Oracle Magazine - January/February 2012

EMPLO YEE. You can then use the following SELECT statement:

SELECT first_name, last_name, hire_date FROM employee

and drop a table name from the TABLES
node in the Connections Navigator into
the SQL Worksheet. This action automati-
cally creates an editable SELECT statement
in the SQL Worksheet whose select list
includes all the columns in the table. Figure
1 shows the result of dragging and dropping
the EMPLOYEE table into the Oracle SQL
Developer SQL Worksheet.

The SELECT list in the above statement specifies three columns—listing the first name, last name, and date of hire for every employee contained in the EMPLOYEE table, which is specified in the FROM clause. (To specify multiple columns in a SELECT list, you separate the column names with commas; a good practice is to insert a space after each comma for readability.)

When the above statement is executed, the result set is a list of all the values found in the first_name, last_name, and hire_date columns of the EMPLO YEE table, as shown in Listing 1.

Figure 1: Result of dragging and dropping the EMPLO YEE table into the SQL Worksheet

Figure 2: The SQL Worksheet icon tool bar

EVERY THING WI TH A MERE If you want to display all the columns for a particular table, you can use the asterisk (*) wildcard character as the SELECT list instead of typing the name of every column. For example

Figure 3: The Results tab in the SQL Worksheet

SELECT

FROM employee

When this statement executes, the result set displays the columns in the order in which they are defined in the table, as shown in Listing 2.

This is the same column order you see when you issue the DESCRIBE command (or when you click the Columns tab in Oracle SQL Developer), as shown in Listing 3.

You should use the asterisk wildcard character primarily for ad hoc querying— when you want an answer from the database that you have not already asked for via programmatic code. When you include SELEC T statements in programmatic blocks of code (which you’ll learn about in subsequent articles in this series), it is a good practice to list your columns of interest by name in your SELEC T lists.