Remove function keys from screen. Restrict record addition, deletion, or updates. Protect individual fields from update. System Requirements. Contact us! These are the journals for the database; the redo logs record all changes to the user objects or system objects.
If any type of failure occurs, the changes recorded in the redo logs can be used to bring the database to a consistent state without losing any committed transactions. In the case of non-data loss failure, Oracle can apply the information in the redo logs automatically without intervention from the DBA. The redo log files are fixed in size and never grow dynamically from the size at which they were created.
Once assigned when the row is first inserted into the database , it never changes until the row is deleted or the table is dropped. The ROWID consists of the following three components, the combination of which uniquely identifies the physical storage location of the row. What is Oracle Block?
Can two Oracle Blocks have the same address? The block size should be a multiple of the operating system block size. Regardless of the block size, the entire block is not available for holding data; Oracle takes up some space to manage the contents of the block. This block header has a minimum size, but it can grow.
These Oracle blocks are the smallest unit of storage. Increasing the Oracle block size can improve performance, but it should be done only when the database is first created. Each Oracle block is numbered sequentially for each database file starting at 1.
Two blocks can have the same block address if they are in different database files. What is database Trigger? The trigger can e defined to execute once for the entire statement or once for every row that is inserted, updated, or deleted. For any one table, there are twelve events for which you can define database triggers. Name two utilities that Oracle provides, which are use for backup and recovery.
These utilities are Export and Import. The Export utility dumps the definitions and data for the specified part of the database to an operating system binary file. The Import utility reads the file produced by an export, recreates the definitions of objects, and inserts the data If Export and Import are used as a means of backing up and recovering the database, all the changes made to the database cannot be recovered since the export was performed.
The best you can do is recover the database to the time when the export was last performed. What are stored-procedures? And what are the advantages of using them. Stored procedures are database objects that perform a user defined operation. A stored procedure can have a set of compound SQL statements. A stored procedure executes the SQL commands and returns the result to the client. Stored procedures are used to reduce network traffic.
Use of this mechanism enables execution to continue if the error is not severe enough to cause procedure termination. The exception handler must be defined within a subprogram specification. Errors cause the program to raise an exception with a transfer of control to the exception-handler block.
After the exception handler executes, control returns to the block in which the handler was defined. If there are no more executable statements in the block, control returns to the caller. This technique of raising the exception is used to invoke all user-defined exceptions. Table below gives a complete list of internal exceptions. In addition to this list of exceptions, there is a catch-all exception named OTHERS that traps all errors for which specific error handling has not been established.
The count and data types of formal parameters are also considered. To further ensure calling the proper procedure, you can use the dot notation.
Prefacing a procedure or function name with the package name fully qualifies any procedure or function reference. Spurious tuples may occur due to i. Bad normalization ii. Theta joins iii. A B C is a set of attributes. Thus the given FDs is in 1NF. A dominant entity is the entity a on the N side in a 1 : N relationship b on the 1 side in a 1 : N relationship c on either side in a 1 : 1 relationship d nothing to do with 1 : 1 or 1 : N relationship. What is Storage Manager? It is a program module that provides the interface between the low-level data stored in database, application programs and queries submitted to the system.
What is Buffer Manager? It is a program module, which is responsible for fetching data from disk storage into main memory and deciding what data to be cache in memory.
What is Transaction Manager? It is a program module, which ensures that database, remains in a consistent state despite system failures and concurrent transaction execution proceeds without conflicting.
What is File Manager? It is a program module, which manages the allocation of space on disk storage and data structure used to represent information stored on a disk. What is Authorization and Integrity manager? It is the program module, which tests for the satisfaction of integrity constraint and checks the authority of user to access data.
What are the four objectives of the selection of a data type? A data type should be selected so that all possible values are represented using minimal storage space. The data type should help to ensure data integrity and support all possible data manipulations i. Describe the four types of indexes. A unique primary index is unique and is used to find and store a row. A nonunique primary index is not unique and is used to find a row but also where to store a row based on its unique primary index.
A unique secondary index is unique for each row and used to find table rows. A nonunique secondary index is not unique and used to find table rows. What is denormalization and why would someone consider doing so? Denormalization is the process of taking normalized relations and changing them so that they are not longer normalized.
This process may lead to anomalies and create data redundancy as negative consequences. However, the revised relations should improve database performance. Compare a hierarchical and network database model? The hierarchical model is a top-down structure where each parent may have many children but each child can have only one parent. This model supports one-to-one and one-to-many relationships.
The network model can be much more flexible than the hierarchical model since each parent can have multiple children but each child can also have multiple parents. This model supports one-to-one, one to- many, and many-to-many relationships. Describe the differences between vertical and horizontal portioning.
