Simply speaking, I two rule tables, one lists all the rules, the other lists details of the rules:
Rule_ID Rule_Name
1 "Rule Name 1"
2 "Rule Name 2"
Target_Rule_ID Condition
1 >10
1 <20
1 !=15
1 !=18
2 >30
Meaning: for Rule_ID number 1, the value is more than 10, less then 20, and not eqaul to 15 nor 18.
I need to apply this rule to another data table, like:
ID Value
1 11
2 60
3 15
And make the result like:
ID Value Rule_ID
1 11 1
2 60 2
3 15 null
The current method I can think of is use a high level language like python.
get the rules all out
make the where clause
join the table one by one
But sounds inefficient, since that means I need to join the rule with the data table X times (X = total rule number).
I wonder is there a better way to do this directly in sql server? Any suggestions?
(Also assume the rules don't conflict with each other, that would make the problem even harder)...
Regardless of where you do it, you need a way to separate the numerical value from its rule expression (condition, like <10 etc). Have you thought about separating expressions and values?
Something like
rule_details table:
t_rule_id rule_type Value
1 > 10
1 < 20
joining that set to the set of information to be checked/validated. With a lot of case statements
case
when rule_type = '>' and value > other_value then true
when rule_type = '>' and value <= other_value then false
...
end as rule_satisfied
you can create a column to validate each number against the criteria set out in the rule details. At that point you can do a logical AND on each group created -> if TRUE then all rules satisfied.
Related
I'm creating a new table and carrying over several columns from a previous table. One of the new fields that I need to create is a flag that will have values 0 or 1 and value needs to be determined based on 6 previous fields in the table.
The 6 previous columns have preexisting values of 0 or 1 stored for each one. This new field needs to check whether any of the 6 columns have 1 and if so set the flag to 0. If there is 0 in all 6 fields then set itself to 1.
Hopefully this makes sense. How can I get this done in oracle? I assume a case statement and some sort of forloop?
You can use greatest() function: GREATEST
create table t_new
as
select
case when greatest(c1,c2,c3,c4,c5,c6)=1 -- at least one of them contains 1
then 0
else 1
end c_new
from t_old;
Or even shorter:
create table t_new
as
select
1-greatest(c1,c2,c3,c4,c5,c6) as c_new
from t_old;
In case of greatest = 1, (1-1)=0, otherwise (1-0)=1
You can use a virtual column with a case expression; something like:
flag number generated always as (
case when val_1 + val_2 + val_3 + val_4 + val_5 + val_6 = 0 then 1 else 0 end
) virtual
db<>fiddle
or the same thing with greatest() as #Sayan suggested.
Using a virtual column means the flag will be right for newly-inserted rows, and if any of the other values are updated; you won't have to recalculate or update the flag column manually.
I've assumed the other six columns can't be null and are constrained to only be 0 or 1, as the question suggests. If they can be null you can add nvl() or coalesce() to each term in the calculation.
Problem
I've got a dropdown list, which shows all the Article_Group_ID's that are linked to a specific brand, using the following Query:
SELECT TbArticle.Article_Group_ID, TbArticle.Article_Brand_ID
FROM TbArticle
GROUP BY TbArticle.Article_Group_ID, TbArticle.Article_Brand_ID,
HAVING (((TbArticle.Article_Brand_ID)=1))
This works as expected, it returns the following:
Query results
Article_Brand_ID
Article_Group_ID
1
1
1
2
But, if a user does not wish to specify a specific Article_Brand_ID, the query results look like this:
Query
Article_Brand_ID
Article_Group_ID
1
1
2
1
3
1
1
2
As you can see, the same Article_Group_ID is returned three times. Because of this, the user now sees the same group three times, instead of just once. If I were to remove the Article_Brand_ID from the query, the results would look like this:
Article_Group_ID
1
2
Is there any way to achieve the same behavior, by "ignoring" the Article_Brand_ID column, if it's WHERE clause is not set?
Database layout
TbArticle
Article_Brand_ID
Article_Group_ID
1
1
2
1
3
1
1
2
A single query cannot return a variable number of columns. So, strictly speaking you cannot do what you want with a single query. However, if you are willing to accept the second column as NULL when the brand is not provided, then you can adjust the aggregation.
Let me denote the parameter by ?:
SELECT a.Article_Group_ID,
IIF(? IS NOT NULL, a.Article_Brand_ID, NULL) as Article_Brand_ID
FROM TbArticle as a
WHERE a.Article_Brand_ID = ? OR
? IS NULL
GROUP BY a.Article_Group_ID,
IIF(? IS NOT NULL, a.Article_Brand_ID, NULL);
Note: It is usually better to filter before aggregating (i.e. using WHERE) rather than filtering afterwards (i.e. using HAVING).
