I'm currently still learning SQL, however, I can't seem to actually find out how to exclude multiple usernames.
Example I have 2 columns at hand, 1 being username and another having the state of active or not.
UserName Status
===============
ABC Y
CDE Y
FGH Y
IJK Y
LMN Y
OPQ Y
QRS Y
and the list goes on. Example if I wanted to change the entire status from Y to N, the query would be similar to this.
update database
set status = 'N'
However if I want to add numerous values, I'm not sure how to query it out.
update database
set status = 'N'
where (username != 'ABC' or username != 'DEF')
would be great if someone could teach and explain step by step cause I can't seem to understand how people use specific functions such as t1 and t2 to solve this and group by as well.
Like NoDisplayName mentions in the latter part of his comment,
Use of NOT IN is your WHERE clause is the one required to exclude mutliple values. Like this :
update database
set status = 'N'
where username NOT IN ('ABC', 'CDE', 'XYZ')
If the values are to be drawn from a table/recordset based on some criterion you can use a select query after NOT IN instead of a list of values.
Related
I am new to SQL and working on a database that needs a binary indicator based on the presence of string values in a column. I'm trying to make a new table as follows:
Original:
Indicator
a, b, c
c, d, e
Desired:
Indicator
type
a, b, c
1
c, d, e
0
SQL code:
SELECT
ID,
Contract,
Indicator,
CASE
WHEN Indicator IN ('a', 'b')
THEN 1
ELSE 0
END as Type
INTO new_table
FROM old_table
The table I keep creating reports every type as 0.
I also have 200+ distinct indicators, so it will be really time-consuming to write each as:
CASE
WHEN Indicator = 'a' THEN '1'
WHEN Indicator = 'b' THEN '1'
Is there a more streamlined way to think about this?
Thanks!
I think the first step is to understand why your code doesn’t work right now.
If your examples of what’s Indicator column are literally the strings you noted (a, b, c in one string and c, d, e in another) you should understand that your case statement is saying “I am looking for an exact match on the full value of Indicator against the following list -
The letter A or
The letter B
Essentially- you are saying “hey SQL, does ‘a,b,c’ match to ‘a’? Or does ‘a,b,c’ match to ‘b’. ?”
Obviously SQL’s answer is “these don’t match” which is why you get all 0s.
You can try wildcard matching with the LIKE syntax.
Case when Indicator like ‘%a%’ or Indicator like ‘%b%’ then 1 else 0 end as Type
Now, if the abc and cde strings aren’t REALLY what’s in your database then this approach may not work well for you.
Example, let’s say your real values are words that are all slapped together in a single string.
Let’s say that your strings are 3 words each.
Cat, Dog, Man
Catalog, Stick, Shoe
Hair, Hellcat, Belt
And let’s say that Cat is a value that should cause Type to be 1.
If you write: case when Indicator like ‘%cat%’ then 1 else 0 end as Type - all 3 rows will get a 1 because the wildcard will match Cat in Catalog and cat in Hellcat.
I think the bottom line is that unless your Indicator values really are 3 letters and your match criteria is a single letter, you very well could be better off writing a 200 line long case statement if you need this done any time soon.
A better approach to consider (depending on things like are you going to have 300 different combinations a week or month or year from now?)
If yes, wouldn’t it be nice if you had a table with a total of 6 rows - like so?
Indicator | Indictor_Parsed
a,b,c | a
a,b,c | b
a,b,c | c
c,d,e | c
c,d,e | d
c,d,e | e
Then you could write the query as you have it case when Indicator_Parsed in (‘a’, ‘b’) then 1 else 0 end as Type - as a piece of a more verbose solution.
If this approach seems useful to you, here’s a link to the page that lets you parse those comma-separated-values into additional rows. Turning a Comma Separated string into individual rows
ON mysql/sql server You can do it as follows :
insert into table2
select Indicator,
CASE WHEN Indicator like '%a%' or Indicator like '%b%' THEN 1 ELSE 0 END As type
from table1;
demo here
You can use the REGEXP operator to check for presence of either a, b or both.
SELECT Indicator,
Indicator REGEXP '.*[ab].*'
FROM tab
If you need that into a table, you either create it from scratch
CREATE your_table AS
SELECT Indicator,
Indicator REGEXP '.*[ab].*'
FROM tab
or you insert values in it:
INSERT INTO your_table
SELECT Indicator,
Indicator REGEXP '.*[ab].*'
FROM tab
Check the demo here.
An update query like:
UPDATE test
SET x = (case when id = 1 then 99
when id = 2 then 98
end),
y = (case when id = 1 then 42
when id = 2 then 41
end)
will update multiple records where the x and y attributes have different values for each record. But what if the number of records I need to update is dynamic? For simplicity, assume I have an array of id values. I want to update all the records that have an id in that array, and in one query. How could you do that?
It seems like you're already going about this the hard way. Your code is best accomplished with multiple queries:
UPDATE test
SET x = 99, y=42
WHERE id=1;
UPDATE test
SET x = 98, y=41
WHERE id=2;
As for updating "all the records" (as you say), that's a harder question to answer, as it's not clear where the data are coming from. That sort of thing might be best handled with a scripting language. You may have other options. depending on which database platform you're using, but you didn't specify that either.
I had a built a query previously that returned zero duplicates until I decided to join in a couple more tables. Now that I've joined them in, I'm unable to create the desired flag due to duplicates being returned. I've attached the scenario below as an example.
I only want one occurrence of each reference number (123456789). I want to create a flag when certain criteria are met. For example, I want to see when reference numbers for a certain account meet "X", but when I join the table I get every instance of that reference number in the joined table.
