1108,
KD1108,
K117GM-8,
K129-1,
K129-15,
MS24665-1,
M8000-3,
SAYA4008,
SK271B-200L
The inventory is 7800 records so I have had some problems with processing power as well.
Any help would be appreciated.
Jeff
In native Excel, you can add multiple sorting columns to return the ASCII code for each character, but if the character is a number, then add a large number to the code (e.g 1000).
Then sort on each of the helper columns, including the first column in the table, but not in the sort.
The formula:
=IFERROR(CODE(MID($A1,COLUMNS($A:A),1))+AND(CODE(MID($A1,COLUMNS($A:A),1))>=48,CODE(MID($A1,COLUMNS($A:A),1))<=57)*1000,"")
The Sort dialog:
The results:
You can implement a similar algorithm using VBA, and probably SQL also. I dunno about VBS or Access.
You could try using format for left padding the string in order by
select column
from my_table
order by Format(column, "0000000000")
Add a sorting column:
, iif (left(fieldname, 1) between '0' and '9', 1, 0) sortField
etc
order by sortField, FieldName
Lets say you have your data in column "A". If you put this formula in column "B" =IFERROR(IF(LEFT(A1,1)+1>0,"ZZZZZZZ "&A1,A1),A1), it will automatically add Z in front of all numerical values, so that they will naturally appear after all alphabetical values when you sort A-Z. later you can find&replace that funny ZZZZZZ string...
There a number of approaches, but likely the least amount of work is to build two columns that split out the delimiter (-) in this case.
You then “pad” the results (spaces, or 0) right justified, and then sort on the two columns.
So in the query builder we have this:
SELECT Field1,
Format(
Mid(field1,1,IIf(InStr(field1,"-")=0,50,InStr(field1,"-")-1)),
">##########") AS Expr1,
Format(
Mid(field1,IIf(InStr(field1,"-")=0,99,InStr(field1,"-")+1)),
">##########") AS Expr2
FROM Data
When we run the above raw query we get this:
So now in the query builder, simply sort on the first derived column, and then sort on the 2nd derived column.
Eg this:
Run the query, and we get this result:
Edit:
Looking at you desired results, it looks like above sort is wrong. We have to RIGHT just and pad with 0’s.
So this 2nd try:
SELECT Field1,
Left(Mid(field1,1,IIf(InStr(field1,"-")=0,30,InStr(field1,"-")-1))
& String(30,"0"),30) AS Expr1,
Left(Mid(field1,IIf(InStr(field1,"-")=0,99,InStr(field1,"-")+1))
& String(30,"0"),30) AS Expr2
FROM Data
The results are thus this:
Given your small table size, then the above query should perform quite well.

PostgreSQL - Assign integer value to string in case statement

I need to select one and only 1 row of data based on an ID in the data I have. I thought I had solved this (For details, see my original question and my solution, here: PostgreSQL - Select only 1 row for each ID)
However, I now still get multiple values in some cases. If there is only "N/A" and 1 other value, then no problem.. but if I have multiple values like: "N/A", "value1" and "value2" for example, then my case statement is not sufficient and I get both "value1" and "value2" returned to me. This is the case statement in question:
CASE
WHEN "PQ"."Value" = 'N/A' THEN 1
ELSE 0
END
I need to give a unique integer value to each string value and then the problem will be solved. The question is: how do I do this? My first thought is to somehow convert the character values to ASCII and sum them up.. but I am not sure how to do that and also worried about performance. Is there a way to very simply assign a value to each string so that I can choose 1 value only? I don't care which one actually... just that it's only 1.
EDIT
I am now trying to create a function to add up the ASCII values of each character so I can essentially change my case statement to something like this:
CASE
WHEN "PQ"."Value" = 'N/A' THEN 9999999
ELSE SumASCII("PQ"."Value")
END
Having a small problem with it though.. I have added it as a separate question, here: PostgreSQL - ERROR: query has no destination for result data
EDIT 2
Thanks to #Bohemian, I now have a working solution, which is as follows:
CASE
WHEN "PQ"."Value" = 'N/A' THEN -1
ELSE ('x'||LPAD(MD5("PQ"."Value"),16,'0'))::bit(64)::bigint
END DESC
This will produce a "unique" number for each value:
('x'||substr(md5("PQ"."Value"),1,8))::bit(64)::bigint
Strictly speaking, there is a chance of a collision, but it's very remote.
If the result is "too big", you could try modulus:
<above-calculation> % 10000
Although collisions would then be a 0.01% chance, you should try this formula against all known values to ensure there are no collisions.
If you don't care which value gets picked, change RANK() to ROW_NUMBER(). If you do care, do it anyway, but also add another term after the CASE statement in ORDER BY, separated by a comma, with the logic you want - for example if you want the first value alphabetically, do this:
...
ORDER BY CASE...END, "PQ"."Value")
...

how to use sql to Check if a certain column value contains another certain column value

I have a table, with 2 specific columns "log_number" and "message"
The "message" text value should contain the "log_number" value
Now I want to write a sql select to check if there is any bad rows which break the rules ! how can I do it ...
If I understand your question... this will list the records for which the log_number string is not contained in your message string:
SELECT *
FROM your_table
WHERE instr(message, log_number) < 1;

Problem with MySQL Select query with "IN" condition

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

How do I sort a VARCHAR column in PostgreSQL that contains words and numbers?

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