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How to count number of occurrences for all different values in database column?

开发者 https://www.devze.com 2022-12-30 16:57 出处:网络
I have a Postgre database that has say 10 columns. The fifth column is called column5. There are 100 rows in the database and possible values of column5 are c5value1, c5value2, c5value3...c5value29, c

I have a Postgre database that has say 10 columns. The fifth column is called column5. There are 100 rows in the database and possible values of column5 are c5value1, c5value2, c5value3...c5value29, c5value30. I would like to print out a table that shows how many times each value occurs.

So the table would look like this:

Value(of column5)          number of occurrences of the value
     c5value1                       开发者_StackOverflow中文版       1
     c5value2                              5
     c5value3                              3
     c5value4                              9
     c5value5                              1
     c5value6                              1
        .                                  .
        .                                  .
        .                                  .

What is the command that does that?


Group by the column you are interested in and then use count to get the number of rows in each group:

SELECT column5, COUNT(*)
FROM table1
GROUP BY column5


Use the GROUP BY clause and the COUNT() aggregate function:

SELECT column5, COUNT(column5) AS Occurences
FROM myTable
GROUP BY column5
0

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