I may be trying it wrong. I am looking for any approach which is best.
Requirement:
My Query joins 4-5 tables based on few fields.
I have a column called product id. In my table there are 1.5 million rows. Out of those only 10% rows has product ids with the following attribute
A300X-%
A500Y-%
300,500, 700 are valid model numbers. X and Y are classifications. My query picks all the systems.
I have a check as follows
CASE
WHEN PID LIKE 'A300X%'
THEN 'A300'
...
END AS MODEL
Similarly
CASE
WHEN PID LIKE 'A300X%'
THEN 'X'
...
END AS GENRE
I am looking for the best option from the below
How do I Combine both case statement and add another[third] case which will have these two cases. i.e
CASE
WHEN desc in ('AAA')
First Case
Second Case
ELSE
don't do anything for other systems
END
Is there any regex way of doing this? Before first - take the string. Look for X, Y and also 300,500,700.
Is there any other way of doing this? Or doing via code is the best way?
Any suggestions?
EDIT:
Sample desc:
AAA,
SoftwARE,
sw-app
My query picks all the desc. But the case should be running for AAA alone.
And Valid models are
A300X-2x-P
A500Y-5x-p
A700X-2x-p
A50CE-2x-P
I have to consider only 300,500,700. And the above two cases.
Expected result:
MODEL GENRE
A300 X
A500 Y
A300 Y
Q: How do I Combine both CASE statement expressions
Each CASE expression will return a single value. If the requirement is to return two separate columns in the resultset, that will require two separate expressions in the SELECT list.
For example:
DESC PID model_number genre
---- ---------- ------------ ------
AAA A300X-2x-P 300 X
AAA A500Y-5x-p 500 Y
AAA A700X-2x-p 700 X
AAA A50CE-2x-P (NULL) (NULL)
FOO A300X-2x-P (NULL) (NULL)
There will need to be an expression to return the model_number column, and a separate expression to return the genre column.
It's not possible for a single expression to return two separate columns.
Q: and add another[third] case which will have these two cases.
A CASE expression returns a value; we can use a CASE expression almost anywhere in a SQL statement where we can use a value, including within another CASE expression.
We can also combine multiple conditions in a WHEN test with AND and OR
As an example of combining conditions and nesting CASE expressions ditions...
CASE
WHEN ( ( t.PID LIKE '_300%' OR t.PID LIKE '_500%' OR t.PID LIKE '_700%' )
AND ( t.DESC = 'AAA' )
)
THEN CASE
WHEN ( t.PID LIKE '____X%' )
THEN 'X'
WHEN ( t.PID LIKE '____Y%' )
THEN 'Y'
ELSE NULL
END
ELSE NULL
END AS `genre`
There are other expressions that will return an equivalent result; the example shown here isn't necessarily the best expression. It just serves as a demonstration of combining conditions and nesting CASE expressions.
Note that to return another column model we would need to include another expression in the SELECT list. Similar conditions will need to be repeated; it's not possible to reference the WHEN conditions in another CASE expression.
Based on your sample data, logic such as this would work:
(CASE WHEN REGEXP_LIKE(PID, '^A[0-9]{3}[A-Z]-')
THEN SUBSTR(PID, 1, 4)
ELSE PID
END) AS MODEL
(CASE WHEN REGEXP_LIKE(PID, '^A[0-9]{3}[A-Z]-')
THEN SUBSTR(PID, 5, 1)
ELSE PID
END) AS GENRE
This assumes that the "model number" always starts with "A" and is followed by three digits (as in your example data). If the model number is more complicated, you may need regexp_substr() to extract the values you want.
I am using sql server management studio 2012 and have to make a query to show which subject a student has failed(condition for failing is point<5.0) the most for the first time from this table
StudentID | SubjectID | First/Second_Time | Point.
1 | 02 | 1 | 5.0
2 | 04 | 2 | 7.0
3 | 03 | 2 | 9
... etc
Here are my teacher's query:
SELECT SubjectID
FROM Result(NAME OF the TABLE)
WHERE [First/Second_Time] = 1 AND Point < 5
GROUP BY SubjectID
HAVING count(point) >= ALL
(
SELECT count(point)
FROM Result
WHERE [First/Second_Time] = 1 AND point < 5
GROUP BY SubjectID
)
I don't understand the reason for making the having query. Because Count(point) is always >=all(select count(point)
from Result
where First/Second_Time=1 and point<5
group by SubjectID), isnt it ?
and it doesn't show that the subject has most student fail for the first time. Thanks in advance and sorry for my bad english
The subquery is returning a list of the number of times a subject was failed (on the first attempt). It might be easier for you to see what it's doing if you run it like this:
SELECT SubjectID, count(point)
FROM Result
WHERE [First/Second_Time] = 1 AND point < 5
GROUP BY SubjectID
So if someone failed math twice and science once, the subquery would return:
2
1
You want to know which subject was failed the most (in this case, which subject was failed 2 or more times, since that is the highest number of failures in your subquery). So you count again (also grouping by subject), and use having to return only subjects with 2 or more failures (greater than or equal to the highest value in your subquery).
