{"id":27314,"date":"2018-09-05T07:29:50","date_gmt":"2018-09-05T07:29:50","guid":{"rendered":"https:\/\/data-flair.training\/blogs\/?p=27314"},"modified":"2021-03-12T13:14:11","modified_gmt":"2021-03-12T07:44:11","slug":"count-function-in-sql-server","status":"publish","type":"post","link":"https:\/\/data-flair.training\/blogs\/count-function-in-sql-server\/","title":{"rendered":"COUNT Function in SQL Server – Applications & Parameters"},"content":{"rendered":"

In this tutorial, we will understand in detail the aggregate function Count in SQL. Let us now try to learn more about the count function with examples.<\/p>\n

What are the Aggregate Functions in SQL?<\/h3>\n

Aggregate functions are used over a set of values, which in return comes down to a single value.<\/p>\n

Count function in SQL is deterministic in nature i.e. no matter how many times it is run, the answer remains the same until the contents of the table are modified.<\/p>\n

Count function doesn\u2019t ignore the NULL values in the database and considers them too while calculating the result of the query.<\/p>\n

In SQL we have various Aggregate functions like:<\/p>\n\n\n\n\n\n\n\n\n\n
Sr.No<\/b><\/td>\nFunction<\/b><\/td>\nDescription<\/b><\/td>\n<\/tr>\n
1<\/td>\nAVG()<\/td>\nReturns the average value.<\/span><\/td>\n<\/tr>\n
2<\/td>\nCOUNT()<\/td>\nReturns the count.<\/span><\/td>\n<\/tr>\n
3<\/td>\nMAX()<\/td>\nReturns the maximum out of the given values.<\/span><\/td>\n<\/tr>\n
4<\/td>\nMIN()<\/td>\nReturns the minimum out of the given values.<\/span><\/td>\n<\/tr>\n
5<\/td>\nSUM()<\/td>\nReturns the sum of the given values.<\/span><\/td>\n<\/tr>\n
6<\/td>\nVAR()<\/td>\nReturns variance of the given values.<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

Where do we use Count in SQL?<\/h3>\n

We use the count function when we need to get the count of something. For example:<\/p>\n

1. COUNT(*):<\/strong> Returns the total records in the table.
\nSyntax:<\/p>\n

SELECT col1,\r\nCol2, COUNT(*) AS col_count,\r\nFROM tableName;\r\n<\/pre>\n
2. COUNT(columnName):<\/strong> Returns the total number of records(Includes the Null values also) in the columnName.
\nSyntax:<\/p>\n
SELECT col1,col2,.......,\r\nCOUNT(colName) AS col_count \r\nFROM tableName;\r\n<\/pre>\n
3. COUNT(DISTINCT columnName):<\/strong> Returns the count of unique records in the columnName.
\nSyntax:<\/p>\n
SELECT col1,col2,....,\r\nCOUNT(DISTINCT colName) AS colDistinctCount \r\nFROM tableName;\r\n<\/pre>\n
Demo DataBase<\/h3>\n
Let us now view our demo database and understand it\u2019s contents.
\nQuery:\u00a0<\/strong><\/p>\n
SELECT * FROM DataFlair;\r\n<\/pre>\n
Output:<\/strong><\/p>\n
\"SQL<\/a><\/p>\n
In our DataFlair database, we have five columns indicating the details of employees at DataFlair. The columns available are as follows:<\/p>\n