Horizontal portioning is where the rows in a relation are separated by some criteria and placed into a new relation or file with the same layout as the original relation in this case only the records in each file differ. Vertical portioning is where the columns in a relation are separated by some criteria and placed into a new relation or file with a different layout as the original relation. Explain the difference between a dynamic and materialized view.
A dynamic view may be created every time that a specific view is requested by a user. A materialized view is created and or updated infrequently and it must be synchronized with its associated base table s.
Discuss some of the techniques that can be used to tune operational performance. Choosing primary and secondary keys can increase the speed of row selection, joining, and row ordering. Selecting the appropriate file organization for base tables and indexes can also improve performance. Clustering related rows together and maintaining statistics about tables and indexes can lead to increased efficiency.
Briefly describe the three types of SQL commands. Data definition language commands are used to create, alter, and drop tables. Data manipulation commands are used to insert, modify, update, and query data in the database. Data control language commands help the DBA to control the database.
What are the steps to follow when preparing to create a table? Identify the data type, length, and precision for each attribute. Identify the columns that can accept a null value. Identify the columns that need to be unique.
Identify primary and related foreign keys with the parent table being created before the child. Determine default values. Determine where the domain values are that need to be constrained. Create the indexes. What are some disadvantages of a standard language such as SQL?
A standard language can hinder the effort to create a new language. One standard is never enough to meet all of the business needs. A standard can be a compromise among interested parties which can cause the standard to not be ideal. If a standard is altered by some, than portability between. Explain a join between tables A join allows tables to be linked to other tables when a relationship between the tables exists.
Describe and contrast a trigger and a procedure. Triggers are stored and controlled in the DBMS. A procedure is also stored in a database. A procedure is not executed automatically. Briefly describe an outer join. An outer join includes the records that match and those that do not have a matching value in another table. Outer joins are not easily used with more than two tables. Describe a subquery. A subquery is a query that is composed of two queries.
In some cases the inner query provides results for the outer query to process. In other cases, the outer query results provide results for the inner query correlated subquery.
Describe the difference between embedded and dynamic SQL. These statements do not change unless the source code is modified. The statements generated do not have to be the same each time. Explain the difference between two and three-tier architectures. A three-tier architecture includes a client and two server layers.
The application code is stored on the application server and the database is stored on the database server. A two-tier architecture includes a client and one server layer. The database is stored on the database server. QBE is a direct-manipulation database language that uses a graphical approach to query construction. In order to use ODBC, a driver, server name, database name, user id, and password are required. ODBC is important for Internet applications and has gained wide acceptance.
Compare a thin and a fat client. A fat client is a PC that is responsible where most processing occurs on the client rather than the server. Some of the fat client activities include processing, presentation logic, and business rules logic. A thin client is a PC where only limited processing occurs. In these cases, more processing should occur on the application server. You can perform more complex functions and error handling can be accommodated by VBA.
VBA code will execute faster since code runs faster than macros and maintenance is easier because VBA modules are stored with the forms and reports. Reading VBA is easier because you can see the entire code. Finally, you can pass parameters and use OLE automation better.
Describe middleware applications that ease the connection of databases to Web applications. Both require the use of several files. Both use tags and are executed on the server.
Both Internet Explorer and Netscape can access these files. The programmer does not need to be concerned with the client when they work with this middleware. JavaScript shares many features with Java. Developers use it to achieve interactivity. JavaScript is an open language and does not require a license. It is supported by both Internet Explorer and Netscape. VBScript is similar to JavaScript. It is based on Visual Basic but is simpler. Microsoft developed this language.
Describe Web Services. Web Services are improving the ability of computers to communicate over the Internet. These services use XML programs and usually run in the background.
Easier integration of applications may be possible because developers do not need to be familiar with the technical details with applications that are being integrated. UDDI is a technical specification for creating a distributed registry of Web services and businesses that are open to communicating through Web services. Provide an overview of XML. XML is used to structure and manipulate data involved with a browser and is becoming the standard for e-commerce.
Describe Website security issues. Includes called program and example print program. Have your dumb buddy sit on the right side of your monitor then run this classic I Am With Stupid finger pointer. Visit the Games page for several entertaining 2 and 3D programs. It started as a simple program for testing functions as two dimensional array indexes. Got way out of hand mutating into full blown game pitting you against the power of the iSeries. The most complex game code ever written for the iSeries.
Unique hand scoring system shows card sets and point values. Robust strategy optimization routines. If you like Cribbage, you will be amazed by this one. Pyramid variation of Solitaire for the iSeries!. Addictive fun. Select all pairs of cards scoring 13 to win. I use this game when I am thinking. Rubiks gurus check out the Inductive Rules by Peter Suber. Uses a hash table and the random number API to sort a deck of cards.
Also uses the concept of implicitly defined arrays as DS subfields of defined arrays.
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