Oracle SQL Developer

Retrieving Data With Queries■■■■Format, perform calculations on, store, and print from query resultsExamine table and object definitionsDevelop and run batch scriptsPerform database administration6.1.2 Types of SQL StatementsAll operations performed on the information in an Oracle database are run using SQLstatements. A statement consists partially of SQL reserved words, which have specialmeaning in SQL and cannot be used for any other purpose. For example, SELECT andUPDATE are reserved words and cannot be used as table names.A SQL statement is an instruction. The statement must be the equivalent of a completeSQL sentence, as in:SELECT last_name, department_id FROM employees;Oracle SQL statements are divided into several categories:■ Data Manipulation Language (DML) StatementsThese statements query, insert, update, delete data in tables.■ Transaction Control StatementsThese statements commit or rollback the processing of transactions. A group ofchanges that you make is referred to as a transaction.■Data Definition Language (DDL) StatementsThese create, alter, and drop database objects.6.2 Retrieving Data With QueriesYou can retrieve data from rows stored one or more database tables or views with aquery using the SQL SELECT statement. The SELECT statement retrieves the all of orpart of the column data from rows depending on the conditions that you specify inWHERE clauses. The group of columns that are selected from a table is referred to as theSELECT list.■■■■■■Displaying Data Using the SELECT StatementUsing Character Literals in SQL StatementsUsing a Column Alias to Change Headings When Selecting DataRestricting Data Using the WHERE ClauseSorting Data Using the ORDER BY ClauseDisplaying Data From Multiple Tables6.2.1 Displaying Data Using the SELECT StatementWith the SQL SELECT statement, you can query and display data of tables in adatabase.Example 6–1 shows how to use SELECT to retrieve data from the employees table. Inthis example, the data for all columns in a row (record) of the employees table isretrieved with the use of the wildcard (*) notation. Note the use of comments to6-2 SQL Developer Online Help