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Tag: sql

How to count number of groups?

I have a table as follow: I want to count the number of distinct g_n. (Here it’s 3.) I have tried with: But it gives me the number of items per group. How can I count the number of distinct g_n? Answer Use count(distinct): There is no need to aggregate using group by for this result. Note: This ignores NULL

JOIN with OR condition and use only MIN(Column)

I have two tables. Certain values from table t need to be matched with certain values of table m in order to identify a target value from table m. Table t looks as follows. Table m looks as follows. The logic should be as follows: Column A from table t should be matched with column matchA from table m and

SQL many joins many to many

I have 5 tables: Table Reports Many to many table ReportsIpRel Table of InfoProviders Many to many table QueriesIpRel And table of Queries The SELECT I am trying to achieve is the following: I tried many left/inner joins like this: but all for nothing. I have to use where condition: WHERE report_Id = ‘2’ /EXAMPLE I’m trying to do this

using ORDER BY in SQL for chunks of data

I want to know how I sort data in a SQL query but only in certain chunks. I’ll provide an example to make it easier. In the above example, I want to do an ORDER BY height DESC, BUT only the tallest person of each rank gets ordered and everyone else in the same rank is right under that person

Anyway to add a constraint when using SQL count

I want to to use count to include a criteria where patient doesn’t have diabetetes, and then using the query to show country that has at least 3 patients that doesn’t have diabetes How shoudl I be doing this? How can I include a constraint when using count? yeah I think this should work, basically my logic is not every

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