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What Are the General Rules on Data Consistency
What Are the General Rules on Data Consistency? - Oracle DBA FAQ - Understanding SQL Transaction Management All SQL statements always work with a snapshot of the database to provide data consistency. For READ WRITE transactions, the snapshot is taken when each statement starts. For READ ONLY transac...
2007-04-17, 5277👍, 0💬

What Are the System Predefined User Roles
What Are the System Predefined User Roles? - Oracle DBA FAQ - Managing Oracle User Accounts, Schema and Privileges Oracle 10g XE comes with 3 predefined roles: CONNECT - Enables a user to connect to the database. Grant this role to any user or application that needs database access. RESOURCE - Enabl...
2007-05-02, 5273👍, 0💬

How To Convert Times to Characters
How To Convert Times to Characters? - Oracle DBA FAQ - Understanding SQL Basics You can convert dates to characters using the TO_CHAR() function as shown in the following examples: SELECT TO_CHAR(SYSDATE, 'HH:MI:SS') FROM DUAL; 04:49:49 SELECT TO_CHAR(SYSDATE, 'HH24:MI:SS.FF') FROM DUAL; -- Error: S...
2007-04-23, 5273👍, 0💬

How To Load Data from External Tables to Regular Tables
How To Load Data from External Tables to Regular Tables? - Oracle DBA FAQ - Loading and Exporting Data Once you have your data entered in a text file, and an external table defined to this text file, you can easily load data from this text file to a regular table. The following tutorial exercise sho...
2007-05-01, 5272👍, 0💬

How To Get a List of All Background Sessions in the Database
How To Get a List of All Background Sessions in the Database? - Oracle DBA FAQ - Introduction to Oracle SQL Developer If you don't like to use a SELECT statement to get a list of all background sessions in the current database, you can use the Reports view to do this as shown in the following tutori...
2007-04-27, 5268👍, 0💬

How To Assign Values to Data Fields in RECORD Variables
How To Assign Values to Data Fields in RECORD Variables? - Oracle DBA FAQ - Working with Database Objects in PL/SQL If a variable is a RECORD variable, you can assign values to its data fields by using fields names prefixed with variable name as "variable.field_name". Here is a sample script assigni...
2007-04-27, 5266👍, 0💬

How To Sort the Query Output
How To Sort the Query Output? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements 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> SELEC...
2007-04-20, 5266👍, 0💬

What Happens If You Use a Wrong Connect Identifier
What Happens If You Use a Wrong Connect Identifier? - Oracle DBA FAQ - Introduction to Command-Line SQL*Plus Client Tool Of course, you will get an error, if you use a wrong connect identifier. Here is an example of how SQL*Plus react to a wrong connect identifier: SQL> CONNECT fyi/retneciyf@WRONG; ...
2007-04-28, 5262👍, 0💬

What Are the Restrictions in a READ ONLY Transaction
What Are the Restrictions in a READ ONLY Transaction? - Oracle DBA FAQ - Understanding SQL Transaction Management There are lots of restrictions in a READ ONLY transaction: You can not switch to READ WRITE mode. You can not run any INSERT, UPDATE, DELETE statements. You can run SELECT query statemen...
2007-04-17, 5261👍, 0💬

What Is Oracle
What Is Oracle? - Oracle DBA FAQ - Oracle Basic Concepts Oracle is a company. Oracle is also a database server, which manages data in a very structured way. It allows users to store and retrieve related data in a multiuser environment so that many users can concurrently access the same data. All thi...
2007-04-21, 5260👍, 0💬

Can the Query Output Be Sorted by Multiple Columns
Can the Query Output Be Sorted by Multiple Columns? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements 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> SELEC...
2007-04-20, 5260👍, 0💬

How To Join Two Tables in a Single Query
How To Join Two Tables in a Single Query? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements Two tables can be joined together in a query in 4 ways: Inner Join: Returns only rows from both tables that satisfy the join condition. Left Outer Join: Returns rows from both tables that satisfy t...
2007-04-20, 5260👍, 0💬

