55 lines
2.3 KiB
Markdown
55 lines
2.3 KiB
Markdown
---
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title: SQL COUNT Aggregate Function
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---
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## SQL COUNT Aggregate Function
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The COUNT operator is usually used in combination with a GROUP BY clause. It is one of the SQL "aggregate" functions, which include AVG (average) and SUM.
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This function will count the number of rows and return that count as a column in the result set.
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Here are examples of what you would use COUNT for:
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* Counting all rows in a table (no group by required)
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* Counting the totals of subsets of data (requires a Group By section of the statement)
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For reference, here is the current data for all the rows in our example student database.
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```sql
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select studentID, FullName, programOfStudy, sat_score from student; -- all records with fields of interest
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```
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This SQL statement provides a count of all rows. Note that you can give the resulting COUNT column a name using "AS".
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```sql
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select count(*) AS studentCount from student; -- count of all records
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```
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Here we get a count of students in each field of study.
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```sql
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select programOfStudy, count(*) AS studentCount from the student table with a group by programOfStudy;
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```
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Here we get a count of students with the same SAT scores.
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```sql
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select sat_score, count(*) AS studentCount from the student table with a group by sat_score;
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```
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Here is an example using the campaign funds table. This is a sum total of the dollars in each transaction and the number of contributions for each political party during the 2016 US Presidential Campaign.
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```sql
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select Specific_Party, Election_Year, format(sum(Total_$),2) AS contribution$Total, count(*) AS numberOfContributions
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from combined_party_data
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group by Specific_Party,Election_Year
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having Election_Year = 2016;
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```
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As with all of these things there is much more to it, so please see the manual for your database manager and have fun trying different tests yourself.
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