java barcode reader free download The order of the SELECT command components as displayed in Table 2-1 is also a good order to Tip in Font

Drawer ECC200 in Font The order of the SELECT command components as displayed in Table 2-1 is also a good order to Tip

The order of the SELECT command components as displayed in Table 2-1 is also a good order to Tip
DataMatrix Generation In None
Using Barcode generator for Font Control to generate, create Data Matrix image in Font applications.
www.OnBarcode.com
Encode Data Matrix In None
Using Barcode drawer for Font Control to generate, create Data Matrix 2d barcode image in Font applications.
www.OnBarcode.com
think about them when writing SQL statements. Notice that the SELECT clause is almost the last one.
Code 39 Creation In None
Using Barcode encoder for Font Control to generate, create Code 39 Extended image in Font applications.
www.OnBarcode.com
Paint UPC-A Supplement 5 In None
Using Barcode encoder for Font Control to generate, create UPC-A Supplement 2 image in Font applications.
www.OnBarcode.com
Components of the SELECT command implement three of the relational operators introduced in 1 (Section 1.6) as follows:
UPC - 13 Drawer In None
Using Barcode creator for Font Control to generate, create UPC - 13 image in Font applications.
www.OnBarcode.com
Encoding Barcode In None
Using Barcode creation for Font Control to generate, create Barcode image in Font applications.
www.OnBarcode.com
CHAPTER 2 INTRODUCTION TO SQL, i SQL*PLUS, AND SQL*PLUS
Print EAN / UCC - 13 In None
Using Barcode drawer for Font Control to generate, create EAN / UCC - 14 image in Font applications.
www.OnBarcode.com
EAN-8 Generator In None
Using Barcode maker for Font Control to generate, create European Article Number 8 image in Font applications.
www.OnBarcode.com
The SELECT component acts as the projection operator. The FROM component implements the join operator. The restriction operator corresponds to the WHERE component. Now that we are on the subject of relational operators, note that the union, intersection, and difference (minus) operators are also implemented in SQL. You can use these three set operators to combine the results of multiple SELECT commands into a single result table, as illustrated in Figure 2-2. We will revisit these operators in 8.
Recognizing Data Matrix 2d Barcode In None
Using Barcode scanner for Software Control to read, scan read, scan image in Software applications.
www.OnBarcode.com
Create Data Matrix In None
Using Barcode generator for Excel Control to generate, create Data Matrix image in Office Excel applications.
www.OnBarcode.com
Figure 2-2. SQL set operators syntax diagram
Make Barcode In None
Using Barcode creation for Software Control to generate, create Barcode image in Software applications.
www.OnBarcode.com
Recognizing UCC - 12 In Visual Basic .NET
Using Barcode recognizer for Visual Studio .NET Control to read, scan read, scan image in .NET applications.
www.OnBarcode.com
Security
USS-128 Drawer In Objective-C
Using Barcode encoder for iPad Control to generate, create USS-128 image in iPad applications.
www.OnBarcode.com
Generating UPC-A Supplement 5 In None
Using Barcode drawer for Software Control to generate, create UPC-A image in Software applications.
www.OnBarcode.com
SQL offers several commands to implement data security and to restrict data access. First of all, access to the database must be defined. User authorization is implemented by providing database users a login name and a password, together with some database-wide privileges. These are the most important commands in this area: CREATE USER, to define new database users ALTER USER, to change properties (privileges and passwords) of existing database users DROP USER, to remove user definitions from the database
Data Matrix 2d Barcode Generation In Java
Using Barcode generation for Eclipse BIRT Control to generate, create DataMatrix image in Eclipse BIRT applications.
www.OnBarcode.com
Generating GS1 - 13 In Visual Studio .NET
Using Barcode maker for Reporting Service Control to generate, create European Article Number 13 image in Reporting Service applications.
www.OnBarcode.com
Privileges and Roles
Barcode Generator In None
Using Barcode maker for Office Word Control to generate, create Barcode image in Word applications.
