In my database table there are two fields named salary_to and salary_from.Now in front end of my website user can enter a salary in an input field say 20000.Now i wanna perform a check in the database that if any row have salaryto and salaryfrom between which the value '20000' lies.
My desired algo looks like something like this
SELECT all ROW where salaryto is less than 20000 and salaryfrom is greater than 20000
Can i use the between operator to perform this kind of filterring or i just ave to use >,< operator to this?
Provided that I'm using mysql database for my project.
The between operator is INCLUSIVE meaning it includes the START and END Value. While < > are exclusive.
SELECT *
FROM tableName
WHERE salaryto < 20000 and salaryfrom > 20000
So the rows that are fetched here are with salaryto value of 19999 and below AND salaryfrom value of 20001 and above, assuming that it increases by 1.
You can use this:
SELECT * FROM yourTable WHERE 2000 BETWEEN salary_to AND salary_from
But this is Recommended:
SELECT * FROM yourTable WHERE (salary_to < 2000) and (salary_from > 2000)
Related
I have a data set like that:
Data Set Contents
From To Comment
----+---+--------
0 50 Bad
50 70 Good
70 100 Excellent
If I have a value of 75, I need to get Excellent by searching the Dataset.
I know about the lookup function but it is not what I want. How can I do that?
The values should be in percentage.
Note : the value (75) is Average of a column (Calculated) it
calculate student grade from max and student mark Version SQL Server
2016
Note 2 : the dataset is from database not static values
Thank You
Assuming you only ever have a fixed number of 'grades' then this will work. However, I would strongly recommend doing this type of work on the server where possible.
Here we go...
I created two datasets
dsGradeRange with the following sql to recreate your example (more or less)
DECLARE #t TABLE (low int, high int, comment varchar(20))
INSERT INTO #t VALUES
(0,49,'Bad'),
(50,69,'Good'),
(70,100, 'Excellent')
SELECT * FROM #t
dsRandomNumbers This just creates 30 random numbers between 0 and 100
SELECT *
FROM (SELECT top 30 ABS(CHECKSUM(NEWID()) % 100) as myNumber FROM sys.objects) x
ORDER BY myNumber
I added a table to the report to show the grades (just for reference).
I then added a table to show the dsRandomNumbers
Finally I set the expression of the 2nd column to the following expression.
=SWITCH
(
Fields!myNumber.Value < LOOKUP("Bad", Fields!comment.Value, Fields!high.Value, "dsGradeRange"), "Bad",
Fields!myNumber.Value < LOOKUP("Good", Fields!comment.Value, Fields!high.Value, "dsGradeRange"), "Good",
True, "Excellent"
)
This gives the following results
As you can see we only need to compare to the high value of each case, the first match will return the correct comment.
Right click on your dataset and add a calculated field. Go to Field Properties > Fields > Add and add the following expression, which descripes your scenario:
=IIF(Fields!Number.Value < 50, "Bad", "Good")
I have a MySQL view called Balance created from 2 tables order and income with PHPMyAdmin and contains some calculated fields ex: CustomerBalance the decimal place become automatically 8, I mean the field Type is decimal(50,8)
How can i make it 2 only ?
You can use truncate
SELECT TRUNCATE(1.999,2);
return 1.99
select TRUNCATE(your_column,2) from your_table;
In the select list where you calculate the CustomerBalance expression, explicitly truncate or round (depending on your requirements) the result to 2 digits:
select ... round(..., 2) as CustomerBalance ...
Hey is there any way to create query with simple formula ?
I have a table data with two columns value_one and value_two both are decimal values. I want to select this rows where difference between value_one and value_two is grater then 5. How can i do this?
Can i do something like this ?
SELECT * FROM data WHERE (MAX(value_one, value_two) - MIN(value_one, value_two)) > 5
Example values
value_one, value_two
1,6
9,3
2,3
3,2
so analogical difs are: 5, 6, 1, 1 so the selected row would be only first and second.
Consider an example where smaller number is subtracted with a bigger number:
2 - 5 = -3
So, the result is a difference of two numbers with a negation sign.
Now, consider the reverse scenario, when bigger number is subtracted with the smaller number:
5 - 2 = 3
Pretty simple right.
Basically, the difference of two number remains same, if you just ignore the sign. This is in other words called absolute value of a number.
Now, the question arises how to find the absolute value in MySQL?
Answer to this is the built-in method of MySQL i.e. abs() function which returns an absolute value of a number.
ABS(X):
Returns the absolute value of X.
mysql> SELECT ABS(2);
-> 2
mysql> SELECT ABS(-32);
-> 32
Therefore, without worrying about finding min and max number, we can directly focus on the difference of two numbers and then, retrieving the absolute value of the result. Finally, check if it is greater than 5.
So, the final query becomes:
SELECT *
FROM data
WHERE abs(value_one - value_two) > 5;
You can also do complex operations once the absolute value is calculated like adding or dividing with the third value. Check the code below:
SELECT *
FROM
data
WHERE
(abs(value_one - value_two) / value_three) + value_four > 5;
You can also add multiple conditions using logical operators like AND, OR, NOT to do so. Click here for logical operators.
