Hey, folks! In this article, we will be focusing on SQL SELECT statement along with COUNT() function.
What is SQL SELECT statement?
SQL SELECT statement helps us select and display the data values from the particular table of the database.
Syntax:
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SELECT columns FROM Table-name; |
Example:
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SELECT * from Info; |
SELECT * statement helps select all the data values from the provided table.
Output:
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id Cost city 1 100 Pune 2 100 Satara 3 65 Pune 4 97 Mumbai 5 12 USA |
What is SQL COUNT() function?
SQL COUNT() function counts the total number of rows present in the database.
Syntax:
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COUNT(column-name) |
Example:
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SELECT Count(City) from Info; |
In this example, we have displayed the count of all the data rows under the column – ‘city’ of table – ‘Info’.
Output:
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5 |
Variations of SQL SELECT statement with COUNT() function
You can use the SQL SELECT statement with the COUNT() function to select and display the count of rows in a table of a database.
Along with this, we can club SQL SELECT statement with COUNT() function in various different ways.
Having understood the working of SQL SELECT COUNT(), let us now understand different variations associated with the same through examples.
Examples of SQL SELECT with COUNT() function
To display the variations in SQL SELECT COUNT(), we have used SQL CREATE query to create a Table and SQL INSERT query to input data to the database.
We will be using the below table and its data in the further examples.
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create table Info(id integer, Cost integer, city varchar(200)); insert into Info(id, Cost,city) values(1, 100,"Pune"); insert into Info(id, Cost,city) values(2, 100, "Satara"); insert into Info(id, Cost,city) values(3, 65,"Pune"); insert into Info(id, Cost,city) values(4, 97,"Mumbai"); insert into Info(id, Cost,city) values(5, 12,"USA"); select * from Info; |
Output:
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id Cost city 1 100 Pune 2 100 Satara 3 65 Pune 4 97 Mumbai 5 12 USA e |
1. SQL SELECT COUNT with WHERE clause
SQL SELECT COUNT() can be clubbed with SQL WHERE clause.
Using the WHERE clause, we have access to restrict the data to be fed to the COUNT() function and SELECT statement through a condition.
Example:
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SELECT COUNT(city) FROM Info WHERE Cost>50; |
Output:
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3 |
2. SQL SELECT COUNT(*) function
SQL SELECT statement can be used along with COUNT(*) function to count and display the data values.
The COUNT(*) function represents the count of all rows present in the table (including the NULL and NON-NULL values).
Example:
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SELECT COUNT(*) FROM Info; |
Output:
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5 |
3. SQL SELECT COUNT with DISTINCT clause
The DISTINCT clause helps exclude the redundant data and displays only the unique values from the selected column.
SQL SELECT COUNT() function can be used along with DISTINCT clause to count and display the number of rows representing unique(non-repeated) values.
Example:
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SELECT COUNT(DISTINCT Cost) FROM Info; |
Output:
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4 |
4. SQL SELECT COUNT with HAVING and GROUP BY clause
SQL SELECT COUNT() function can be clubbed with GROUP BY and HAVING clause to add conditions before the selection of data as well as grouping of data rows by a particular column value.
Example:
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SELECT city, COUNT(Cost) FROM Info GROUP BY city HAVING COUNT(Cost)>1; |
Output:
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city COUNT(Cost) Pune 2 |
Conclusion
By this, we have come to an end of this topic. Please feel free to comment below in case you come across any doubt.
For more such posts related to SQL, please do visit SQL JournalDev.