Best way to compare three columns in sql Hive - sql

I need to do some comparison through 3 columns containing string dates 'yyyy-mm-dd', in Hive SQL. Please take in consideration that the table has more than 2 million records.
Consider three columns (col1; col2; col3) from table T1, I must guarantee that:
col1 = col2, and both, or at least one is different from col3.
My best regards,

Logically you have an issue.
col1 = col2
Therefore if col1 != col3 then col2 != col3;
There for it's really enough to use:
select * from T1 where col1 = col2 and col1 != col3;
It is appropriate to do this map side so using a where criteria is likely good enough.
If you wanted to say 2 out of the 3 need to match you could use group by with having to reduce comparisons.

Related

Insert Statement for List

I'm not too sure how to describe my SQL Insert statement so I will describe the expected result.
I'm building a data extract list and have a table that I've put all my data into. It's called _MATTER_LIST
What I am trying to Achieve is to have the Client_Number + Col1 combination repeat after every unique COL1+COL2+COL3 combination but not duplicate when there is already a CLIENT_NUMBER+COL1. So the end result would be:
thanks in advance for any tips.
Simple ORDER BY should work for you if i understand. Try this :
select Client_Number, Col1, Col2, Col3 from _MATTER_LIST
order by Client_Number, Col1
I've managed to fix my own issue. I added a unique key for the col1 + col2 + col3 , then make col2 repeat over each combination for example.
The result is: select * from _MATTER_LIST order by COL4, COL5

Reject a row based on 2 column values

Below is the output of a simple join query. All the 3 columns are from different tables.
Col1 Col2 Col3
Manual Y-Yes Include
MC Y-Yes Include
Manual Y-Yes Exclude
Manual Y-Yes Exclude
I need to get the rows with 'Include' only if there is no 'Exclude' for the same Col1 value.
If there is no 'Exclude' for the Col1 value, then its fine to display 'Include'.
So the query should not display the first row according to the requirement since the Col1 value 'Manual' has 'Exclude'.
Your sql query should look a lot like what your question would be in English:
You want all the rows where there is no row for the same col1 value that has 'Exclude' in the col3 value, right?
I cannot give exact sql since you do not provide table or column names, but if all three columns were in the same table, it would look like this:
Select * from mytable
where not exists
(select * from mytable
where col1 = t.col1
and col3 = 'Exclude')

query to find specific word in a cloumn using oracle database

can anyone help me in the below query.
I wanted to find the records which have "word1" in col1 and we can write the below query for that but do we have any other option/operator that we can find the exact word in the col1 without prefix and postfix.
Select col1, col2 from table1
where col1 like '%word1%'
or col1 like '%word1'
or col1 like 'word1%'
or col1 = 'word1';
Note: I know that we can use contains operator but it uses the index which i don't want.
Please let me know is there any other way to represent above quer in a simple manner.
you want something like like .. but why?
If it is for a learning, you can use INSTR()
Select col1, col2 from table1
where INSTR(col1,'word1') > 0
Otherwise best approach is
Select col1, col2 from table1
where col1 like '%word%'

SQL parametrised query containing multiple options

I would like to write a query
Select col1, col2
from table
where col1 = 'blah' or 'blah2' or 'blah3'
and col2 = 'blah' or 'blah2' or 'blah3'
I am used to writing them like this for a SINGLE option
select
col1, col2
from
table
where
col1 = :col1 and col2 = :col2
Parameters.AddWithValue(":col1", 'blah')
Parameters.AddWithValue(":col2", 'blah')
Now I want to add several options with OR between them and obviously the above code wont work. The SQL is for SQLite. Can anyone suggest how I could do this? I may potential have more then 3 different values for each parameter. I have tried searching but the answer is elusive.
You still have to use complete expressions, i.e., you need to write col1 = or col2 = every time.
Alternative, use IN:
SELECT ... WHERE col1 IN (:c11, :c12, :c13) AND col2 IN (:c21, :c22, :c23);

How to generate Dynamic Order by clause in PL/SQL procedure?

I am trying to write a PL/SQL procedure which will have the SQL query to get the results. But the requirement is that the order by can be dynamic and is mainly for sorting the columns in the screen. I am passing 2 parameters to this procedure - in_sort_column and in_sort_order.
The requirement is such that on text columns the sorting is in ASC and for numbers it is DESC.
My query looks something like this without adding the in_sort_order -
SELECT col1, col2, col3 from tabl e1 where col1 > 1000
ORDER BY decode(in_sort_column,'col1', col1, 'col2', col2, 'col3', col3);
I am not able to figure out how to use the in_sort_order parameter in this case. Can someone who has done this before help out ?
Thanks
When doing a dynamic sort, I recommend using separate clauses:
order by (case when in_sort_column = 'col1' then col1 end),
(case when in_sort_column = 'col2' then col2 end),
(case when in_sort_column = 'col3' then col3 end)
This guarantees that you will not have an unexpected problem with type conversion, if the columns are of different types. Note that case return NULL without an else clause.
Since the requirement is based on data type, you could just negate the numeric columns in your decode; if col1 is numeric and the others are text then:
ORDER BY decode(in_sort_column, 'col1', -col1, 'col2', col2, 'col3', col3);
But this is going to attempt to convert the text columns to numbers. You can swap the decode or around to avoid that, but you then do an implicit conversion of your numeric column to a string, and your numbers will then be sorted alphabetically - so 2 comes after 10, for example.
So Gordon Linoff's use of case is better, and you can still negate the col1 value with that to make the numbers effectively sort descending.