I have a column that is currently a floating-point number and I need to check if all the values in the column are integers. What's the easiest way to do this?
SELECT COUNT(*) FROM yourtable WHERE ceil(yourcolumn) != yourcolumn
If the count > 0 then there are non-integer values.
And to specifically find the records that are not integers...
SELECT * from yourtable WHERE col % 1 != 0;
Related
I have the following query that helps me count how many null values were reported in each column across all columns of a table in BQ:
SELECT col_name, COUNT(1) nulls_count
FROM table t,
UNNEST(REGEXP_EXTRACT_ALL(TO_JSON_STRING(t), r'"(\w+)":null')) col_name
GROUP BY col_name
;
I need to adjust it so it counts the non-null values. I tried to use negative lookahead but it doesn't seem to work.
My end goal is to indicate wether a certain column reports at least 1 non-null value.
Input example (the table):
Output example:
column_c is not present since all of its values are nulls.
You can try this, (without REGEX) solution
select * from (select column, countif(val!= 'null') non_null
from `dataset.table` table1
,unnest(array(
select as struct trim(ar[offset(0)], '"') column, trim(ar[offset(1)], '"') val
from unnest(split(trim(to_json_string(table1), '{}'))) pb,
unnest([struct(split(pb, ':') as ar)])
)) record
group by column) where non_null!=0
output:
How do I select a value range from a column where two values in it are separated by a dash, using MySQL?
Here's my example table named "example":
The user enters a low value (X) and a high value (Y).
For example X=2.5 and Y=7.2
I want to select all items where the left value is higher than X (in this case 2.5) and the right value is lower than Y (in this case 7.2). Using these X and Y values I should end up with the rows 2 and 5 as a result.
Sort of like this:
SELECT * FROM example WHERE MIN(value) > X AND MAX(value) < Y
How do I do this?
You can use LEFT and RIGHT functions to get X and Y out of your value field.
So I think you are looking for something like this:
SELECT * FROM example WHERE CAST(LEFT(value,3)AS DECIMAL(2,1)) > 2.5 and CAST(RIGHT(value,3)AS DECIMAL(2,1)) < 7.2
First you need to access your table in a fashion that only has one value per column. (Multiple values per column, like 3.5-7.5 happen to be a very common relational database design antipattern. They cripple both performance and clarity.)
This SQL subquery does the trick for pairs of values.
SELECT item_id, name,
0.0+SUBSTRING_INDEX(value, '-',1) first,
0.0+SUBSTRING_INDEX(value, '-', -1) last
FROM example;
The expression 0.0+something is a MySQL trick to coerce a value to be numeric.
Then use the subquery to apply your search criteria.
SELECT item_id, name, first, last
FROM ( SELECT item_id, name,
0.0+SUBSTRING_INDEX(value, '-',1) first,
0.0+SUBSTRING_INDEX(value, '-', -1) last
FROM example
) s
WHERE first > 2.5
AND last < 7.2;
Fiddle here.
In a comment you asked about the situation where you have more than two values in a single column separated by delimiters. See this. Split comma separated values in MySQL
Pro tip Don't put more than one number in a column in an RDBMS table. The next person to use the table will be muttering curses all day while trying to use that data.
Pro tip Use numeric data types, not VARCHAR(), for numbers.
I need to get maximum number from a part of the value that generally start with year followed by slash(/). So I need a maximum number after the slash(/) but year should be 2016
2016/422
2016/423
2016/469
2016/0470
2014/777
2015/123
2015/989
I tried this query
SELECT columname FROM tablename WHERE columname LIKE '2016/%' ORDER BY id DESC
the above query always giving '2016/469' as first record, how to get '2016/0470' as the maximum number?
any help will be much appreciated.
Thank you.
If columname follows that pattern YEAR/0000, you can use SUBSTRING function from MySQL to remove the part of the string you don't want.
SELECT value FROM (
SELECT CAST(SUBSTRING(columname, 0, 4) AS UNSIGNED) as year, CAST(SUBSTRING(columname FROM 6) AS UNSIGNED) as value FROM tablename
) total
ORDER BY year DESC, value DESC
LIMIT 1;
You need to split the string into 2 parts and evaluate them as numbers, instead of strings. The following formula will return the number after the / in the fieldname. All functions used below are described in the string functions section of the MySQL documentation. This way you can get the number after the / character, even if it is not year before the /, but sg else. The + 0 converts the string to a number, eliminating any leading 0.
select right(columnname, char_length(columnname)-locate('/',columnname)) + 0
from tablename
Just take the max() of the above expression to get the expected results.
