Having (SQL)
A codice_1 clause in SQL specifies that an SQL codice_2 statement must only return rows where aggregate values meet the specified conditions. codice_1 and codice_4 are often confused by beginners, but they serve different purposes. codice_4 is taken into account at an earlier stage of a query execution, filtering the rows read from the tables. If a query contains codice_6, rows from the tables are grouped and aggregated. After the aggregating operation, codice_1 is applied, filtering out the rows that don't match the specified conditions. Therefore, codice_4 applies to data read from tables, and codice_1 should only  apply to aggregated data, which isn't known in the initial stage of a query. To view the present condition formed by the codice_6 clause, the codice_1 clause is used. Examples. To return a list of department IDs whose total sales exceeded $1000 on the date of January 1, 2000, along with the sum of their sales on that date: SELECT DeptID, SUM(SaleAmount) FROM Sales WHERE SaleDate = '01-Jan-2000' GROUP BY DeptID HAVING SUM(SaleAmount) > 1000 Referring to the sample tables in the "Join" example, the following query will return the list of departments which have more than  1 employee: SELECT DepartmentName, COUNT(*) FROM Employee JOIN Department ON Employee.DepartmentID = Department.DepartmentID GROUP BY DepartmentName HAVING COUNT(*)>1; codice_1 is convenient, but not necessary. Code equivalent to the example above, but without using codice_1, might look like: SELECT * FROM ( ) AS grp WHERE grp.empCnt > 1;