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A HAVING clause in SQL specifies that an SQL SELECT statement should only return rows where aggregate values meet the specified conditions. It was added to the SQL language because the WHERE keyword could not be used with aggregate functions.〔(【引用サイトリンク】title=SQL HAVING Clause )〕== 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, Department WHERE Employee.DepartmentID = Department.DepartmentID GROUP BY DepartmentName HAVING COUNT( *)>1; HAVING is convenient, but not necessary. Code equivalent to the example above, but without using HAVING, might look like:SELECT * FROM ( SELECT DepartmentName AS deptNam, COUNT( *) AS empCnt FROM Employee AS emp, Department AS dept WHERE emp.DepartmentID = dept.DepartmentID GROUP BY deptNam ) AS grp WHERE grp.empCnt > 1; 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Having (SQL)」の詳細全文を読む スポンサード リンク
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