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Access

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  • 1. Access Introduction to AccessDatabase any collection of informationTable the heart of a database. It is composed of fields and records.Record contains information about a particular thing.Field contains information relating to a specific item.Cell where a record and a field intersectForm a document with blank spaces for entering informationReport a document that gives an account of a certain subjectQuery the process of weeding out unnecessary information, so only the information needed is seen more clearlyEven though tables, reports, forms, and queries may be created in separatesteps, they are all related. • Tables are the central focus of all activities • Reports summarize and organize the table data • Forms help enter information into the table • Queries help find information needed that is in the tableWizard a series of dialog boxes that guide the user through the process of accomplishing a task. It is a mini program that “interviews” the user – asking questions about what the user wants to accomplish. The answers to the questions posed by the wizard are then used to create whatever is needed according to the user’s specificationsWhat is a database?What is a table?What is a record?What is a field?To get a better understanding on what a database is all about, let us think of it asa filing cabinet with drawers.Each drawer has folders and papers.The papers contain pieces of information about a student. Each piece ofinformation is what is known as a FIELD.Papers about a particular student are stored in a folder labeled with thestudent’s name and ID number. Each folder is what is known as a RECORD.Each folder is placed in a drawer of the filing cabinet. The drawer is labeled bythe class section. The drawer that contains the folders is what we can refer to asa TABLE.
  • 2. Each drawer is in a filing cabinet. Each drawer has the label of a class section(106B, 106G, 106I). Because they all refer to particular sections and they are allrelated to students’ records, they are stored in the same filing cabinet. The filingcabinet that contains all these information is what we can call a DATABASE.Let us now review what we have learned about a database from the smallestentity to the largest.Individual characters make up a FIELD which is a single piece of information.A collection of fields are stored in a RECORD.A collection of records are contained in a TABLE.A group of tables are stored in a DATABASE.FORMS A form is an electronic version of a paper form. It is used to enterinformation, edit information, and to view the information on the screen. A form has two parts: Labels - show the field names Text box - where information corresponding to the label is entered.Field Properties, Input Mask, Keys and Indexes, Modifying a TableProperties determine how a field is entered, displayed and stored. The propertiesshown in the window depend on the type of field. Some properties will havedefault values, others will be blank. Properties give you greater control over yourdatabase and they ensure your information is valid.Properties used by Access: 1. Field Size: for text and number fields. 2. Byte: can only accept a number from 0 to 255. 3. Integer and Long Integer: numbers without decimal places. Integer can be between negative and positive 32,768; Long Integer can be between negative and positive 2 billion. 4. Single and Double: numbers with decimal places. Single can contain up to 38 places; Double can contain up to 308 places. 5. Replication ID: used for primary key fields with tables in briefcases. 6. Format: determines how information appears on screen and when printed. With text fields > converts all lowercase to uppercase characters. 7. Decimal places: number of decimal places for number and currency fields. 8. New Values: for AutoNumber fields, select either increment or random. 9. Input Mask: specifies the format in which information is entered.
  • 3. 10. Caption: a more descriptive name for the field to be used in forms and reports. Use a caption when you enter a short field name to fit in a datasheet column and to conform to other database naming conventions. 11. Default Value: information that will appear in the field automatically, but that you can change in the datasheet or form. 12. Validation Rule: a logical expression that determines whether Access will accept your field entry. 13. Validation Text: a message that appears if information violates the validation rule. 14. Required: determines if an entry must be made in the field. 15. Allow Zero Length: allows a string with nothing in it. 16. Indexed: determines if an indes will be creaetd to provide faster searches.Input MaskPlain and simply, input masks do two important things: 1. They save you the trouble of entering certain characters. 2. They ensure that even the most careless person can’t screw up your database.When you want to ensure that data gets entered in the correct format, use aninput mask. The following are the Mask Characters and the Allowable Entries Allowable Entry(ies)Mask Character 0 Only digits 0 to 9, required 9 Optional digit or space # Digit/space, as well as + and - L Letter A to Z, required ? Optional letter A to Z A Any letter or digit, required A Any optional letter/digit & Any character/space, required C Any optional character/space . Decimal point , Thousands separator :;/ Data and time separators < Convert to lowercase > Convert to uppercase Characters appear from right to left; ! this only works when characters on the left are optional
  • 4. Displays the next character; even if it is an input mask character Displays an asterisk for each character “Password” typed.The above are the mask characters. Any other character is a literal.Examples:(999)000-0000 in a telephone field displays the parentheses and hyphen in the mask.XY00000 in the inventory will display XY on the screen and the user must enter five (5) numbers.Validating Field DataInput masks help, but your table can still fall victim to the loose cannon in theoffice. Your next line of defense is the validation rule. 1. Set the Field Size. 2. Enter > in the Format property. 3. Set the default value. 4. Enter a validation rule. 5. Enter a validation text. 6. Set the Required property to Yes.Keys and IndexesPrimary Key maintains the order of the recordsIndex helps speed up searches and other operations.To Set the Primary Key 1. Click on the field to be used for the key. 2. Click on the Primary Key button (the one with the key)
  • 5. Starting Microsoft Access1A. Two Ways 1. Double click on the Microsoft Access icon on the desktop. 2. Click on Start --> Programs --> Microsoft AccessB. Select Blank Access Database. Then Click OK.C. Specify a name and location for the database and click Create.D. There are three ways of creating a Table 1. Creating Table in Design View 2. Creating Table by using wizard 3. Creating Table by entering dataE. Double Click Creating Table in Design View.F. Define each of the fields in your table. Refer to the Table Structure……. (..will be given to you on the board.) o Under the Field Name column, enter the categories of your table. o Under Data Type column, enter the type you want for you categories.  The attribute of a variable or field that determines what kind of data it can hold. For example, in a Microsoft Access database, the Text and Memo field data types allow the field to store either text or numbers, but the Number data type will allow the field to store numbers only. Number data type fields store numerical data that will be used in mathematical calculations. Use the Currency data type to display or calculate currency values. Other data types are Date/Time, Yes/No, Auto Number, and OLE object (Picture). o Under the Description column, enter the text that describes what you field is. (This field is optional). o Field Property may be filled up later.G. Before closing the Window, specify first the Primary Key. 1. Click on the Key Field. Ex. IdNum 2. Right Click and select Primary Key1
  • 6. A primary key is a field, or a collection of fields, whose values uniquelyidentify each record in a table. When you include the primary key from one table as a field in a second table to form a relationship between two tables, it is called foreign key in the second table .G. Once finished, close the Window.H. . Save the Table by encoding the TABLE NAME then Click OK. About DatabaseDataBase Management System (DBMS): <==>a collection of interrelated dataand the programs to access that data.DataBase: <==>A database is comprised of those (1) tables, (2) programs, (3)forms, (4) labels, and (5) queries related to the specific application.