SELECT *
FROM
data
WHERE
((abs(value_one - value_two) / value_three) + value_four > 5)
AND (value_five != 0);
Here is the link with various functions available in MySQL:
https://dev.mysql.com/doc/refman/5.0/en/mathematical-functions.html
No, you would just use a simple where clause:
select *
from data
where abs(value_one - value_two) > 5;
I'm having trouble with this SQL:
$sql = mysql_query("SELECT $menucompare ,
(COUNT($menucompare ) * 100 / (SELECT COUNT( $menucompare )
FROM data WHERE $ww = $button )) AS percentday FROM data WHERE $ww >0 ");
$menucompare is table fields names what ever field is selected and contains data bellow
$button is the week number selected (lets say week '6')
$ww table field name with row who have the number of week '6'
For example, I have data in $menucompare like that:
123456bool
521478bool
122555heel
147788itoo
and I want to select those, who have same word in the last of the data and make percentage.
The output should be like that:
bool -- 50% (2 entries)
heel -- 25% (1 entry)
itoo -- 25% (1 entry)
Any clearness to my SQL will be very appreciated.
I didn't find anything like that around.
Well, keeping data in such format probably not the best way, if possible, split the field into 2 separate ones.
First, you need to extract the string part from the end of the field.
if the length of the string / numeric parts is fixed, then it's quite easy;
if not, you should use regular expressions which, unfortunately, are not there by default with MySQL. There's a solution, check this question: How to do a regular expression replace in MySQL?
I'll assume, that numeric part is fixed:
SELECT s.str, CAST(count(s.str) AS decimal) / t.cnt * 100 AS pct
FROM (SELECT substr(entry, 7) AS str FROM data) AS s
JOIN (SELECT count(*) AS cnt FROM data) AS t ON 1=1
GROUP BY s.str, t.cnt;
If you'll have regexp_replace function, then substr(entry, 7) should be replaced to regexp_replace(entry, '^[0-9]*', '') to achieve the required result.
Variant with substr can be tested here.
When sorting out problems like this, I would do it in two steps:
Sort out the SQL independently of the presentation language (PHP?).
Sort out the parameterization of the query and the presentation of the results after you know you've got the correct query.
Since this question is tagged 'SQL', I'm only going to address the first question.
The first step is to unclutter the query:
SELECT menucompare,
(COUNT(menucompare) * 100 / (SELECT COUNT(menucompare) FROM data WHERE ww = 6))
AS percentday
FROM data
WHERE ww > 0;
This removes the $ signs from most of the variable bits, and substitutes 6 for the button value. That makes it a bit easier to understand.
Your desired output seems to need the last four characters of the string held in menucompare for grouping and counting purposes.
The data to be aggregated would be selected by:
SELECT SUBSTR(MenuCompare, -4) AS Last4
FROM Data
WHERE ww = 6
The divisor in the percentage is the count of such rows, but the sub-stringing isn't necessary to count them, so we can write:
SELECT COUNT(*) FROM Data WHERE ww = 6
This is exactly what you have anyway.
The divdend in the percentage will be the group count of each substring.
SELECT Last4, COUNT(Last4) * 100.0 / (SELECT COUNT(*) FROM Data WHERE ww = 6)
FROM (SELECT SUBSTR(MenuCompare, -4) AS Last4
FROM Data
WHERE ww = 6
) AS Week6
GROUP BY Last4
ORDER BY Last4;
When you've demonstrated that this works, you can re-parameterize the query and deal with the presentation of the results.
Let's say I have a list of values, like this:
id value
----------
A 53
B 23
C 12
D 72
E 21
F 16
..
I need the top 10 percent of this list - I tried:
SELECT id, value
FROM list
ORDER BY value DESC
LIMIT COUNT(*) / 10
But this doesn't work. The problem is that I don't know the amount of records before I do the query. Any idea's?
Best answer I found:
SELECT*
FROM (
SELECT list.*, #counter := #counter +1 AS counter
FROM (select #counter:=0) AS initvar, list
ORDER BY value DESC
) AS X
where counter <= (10/100 * #counter);
ORDER BY value DESC
Change the 10 to get a different percentage.
In case you are doing this for an out of order, or random situation - I've started using the following style:
SELECT id, value FROM list HAVING RAND() > 0.9
If you need it to be random but controllable you can use a seed (example with PHP):
SELECT id, value FROM list HAVING RAND($seed) > 0.9
Lastly - if this is a sort of thing that you need full control over you can actually add a column that holds a random value whenever a row is inserted, and then query using that
SELECT id, value FROM list HAVING `rand_column` BETWEEN 0.8 AND 0.9
Since this does not require sorting, or ORDER BY - it is O(n) rather than O(n lg n)
You can also try with that:
SET #amount =(SELECT COUNT(*) FROM page) /10;
PREPARE STMT FROM 'SELECT * FROM page LIMIT ?';
EXECUTE STMT USING #amount;
This is MySQL bug described in here: http://bugs.mysql.com/bug.php?id=19795
Hope it'll help.
I realize this is VERY old, but it still pops up as the top result when you google SQL limit by percent so I'll try to save you some time. This is pretty simple to do these days. The following would give the OP the results they need:
SELECT TOP 10 PERCENT
id,
value
FROM list
ORDER BY value DESC
To get a quick and dirty random 10 percent of your table, the following would suffice:
SELECT TOP 10 PERCENT
id,
value
FROM list
ORDER BY NEWID()
I have an alternative which hasn't been mentionned in the other answers: if you access from any language where you have full access to the MySQL API (i.e. not the MySQL CLI), you can launch the query, ask how many rows there will be and then break the loop if it is time.
E.g. in Python:
...
maxnum = cursor.execute(query)
for num, row in enumerate(query)
if num > .1 * maxnum: # Here I break the loop if I got 10% of the rows.
break
do_stuff...
This works only with mysql_store_result(), not with mysql_use_result(), as the latter requires that you always accept all needed rows.
OTOH, the traffic for my solution might be too high - all rows have to be transferred.