REFNO BEG END STATUS
123456789 123 456 E
123456789 456 789 E
123456789 789 012 A
I want to see all of the REFNO's based on other parameters set in the query, but I want a flag for anything where END = '012'. I can't left join to the table because I will get all three lines. If I do an inner join then I just get the 012 lines. I Tried the code below in my select statement to only pull when that scenario exists, but I'm getting wacky returns and don't know why. I feel like this should be fairly easy to accomplish, but I can't wrap my head around how to create a flag for just that scenario without getting duplicates or removing results with an inner join.
,(CASE WHEN EXISTS(SELECT 1
FROM QW.ABCD Z
WHERE Z.ABCD = P.ABCD
AND Z.END = '012'
AND Z.TIMESTAMP IS NULL
AND Z.STATUS IN ('A','E'))
THEN 'Y' ELSE 'N'
END)
AS "FLAG"
Please help as I'm not sure what I'm doing wrong to get the flag I want to see.
I am not sure id DB2 allows this combination of UNION and GROUP BY, but what you want is probably something like this:
SELECT 'N' AS FLAG, REF_NO,MIN(BEG),MAX(THEEND) FROM TAB_QW A
WHERE NOT EXIST (SELECT * FROM TAB_QW B WHERE B.REF_NO = A.REF_NO AND B.THEEND = '012')
GROUP BY REF_NO
UNION
SELECT 'Y' AS FLAG, REF_NO,MIN(BEG),MAX(THEEND) FROM TAB_QW C
WHERE EXISTS (SELECT * FROM TAB_QW D WHERE D.REF_NO = C.REF_NO AND D.THEEND = '012')
GROUP BY REF_NO
I have a table with few columns and I want to achieve the following functionality using DB2 query.
say for e.g. USR table has User ID column and Option ID column
USER ID OPTION ID
1 1
1 5
1 22
1 100
1 999
I want to write a query and result should be next available number in sequence.
So when the first time query will be executed, it should return me the next
available option ID as 2, so user will enter #2, so DB would have now
USER ID OPTION ID
1 1
1 2
1 5
1 22
1 100
1 999
so now when the query will be executed, it will show me available Option ID as 3.
Can somebody help to get the optimized query to get the correct results?
Please note that I think that exposing option_id to the user is a terrible idea, business requirement or no. Surrogate id's like this are meant to be completely hidden from the end user ('natural' keys, like credit-card numbers, obviously have to be exposed, but still shouldn't be dictated in this manner).
The following should work on any version of DB2:
SELECT a.optionid + :nextIncrement as next_value
FROM Usr as a
LEFT JOIN Usr as b
ON b.userid = a.userid
AND b.optionid = a.optionid + :nextIncrement
WHERE a.userid = :userId
AND b.userid IS NULL
ORDER BY a.optionid ASC
FETCH FIRST 1 ROW ONLY
(statement run against a local table on my iSeries instance, with host variables replaced)
Again, I strongly recommend you not use this, and see about getting the business requirement changed.
I am working in Teradata with some descriptive data that needs to be transformed from a gerneric varchar(60) into the different field lengths based on the type of data element and the attribute value. So I need to take whatever is in the Varchar(60) and based on field 'ABCD' act on field 'XYZ'. In this case XYZ is a varchar(3). To do this I am using CASE logic within my select. What I want to do is
eliminate all occurances of non alphabet/numeric data. All I want left are upper case Alpha chars and numbers.
In this case "Where abcd = 'GROUP' then xyz should come out as a '000', '002', 'A', 'C'
eliminate extra padding
Shift everything Right
abcd xyz
1 GROUP NULL
2 GROUP $
3 GROUP 000000000000000000000000000000000000000000000000000000000000
4 GROUP 000000000000000000000000000000000000000000000000000000000002
5 GROUP A
6 GROUP C
7 GROUP r
To do this I have tried TRIM and SUBSTR amongst several other things that did not work. I have pasted what I have working now, but I am not reliably working through the data within the select. I am really looking for some options on how to better work with strings in Teradata. I have been working out of the "SQL Functions, Operators, Expressions and Predicates" online PDF. Is there a better reference. We are on TD 13
SELECT abcd
, CASE
-- xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
WHEN abcd= 'GROUP'
THEN(
CASE
WHEN SUBSTR(tx.abcd,60, 4) = 0
THEN (
SUBSTR(tx.abcd,60, 3)
)
ELSE
TRIM (TRAILING FROM tx.abcd)
END
)
END AS abcd
FROM db.descr tx
WHERE tx.abcd IS IN ( 'GROUP')
The end result should look like this
abcd xyz
1 GROUP 000
2 GROUP 002
3 GROUP A
4 GROUP C
I will have to deal with approx 60 different "abcd" types, but they should all conform to the type of data I am currently seeing.. ie.. mixed case, non numeric, non alphabet, padded, etc..
I know there is a better way, but I have come in several circles trying to figure this out over the weekend and need a little push in the right direction.
Thanks in advance,
Pat
The SQL below uses the CHARACTER_LENGTH function to first determine if there is a need to perform what amounts to a RIGHT(tx.xyz, 3) using the native functions in Teradata 13.x. I think this may accomplish what you are looking to do. I hope I have not misinterpreted your explanation:
SELECT CASE WHEN tx.abcd = 'GROUP'
AND CHARACTER_LENGTH(TRIM(BOTH FROM tx.xyz) > 3
THEN SUBSTRING(tx.xyz FROM (CHARACTER_LENGTH(TRIM(BOTH FROM tx.xyz)) - 3))
ELSE tx.abcd
END
FROM db.descr tx;
EDIT: Fixed parenthesis in SUBSTRING