SELECT SubjectID
FROM Result
WHERE [First/Second_Time] = 1 AND Point < 5
GROUP BY SubjectID
HAVING count(point)...
See https://msdn.microsoft.com/en-us/library/ms178543.aspx for more examples.
Sounds like you are working on a project for a class, so I'm not even sure I should answer this, but here goes. The question is why the having clause. Have you read the descriptions for having and all ?
All "Compares a scalar value with a single-column set of values".
The scalar value in this case is count(point) or the number of occurrences of a subject id with point less than 5. The single-column set in this case is a list of the number of occurrences of every subject that has less than 5 points.
The net result of the comparison is in the ">=". "All" will only evaluate to true if it is true for every value in the subquery. The subquery returns a set of counts of all subjects meeting the <5 and 1st time requirement. If you have three subjects that meet the <5 and 1st time criteria, and they have a frequency of 1,2,3 times respectively, then the main query will have three "having" results; 1,2,3. Each of the main query results has to be >= each of the subquery results for that main value to evaluate true. So going through step by step, First main value 1 is >= 1, but isn't >= 2 so 1 drops because the "having" is false. Second main value 2 is >=1, is >= 2, but is not >= 3 so it drops. Third value, 3, evaluates true as >= 1, 2, and 3, so you end up returning the subject with the highest frequency.
This is fairly clear in the "remarks" section of the MSDN discussion of "All" keyword, but not as relates to your specific application.
Remember, MSDN is our friend!
I have a database table of my own that I am trying to construct a query for that seems simple enough, but I feel like I am messing up somewhere because the results are not what they should be.
I basically have a table that is like the following:
Table: Data
Columns:
Row ID Profile Import ID Field ID Product
1 5 Null 5 60 Can
2 0 Null 5 65 Hat
3 0 Null 5 70 Box
4 6 Null 6 60 Fish
I basically want to take the word "Hat" in row 2 and place it into the "Profile" column of row 1, replacing the null value there. I am doing this for multiple rows.
In the case of the multiple rows I want to take the "Profile" column and make it equal to the "Product" column. I only want this to happen in the rows where the "ID" value matches the "Import ID", and where the "Field ID" is 65 specifically. In the example above the "ID" 5 matches the "Import ID" 5, so I want to take the "Product" value "Hat" where the "Field ID" is 65, and place that value into the "Profile" column where the ID is 5. My table has over 9000 rows and 600 would have to be changed in this way, with various ID's needing various products inserted.
The result I would like would be:
Row ID Profile Import ID Field ID Product
1 5 Hat 5 60 Can
2 0 Null 5 65 Hat
3 0 Null 5 70 Box
4 6 Null 6 60 Fish
I pray that makes sense...
My query was this
UPDATE 'Data'
SET 'Profile'='Product'
WHERE 'ID'='Import ID' AND 'Field ID'=65;
I have also tried a subquery
UPDATE 'Data'
SET 'Profile'= (SELECT 'Product' FROM Data WHERE 'Field ID'=65)
WHERE 'ID'='Import ID';
This did not work and I am just wondering if there is some logic I missing. Thank you to anyone who can help, I have been up for a bit trying to understand this...
You need to join the data; something like:
UPDATE d1
SET d1.Profile = d2.Product
FROM [Data] d1 -- dest
INNER JOIN [DATA] d2 -- source
ON d2.[Import ID] = d1.[ID] AND d2.[Field ID] = 65
(note swapped 2 columns...)
A couple thing to keep in mind when learning sql:
it isnt a good idea to have spaces in column names. although they might be easier to read, it makes your queries more difficult. most databases dont allow them at all, and those that do have different ways to specify the columns in queries.
to work around your problem, perhaps you should try to enclose the column name in backticks (`), or in square brackets ([ ]).
in any case, instead of a space, please consider an underscore.
with that in mind you should also remember that not to put column names in quotes. something like
SELECT 'Product' FROM Data WHERE 'Field ID'=65
would not work for two reasons:
a. Selecting quoted text will return that quoted text. so were the where clause to return two rows, you would get the text 'Product' returned twice.
b. here your where clause is comparing the text 'Field ID' with the number 65, which would always be false.
hope that helps