UPDATE:
If you need the original number and the result has to be restricted to a specific year, then you need to join back the results to the original table:
select columnname
from tablename t1
inner join (select max(right(t.columnname, char_length(t.columnname)-locate('/',t.columnname)) + 0) as max_num
from tablename t
where left(t.columnname,4)='2016'
) t2
on right(t1.columnname, char_length(1t.columnname)-locate('/',t1.columnname)) + 0 = t2.max_num
where left(t1.columnname,4)='2016'
There are lots of suggestions given as answers already. But some of those seem overkill to me.
Seems like the only change needed to the OP query is the expression in the ORDER BY clause.
Instead of:
ORDER BY id
We just need to order by the numeric value following the slash. And there are several approaches, several expressions, that will get that from the example data.
Since the query already includes a condition columname LIKE '2016/%'
We can get the characters after the first five characters, and then convert that string to a numeric value by adding zero.
ORDER BY SUBSTRING(columname,6) + 0 DESC
If we only want to return one row, add
LIMIT 1
http://dev.mysql.com/doc/refman/5.7/en/string-functions.html#function_substring
If we only want to return the numeric value, we could use the same expression in the SELECT list, in addition columnname.
This isn't the only approach. There are lots of other approaches that will work, and don't use SUBSTRING.
Try like this:
SELECT
MAX(CAST(SUBSTRING(t.name,
LOCATE('/', t.name) + 1)
AS UNSIGNED)) AS max_value
FROM
tablename AS t;
You can try with this little uggly approach:
SELECT t.id, t2.secondNumber FROM table AS t
JOIN (SELECT id,
CONCAT(SUBSTRING(field,1,5),
if(SUBSTRING(SUBSTRING(field, 6),1,1)='0',
SUBSTRING(field, 6),
SUBSTRING(field,7)
)
) as secondNumber FROM table ) AS t2 ON t2.id=t.id
ORDER BY t2.secondNumber DESC
Would be valid only if the 0 (zeroes) before the second number (after the slash) are no more than 1.
Or if the year doesn`t matter you can try to order them only by the second number if it is ok:
SELECT t.id, t2.secondNumber FROM table AS t
JOIN (SELECT id,
if(SUBSTRING(SUBSTRING(field, 6),1,1)='0',
SUBSTRING(field, 6),
SUBSTRING(field,7)
) as secondNumber FROM table ) AS t2 ON t2.id=t.id
ORDER BY t2.secondNumber DESC
I want to calculate percentage for test groups.
I have group A,B and C. And I want to know how much success percentage each group have.
My first query is counting total test ran in each group by doing the following:
SELECT type, count(type) as total_runs
From mytable
Where ran_at > '2015-09-11'
Group by type
Second query is counting success for each group:
SELECT type, count(type) as success
FROM mytable
where run_status like '%success%' and ran_at> '2015-09-11'
Group by type
Now I need to divide one in the other and multiply in 100.
how do I do this in one query in an efficient way, I guess nested query is not so efficient- but anyway I can't see how I can uses nested query to solve it.
I would appreciate answer which include simple way, maybe not so efficient, and an efficient way with explanations
You can just use conditional aggregation:
SELECT type, sum(run_status like '%success%') as success,
100 * avg(run_status like '%success%') as p_success
FROM mytable
where ran_at> '2015-09-11'
Group by type;
In a numeric context, MySQL treats boolean expressions as integers with 1 for true and 0 for false. The above works assuming that run_status is not NULL. If it can be NULL, then you need an explicit case statement for the avg().
I had this one, but Gordon have a better solution if run_status is not NULL.
Select type, sum(if(run_status like '%success%',1,0)) / count(1) * 100) as p_success
From mytable
Where ran_at > '2015-09-11'
Group by type
I need to perform an avg on a column, but I know that most of the values in that column will be zero. Out of all possible rows, only two will probably have positive values. How can I tell mySQL to ignore the zeros and only average the actual values?
Assuming that you might want to not totally exclude such rows (perhaps they have values in other columns you want to aggregate)
SELECT AVG(NULLIF(field ,0))
from table
You could probably control that via the WHERE clause:
select avg( field ) from table where field > 0
select avg(your_column)
from your_table
where your_column != 0
You can convert zeros to NULL, then AVG() function will work only with not NULL values.
UPDATE table SET column = NULL WHERE column='0';
SELECT AVG(column) FROM table;