I am working with a table that contains two versions of stored information. To simplify it, one column contains the old description of a file run while another column contains the updated standard for displaying ran files. It gets more complicated in that the older column can have multiple standards within itself. The table:
Old Column New Column
Desc: LGX/101/rpt null
null Home
Print: LGX/234/rpt null
null Print
null Page
I need to combine the two columns into one, but I also need to delete the "Print: " and "Desc: " string from the beginning of the old column values. Any suggestions? Let me know if/when I'm forgetting something you need to know!
(I am writing in Cache SQL, but I'd just like a general approach to my problem, I can figure out the specifics past that.)
EDIT: the condition is that if substr(oldcol,1,5) = 'desc: ' then substr(oldcol,6)
else if substr(oldcol,1,6) = 'print: ' then substr(oldcol,7) etc. So as to take out the "desc: " and the "print: " to sanitize the data somewhat.
EDIT2: I want to make the table look like this:
Col
LGX/101/rpt
Home
LGX/234/rpt
Print
Page
It's difficult to understand what you are looking for exactly. Does the above represent before/after, or both columns that need combining/merging.
My guess is that COALESCE might be able to help you. It takes a bunch of parameters and returns the first non NULL.
It looks like you're wanting to grab values from new if old is NULL and old if new is null. To do that you can use a case statement in your SQL. I know CASE statements are supported by MySQL, I'm not sure if they'll help you here.
SELECT (CASE WHEN old_col IS NULL THEN new_col ELSE old_col END) as val FROM table_name
This will grab new_col if old_col is NULL, otherwise it will grab old_col.
You can remove the Print: and Desc: by using a combination of CharIndex and Substring functions. Here it goes
SELECT CASE WHEN CHARINDEX(':',COALESCE(OldCol,NewCol)) > 0 THEN
SUBSTRING(COALESCE(OldCol,NewCol),CHARINDEX(':',COALESCE(OldCol,NewCol))+1,8000)
ELSE
COALESCE(OldCol,NewCol)
END AS Newcolvalue
FROM [SchemaName].[TableName]
The Charindex gives the position of the character/string you are searching for.
So you get the position of ":" in the computed column(Coalesce part) and pass that value to the substring function. Then add +1 to the position which indicates the substring function to get the part after the ":". Now you have a string without "Desc:" and "Print:".
Hope this helps.
Related
I have been using sql for quite a time but unable to figure out below query logic.
I'm extracting two values
First_name i.e abc
FIRST_NAMES_LIST (list containing first names) i.e ['abc','abc','cba','dba'] (this may contain junk values also in between strings)
I trying to search first_name in first_name_list and return 1 or 0, using below logic
CASE FIRST_NAME in FIRST_NAMES_LIST then 1
else 0
but this isn't giving correct result
Can somebody please help.
Thanks,
Naseer
Look this information:
https://www.techonthenet.com/oracle/functions/instr.php
INSTR is a function which return <> 0 if your parameter match. If not it return 0.
I no have any clear example in your ennunciate to give you the correct answer. See the functionalities.
Regards!
Ideally you would parse out your json into a table object ( I don't know how to do that in Oracle) and then search your table object where the object contains the value, but that is pretty expensive. It would be more robust and would be able to handle special characters/corner cases better.
On the other hand, if the names are going to stay simple (ie, no quote marks ' or commas), you could use a LIKE expression and search the string.
CASE WHEN FIRST_NAMES_LIST LIKE '%''' + FIRST_NAME + '''%' THEN 1 ELSE 0 END
Yes im currently using INSTR but query is taking bit of time. hope resolves this issue. thanks.
I want to add a column called "Sweep" that contains bools based on whether the "Result" was a sweep or not. So I want the value in the "Sweep" column to be True if the "Result" is '4-0' or '0-4' and False if it isn't.
This is a part of the table:
I tried this:
ALTER TABLE "NBA_finals_1950-2018"
ADD "Sweep" BOOL;
UPDATE "NBA_finals_1950-2018"
SET "Sweep" = ("Result" = '4-0' OR "Result" = '0-4');
But for some reason, when I run this code...:
SELECT *
FROM "NBA_finals_1950-2018"
ORDER BY "Year";
...only one of the rows (last row) has the value True even though there are other rows where the result is a sweep ('4-0' or '0-4') as shown in the picture below.
I don't know why this is happening but I guess there is something wrong with the UPDATE...SET code. Please help.
Thanks in advance.
NOTE: I am using PostgreSQL 13
This would occur if the strings are not really what they look like -- this is often due to spaces at the beginning or end. Or perhaps to hyphens being different, or other look-alike characters.
You just need to find the right pattern. So so with a select. This returns no values:
select *
from "NBA_finals_1950-2018"
where "Result" in ('4-0', '0-4');
You can try:
where "Result" like '%0-4%' or
"Result" like '%4-0%'
But, this should do what you want:
where "Result" like '%4%' and
"Result" like '%0%'
because the numbers are all single digits.
You can incorporate this into the update statement.
Note: double quotes are a bad idea. I would recommend creating tables and columns without escaping the names.
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")
...
I am trying to connect a Filemaker DB to Firebird SQL DB in both ways import to FM and export back to Firebird DB.
So far it works using the MBS Plug-in but FM 13 Pro canot handle NULL.
That means that for example Timestamp fields that are empty (NULL) produce a "0" value.
Thats means in Time something like 01.01.1889 00:00:00.
So my idea was to simply ignore fields containing NULL.
But here my poor knowlege stops.
First I thought I can do this with WHERE, but this is ignoring whole records sets:
SELECT * FROM TABLE WHERE FIELD IS NOT NULL
Also I tried to filter it later on like this:
If (IsEmpty (MBS("SQL.GetFieldAsDateTime"; $command; "FIELD") ) = 0 ; MBS("SQL.GetFieldAsDateTime"; $command; "FIELD"))
With no result either.
This is a direct answer to halfbit's suggestion, which is correct but not for this SQL dialect. In a query to provide a replacement value when a field is NULL you need to use COALESCE(x,y). Where if X is null, Y will be used, and if Y is null then the field is NULL. Thats why it is common for me to use it like COALESCE(table.field,'') such that a constant is always outputted if table.field happens to be NULL.
select COALESCE(null,'Hello') as stackoverflow from rdb$database
You can use COALESCE() for more than two arguments, I just used two for conciseness.
I dont know the special SQL dialect, but
SELECT field1, field2, value(field, 0), ...FROM TABLE
should help you:
value gives the first argument, ie, your field if it is NOT NULL or the second argument if it is.
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