SQL COUNT function belongs to Aggregate functions and it is one of the most easy-to-use and also most used functions of SQL. It enables user to count rows in certain column or rows in whole table.
(!!!) NULL records are missed out if we count number of records above certain column using sql COUNT.
SQL COUNT function Syntax and Examples
1 Number of rows in whole table:
SELECT COUNT(*) AS Row_Count
Returns count of all records in the table where at least 1 column value is non-empty
2 Number of records with non-empty value in selected column:
SELECT COUNT(Column) AS Number_of_non-empty_rows
Returns number of non-empty (NOT NULL) values above the column “Column”
3 Agregated number of all records in the table through certain fields:
SELECT Column, COUNT(*) AS Row_Count_by_Column
GROUP BY Column
Returns aggregated number of records through all unique values of “Column” field. Clause GROUP BY is mandatory in this case.