Running SQL Queries

Using SQL*Plus , you can execute any SQL query or statement that you desire. This includes data manipulation language (DML) statements such as INSERT, UPDATE, DELETE, MERGE, and SELECT. This also includes data definition language (DDL) statements such as CREATE TABLE, CREATE INDEX, CREATE USER, and so on. Essentially, you can execute any statement listed in the Oracle SQL Reference manual.

Example 2-1 shows a simple SELECT statement against the project table.

Example 2-1. A simple SELECT statement
SQL> SELECT * /* All columns */
  2    FROM project;

PROJECT_ID PROJECT_NAME                             PROJECT_BUDGET
---------- ---------------------------------------- --------------
      1001 Corporate Web Site                              1912000
      1002 Enterprise Resource Planning System             9999999
      1003 Accounting System Implementation                 897000
      1004 Data Warehouse Maintenance                       294000
      1005 VPN Implementation                               415000

Look again at the query shown in the example. Notice that the statement spans more than one line. Notice that it contains an embedded comment and that it ends with a semicolon. All of these things are important because they illustrate the following rules for entering SQL statements:

  • SQL statements may span multiple lines.

  • Line breaks may occur anywhere SQL allows whitespace, but blank lines are not normally allowed.

  • Comments, delimited by /*...*/, may be embedded anywhere whitespace is allowed. A comment entered this way may span multiple lines.

  • Comments denoted by a leading dash (-) may be added anywhere in a line and mark the remainder ...

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