Use of SELECT Statements in Views in Oracle

Q

Can SELECT Statements Be Used on Views in Oracle?

✍: FYIcenter.com

A

Select (query) statements can used on views in the same way as tables. The following tutorial exercise helps you creating a view and running a query statement on the view:

SQL> CREATE VIEW managed_dept AS 
  SELECT * FROM departments WHERE manager_id IS NOT NULL;
View created.

SQL> SELECT * FROM managed_dept WHERE location_id = 1700;
DEPARTMENT_ID DEPARTMENT_NAME      MANAGER_ID LOCATION_ID
------------- -------------------- ---------- -----------
           10 Administration              200        1700
           30 Purchasing                  114        1700
           90 Executive                   100        1700
          100 Finance                     108        1700
          110 Accounting                  205        1700

⇒ Filter Out Duplications in Returning Rows in Oracle

⇐ Count the Number of Rows with SELECT Statements in Oracle

⇑ Understanding SQL SELECT Query Statements in Oracle

⇑⇑ Oracle Database Tutorials

2019-12-19, 2924🔥, 0💬

Count the Number of Rows with SELECT Statements in Oracle
How To Use SELECT Statement to Count the Number of Rows in Oracle? If you want to count the number of rows, you can use the COUNT(*) function in the SELECT clause. The following select statement returns the number of rows in the "department" table: SQL> SELECT COUNT(*) FROM departments; COUNT... 2019-12-19, 3465🔥, 0💬

Select Some Rows from a Table in Oracle
How To Select Some Rows from a Table in Oracle? If you don't want select all rows from a table, you can specify a WHERE clause to tell the query to return only the rows that meets the condition defined in the WHERE clause. The following select statement only returns rows that has department name sta... 2019-12-19, 3460🔥, 0💬

Group Functions Used with Non-group Selection Fields in Oracle
Can Group Functions Be Mixed with Non-group Selection Fields in Oracle? If a group function is used in the SELECT clause, all other selection fields must be group level fields. Non-group fields can not be mixed with group fields in the SELECT clause. The script below gives you an example of invalid ... 2019-11-21, 3315🔥, 0💬

Sort Query Output in Descending Order in Oracle
How To Sort Query Output in Descending Order in Oracle? If you want to sort a column in descending order, you can specify the DESC keyword in the ORDER BY clause. The following SELECT statement first sorts the department in descending order, then sorts the salary in ascending order: SQL> SELE... 2019-12-19, 3186🔥, 0💬

Sort the Query Output in Oracle
How To Sort the Query Output in Oracle? If you want the returning rows to be sorted, you can specify a sorting expression in the ORDER BY clause. The following select statement returns rows sorted by the values in the "manager_id" column: SQL> SELECT * FROM departments ORDER BY manager_id; DE... 2019-12-19, 3118🔥, 0💬

What Are Group Functions in Oracle
What Are Group Functions in Oracle? Group functions are functions applied to a group of rows. Examples of group functions are: COUNT(*) - Returns the number of rows in the group. MIN(exp) - Returns the minimum value of the expression evaluated on each row of the group. MAX(exp) - Returns the maximum... 2019-12-19, 3041🔥, 0💬

Filter Out Duplications in Returning Rows in Oracle
How To Filter Out Duplications in Returning Rows in Oracle? If there are duplications in the returning rows, and you want to remove the duplications, you can use the keyword DISTINCT or UNIQUE in the SELECT clause. The tutorial exercise below shows you that DISTINCT works on selected columns only: S... 2019-12-19, 2995🔥, 0💬

Use Group Functions in the SELECT Clause in Oracle
How To Use Group Functions in the SELECT Clause in Oracle? If group functions are used in the SELECT clause, they will be used on the rows that meet the query selection criteria, the output of group functions will be returned as output of the query. The following select statement returns 4 values ca... 2019-11-21, 2993🔥, 0💬

Query Output Sorted by Multiple Columns in Oracle
Can the Query Output Be Sorted by Multiple Columns in Oracle? You can specifying multiple columns in the ORDER BY clause as shown in the following example statement, which returns employees' salaries sorted by department and salary value: SQL> SELECT department_id, first_name, last_name, sala... 2019-12-19, 2934🔥, 0💬

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