Clauses in sql server
Download as DOCX, PDF0 likes363 views
The document discusses various clauses that can be used in SQL SELECT statements, including the WHERE, GROUP BY, HAVING, and ORDER BY clauses. It provides examples of how each clause works and how they can be used together. The WHERE clause filters rows based on conditions. The GROUP BY clause groups rows based on column values. The HAVING clause applies additional filters to groups. And the ORDER BY clause defines the sort order of rows in the results.
![Naveen Kumar Veligeti
CLAUSES in SQL Server
SQL Server provides with the following clauses that can be used in the SELECT statements:
WHERE
GROUP BY
HAVING
ORDER BY
The complete syntax of the SELECT statement looks as following:
SELECT <select_list> FROM <tname>
[ WHERE search_condition ]
[ GROUP BY group_by_expression ]
[ HAVING search_condition ]
[ ORDER BY order_expression [ ASC | DESC ] ]
WHERE Clause:
The WHERE clause is a filter that defines the conditions each row in the source tables must meet
to qualify for the SELECT. Only rows that meet the conditions contribute data to the result set.
Data from rows that do not meet the conditions is not used.
SELECT * FROM EMP WHERE JOB='MANAGER'
SELECT * FROM EMP WHERE DEPTNO=20
GROUP BY Clause:
The GROUP BY clause partitions the result set into groups based on the values in the columns of
the group_by_list. For example, the Emp table has 3 values in Deptno column. A GROUP
BY Deptno clause partitions the result set into 3 groups, one for each value of Deptno.
Ex-1:How to find the highest salaries for each department.
Sol: SELECT DEPTNO, MAX(SAL) FROM EMP GROUP BY DEPTNO
Ex-2:How to find the highest salaries for each job.
Sol: SELECT JOB, MAX(SAL) FROM EMP GROUP BY JOB
1](https://image.slidesharecdn.com/clausesinsqlserver-140204031233-phpapp01/85/Clauses-in-sql-server-1-320.jpg)
![Naveen Kumar Veligeti
ORDER BY order_list[ ASC | DESC ]
SELECT * FROM EMP ORDER BY SAL
SELECT * FROM EMP ORDER BY SAL DESC
SELECT * FROM EMP ORDER BY SAL, COMM
3](https://image.slidesharecdn.com/clausesinsqlserver-140204031233-phpapp01/85/Clauses-in-sql-server-3-320.jpg)
Clauses in sql server
- 1. Naveen Kumar Veligeti CLAUSES in SQL Server SQL Server provides with the following clauses that can be used in the SELECT statements: WHERE GROUP BY HAVING ORDER BY The complete syntax of the SELECT statement looks as following: SELECT <select_list> FROM <tname> [ WHERE search_condition ] [ GROUP BY group_by_expression ] [ HAVING search_condition ] [ ORDER BY order_expression [ ASC | DESC ] ] WHERE Clause: The WHERE clause is a filter that defines the conditions each row in the source tables must meet to qualify for the SELECT. Only rows that meet the conditions contribute data to the result set. Data from rows that do not meet the conditions is not used. SELECT * FROM EMP WHERE JOB='MANAGER' SELECT * FROM EMP WHERE DEPTNO=20 GROUP BY Clause: The GROUP BY clause partitions the result set into groups based on the values in the columns of the group_by_list. For example, the Emp table has 3 values in Deptno column. A GROUP BY Deptno clause partitions the result set into 3 groups, one for each value of Deptno. Ex-1:How to find the highest salaries for each department. Sol: SELECT DEPTNO, MAX(SAL) FROM EMP GROUP BY DEPTNO Ex-2:How to find the highest salaries for each job. Sol: SELECT JOB, MAX(SAL) FROM EMP GROUP BY JOB 1
- 2. Naveen Kumar Veligeti Ex-3:How to find the highest salaries for each department in it for each job. Sol: SELECT DEPTNO, JOB, MAX(SAL) FROM EMP GROUP BY DEPTNO, JOB Note: While using the GROUP By clause the select_list of the query should contain only the following: Group Functions or Aggregate Functions Columns used in the Group By Clause Constants. Ex-4:How to find the number of employees working for each department. Sol: SELECT DEPTNO, COUNT(*) FROM EMP GROUP BY DEPTNO Ex-5:How to find the number of employees working for each department only if the number is greater than 3. Sol: SELECT DEPTNO, COUNT(*) FROM EMP GROUP BY DEPTNO HAVING COUNT(*)>3 HAVING Clause: The HAVING clause is an additional filter that is applied to the result set. Logically, the HAVING clause filters rows from the intermediate result set built from applying any FROM, WHERE, or GROUP BY clauses in the SELECT statement. HAVING clauses are typically used with a GROUP BY clause. Ex-6:How to find the number of Clerk’s working for each department. Sol: SELECT DEPTNO, COUNT(*) FROM EMP WHERE JOB='CLERK' GROUP BY DEPTNO Ex-7:How to find the number of Clerk's working for each department only if the count is greater than 1. Sol: SELECT DEPTNO, COUNT(*) FROM EMP WHERE JOB='CLERK' GROUP BY DEPTNO HAVING COUNT(*)>1 ORDER BY clause: The ORDER BY clause defines the order in which the rows in the result set are sorted. order_list specifies the result set columns that make up the sort list. The ASC and DESC keywords are used to specify if the rows are sorted in an ascending or descending sequence. 2
- 3. Naveen Kumar Veligeti ORDER BY order_list[ ASC | DESC ] SELECT * FROM EMP ORDER BY SAL SELECT * FROM EMP ORDER BY SAL DESC SELECT * FROM EMP ORDER BY SAL, COMM 3