www.OnBarcode.com
UCC - 12 Generator In .NET Framework
Using Barcode generator for ASP.NET Control to generate, create UPC-A Supplement 5 image in ASP.NET applications.
www.OnBarcode.com
If users are authorized to access the database, you can implement fine-grained data access by granting specific privileges. The Oracle DBMS offers two types of privileges: system privileges and object privileges. System privileges pertain to the right to perform certain (nonobject-related) actions; for example, you can have the CREATE SESSION privilege (allows you to log on to the database) and the CREATE TABLE privilege. Oracle supports approximately 140 different system privileges. Object privileges involve the right to access a specific database object in a specific way; for example, the right to issue SELECT, INSERT, and UPDATE commands against the EMPLOYEES table. Table 2-2 lists the most important Oracle object privileges.
Encoding Barcode In Java
Using Barcode encoder for Java Control to generate, create Barcode image in Java applications.
www.OnBarcode.com
EAN-13 Supplement 5 Drawer In .NET
Using Barcode generation for VS .NET Control to generate, create UPC - 13 image in VS .NET applications.
www.OnBarcode.com
CHAPTER 2 INTRODUCTION TO SQL, i SQL*PLUS, AND SQL*PLUS
Note Granting and revoking system privileges is typically a task for database administrators. See
Oracle SQL Reference for more details on both system and object privileges.
Table 2-2. Important Oracle Object Privileges
Object Privilege
ALTER DELETE EXECUTE FLASHBACK INDEX INSERT REFERENCES SELECT UPDATE
Allowable Action
Change the table structure (with ALTER TABLE) Delete rows Execute stored functions or procedures Go back in time (with FLASHBACK TABLE) Create indexes on the table Insert new rows Create foreign key constraints to the table Query the table (or view) Change column values of existing rows
The Oracle DBMS allows you to group privileges in roles. Roles make user management much easier, more flexible, and also more manageable. The following are the corresponding SQL commands used to administer these privileges and roles: GRANT, to grant certain privileges or roles to users or roles REVOKE, to revoke certain privileges or roles from users or roles A typical scenario is the following: CREATE ROLE <role name> GRANT privileges TO <role name> GRANT <role name> TO user(s) The first step creates a new (empty) role. The second step (which can be repeated as many times as you like) populates the role with a mix of object and system privileges. The third step grants the role (and thereby all its privileges) to a user in a single step. Roles have several useful and powerful properties: Roles are dynamic; further changes to the role contents automatically affect all users previously granted that role. Roles can be enabled or disabled during a session. You can protect roles with a password. In that case, only users who know the role password can enable the role. The most important advantage of roles is their manageability.
CHAPTER 2 INTRODUCTION TO SQL, i SQL*PLUS, AND SQL*PLUS
GRANT and REVOKE
Each table has an owner, who is the user who created the table. Table owners are able to grant privileges on their tables to other database users using the GRANT command. As soon as you create a table, you implicitly get all object privileges on that table, WITH GRANT OPTION, as illustrated in Figure 2-3, which shows the syntax of the GRANT command.
Note System privileges and roles are not considered, so the syntax diagram in Figure 2-3 is incomplete.
Figure 2-3. The GRANT command syntax diagram Here are some comments about the GRANT command: Table owners cannot grant the right to remove a table (DROP TABLE) to other database users. Note, however, that Oracle supports a (rather dangerous) DROP ANY TABLE system privilege. If you want to grant all object privileges to someone else, you can use the keyword ALL (see Figure 2-3). (Instead of ALL PRIVILEGES, the Oracle DBMS also allows you to specify ALL.) With a single GRANT command, you can grant privileges to a single user, a list of users, a role, or all database users. You can address all database users with the pseudo-user PUBLIC (see Figure 2-3). The UPDATE privilege supports an optional refinement: this privilege can also be granted for specific columns, by specifying column names between parentheses. In principle, there is no difference between tables and views when granting object privileges; however, the privileges ALTER, INDEX, and REFERENCES are meaningless in the context of views. The GRANT OPTION not only grants certain object privileges, but also grants the right to the grantee to spread these privileges further.
Copyright © OnBarcode.com . All rights reserved.