How To Create an Initialization Parameter File
How To Create an Initialization Parameter File? - Oracle DBA FAQ - Creating New Database Instance Manually This is Step 3. To run an Oracle database as an Oracle instance, you need to create an initialization parameter file, which contains a set of initialization parameters. The easiest way to creat...
2007-04-22, 5259👍, 0💬

What Are DDL Statements
What Are DDL Statements? - Oracle DBA FAQ - Understanding SQL DDL Statements DDL (Data Definition Language) statements are statements to create and manage data objects in the database. The are 3 primary DDL statements: CREATE - Creating a new database object. ALTER - Altering the definition of an ex...
2007-04-22, 5257👍, 0💬

What Is a SQL*Loader Control File
What Is a SQL*Loader Control File? - Oracle DBA FAQ - Loading and Exporting Data A SQL*Loader control file a text that defines how data files should be loaded into the database. It allows you to specify: Where is the input data file. The format of the input date file. The target table where the data...
2007-04-30, 5256👍, 0💬

How To Write a Query with a Left Outer Join
How To Write a Query with a Left Outer Join? - Oracle DBA FAQ - Understanding SQL SELECT Query Statements If you want to query from two tables with a left outer join, you can use the LEFT OUTER JOIN ... ON clause in the FROM clause. The following query returns output with a left outer join from two ...
2007-04-19, 5255👍, 0💬

How To Export Your Own Schema
How To Export Your Own Schema? - Oracle DBA FAQ - Loading and Exporting Data If you have a non-system user account and you want to export all data objects in the schema associated with your account, you can use the "expdp" command with the SCHEMAS parameter. Running "expdp" command with a non-system...
2007-05-01, 5248👍, 0💬

Where Is the Export Dump File Located
Where Is the Export Dump File Located? - Oracle DBA FAQ - Loading and Exporting Data If you are not specifying the dump directory and file name, the dump file will be stored in the default dump directory with the default file name. The tutorial exercise below tells you find what is your default dump...
2007-05-01, 5245👍, 0💬

What is System Global Area (SGA)
What is System Global Area (SGA)? - Oracle DBA FAQ - Oracle Basic Concepts The System Global Area (SGA) is a memory area that contains data shared between all database users such as buffer cache and a shared pool of SQL statements. The SGA is allocated in memory when an Oracle database instance is s...
2007-04-21, 5243👍, 0💬

How To Create a New Table by Selecting Rows from Another Table
How To Create a New Table by Selecting Rows from Another Table? - Oracle DBA FAQ - Managing Oracle Database Tables Let's say you have a table with many data rows, now you want to create a backup copy of this table of all rows or a subset of them, you can use the CREATE TABLE...AS SELECT statement to...
2007-05-03, 5240👍, 0💬

How To Execute a Stored Procedure
How To Execute a Stored Procedure? - Oracle DBA FAQ - Creating Your Own PL/SQL Procedures and Functions If you want to execute a stored procedure, you can use the EXECUTE statement. The example script below shows how to executes a stored procedure: SQL> set serveroutput on; SQL> CREATE PROCEDURE Gre...
2007-04-26, 5238👍, 0💬

How To Define an External Table with a Text File
How To Define an External Table with a Text File? - Oracle DBA FAQ - Loading and Exporting Data You can use the CREATE TABLE statement to create external tables. But you need to use ORGANIZATION EXTERNAL clause to specify the external file location and the data access driver. The tutorial exercise b...
2007-04-30, 5237👍, 0💬

How To Create a Table Interactively
How To Create a Table Interactively? - Oracle DBA FAQ - Introduction to Oracle SQL Developer If you don't want to use SQL statements to create a new table, you use SQL Developer to create one interactively. Follow the steps below to create a new table called: TIP Right-click on the Tables in the obj...
2007-04-27, 5237👍, 0💬

How To Set a Transaction To Be READ ONLY
How To Set a Transaction To Be READ ONLY? - Oracle DBA FAQ - Understanding SQL Transaction Management If you want a transaction to be set as READ ONLY, you need to the transaction with the SET TRANSACTION READ ONLY statement. Note that a DML statement will start the transaction automatically. So you...
2007-04-17, 5237👍, 0💬

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