Count(*) and column renaming : Columns « Query Select « Oracle PL/SQL Tutorial





SQL>
SQL>
SQL> create table product(
  2          product_id          integer     primary key
  3          ,price                  number(7,2)
  4          ,description            varchar2(75)
  5          ,onhand                 number(5,0)
  6          ,reorder                number(5,0)
  7          ,supplier_no            integer
  8  );

Table created.

SQL> -- product Table Inserts:
SQL> insert into product(product_id, price, description, onhand, reorder)values (1,2.50,'Happy Birthday',100,20);

1 row created.

SQL> insert into product(product_id, price, description, onhand, reorder)values (2,23.00,'Happy Birthday',null,null);

1 row created.

SQL> insert into product(product_id, price, description, onhand, reorder)values (3,null,'Happy New Year',null,null);

1 row created.

SQL> insert into product(product_id, price, description, onhand, reorder)values (4,1.50,'Happy New Year',50,10);

1 row created.

SQL>
SQL> select count(*) "No. of Products" from product;

No. of Products
---------------
              4

1 row selected.

SQL>
SQL>
SQL> drop table product;

Table dropped.










2.8.Columns
2.8.1.Selecting All Columns from a Table with asterisk character (*)
2.8.2.Count(*) and column renaming
2.8.3.Expression and column renaming
2.8.4.DISTINCT tableName.*
2.8.5.Combined columns and renaming
2.8.6.Format date value and column renaming
2.8.7.Reference one column more than once
2.8.8.Reference renamed column in order by
2.8.9.Rename case when column
2.8.10.Returning Multiple Columns
2.8.11.Table renaming in from clause
2.8.12.Use table name to reference column name