  • 7. DatabaseTable: <==> a collection of information pertaining to some type ofentity. A database table might represent an entity such as clients (contactmanager) , an entity such as parts (inventory management system), an entitysuch as homes (real-estate management system), an entity such as students(grade book program), etc.Record: <==> the information related to one entity (one part, one client, or onestudent). In a client database table, each record would contain the informationrelated to one client. In a student database table, each record would containthe information related to one student.Field: <==> the individual sub-components of one record. Each database table ispartitioned into one or more fields. The fields within a client database table mightbe Name, Address, City, State, Zip, Phone, Male, Notes, etc. The fields within aHhomes database table might be Owner, Address, City, State, Zip, Phone,NoBedrooms, NoBath, Pool, Info, etc.Field Name: <==> Associated with each field must be a Field Name. The FieldName is a program variable associated with this field; this name should bemeaningful and a single token (no blanks!). It is best to use upper & lower caseletters to make this field more readable; FirstName is preferred to any of thefollowing: firstname, first_name, firstName, or First Name. The first character ofeach important word in the field name should be capitalized; there should be noblanks in the field name.Field Data Type: <==> Associated with each field must be a Data Type, alsospelled Datatype. The Data Type is absolutely essential. It is the data type thathelps to prepare the right type of container in which the user can include thedesired information. Without going into detail, it is sufficient to say that computersstore character data differently than whole numbers differently than fractionalnumbers etc. Our primary data types shall include text/char, logical/yes-no,date, numeric, and memo.Text Data Type: <==> the Text Data Type, often called the Character Data Type,prepares a container into which the user may enter any of the ASCII charactersfrom the keyboard. The field Data Type must be Text when there is characterdata such as A, B, C, ..., Y, Z, a, b, c, ... , y, z, +, -, $, %, >, (, {,etc. The text field isconfined to some fixed number of bytes/characters (size).Yes/No Data Type: <==> the Yes/No Data Type, often called the Logical DataType, prepares a container for a Yes/No or True/False type of response. Somedatabase languages allow you to do this with a Check Box, some with T/F and Y/N, and some with both.Date Data Type: <==> the Date Data Type prepares a container for dates in theformat 12/25/99 or 12-25-99. Sometimes additional formats, such as 25-Dec-99are acceptable.
  • 8. Numeric Data Type: <==> the Numeric Data Type prepares a container fornumeric information. Numeric data is often stored in the computers nativebinary format. The computer stores integer { 0, +/- 1, +/- 2, +/- 3, +/- 4, ...}differently than it stores rational {a/b | a is an integer, b is an integer, and b <> 0}numbers. We sometimes call the rational numbers fractions. Larger numbers andprecision often require more bytes for storage. It is the database designersresponsibility to select a container that is sufficiently large enough to hold all ofthe values that might be stored in the field without making the field too large; thissize can be changed later.Numeric [Byte] Data Type: <==> can be used to store numbers 0 <==> 255. [1byte]Numeric [Integer] Data Type: <==> can be used to store numbers -32,768 <==>32,767. [2 bytes]Numeric [Long Integer] Data Type: <==> can be used to store numbers-2,147,483,648<==> 2,147,483,647. [4 bytes]Numeric [Single] Data Type: <==> real/fractions represented with scientificnotation with at least 6 digits of accuracy. [4 bytes]Numeric [Double] Data Type: <==> real/fractions represented with scientificnotation with at least 12 digits of accuracy. [8 bytes] Memo Data Type: <==> the memo field is an unbound, unlimited container fortext data. It is generally stored in a file separate from the associated databasetable.Database Form: <==> a screen window into some portion of the databaseinformation. A form can contain information from database fields as well asbuttons, tabs, & controls which assist in user processing.Database Report: <==> a print formatted copy of some portion of the databaseinformation.Database Label: <==> a print copy of some portion of the database informationthat is designed especially for output on business type labels.Database Query: <==> a specialized request for some portion of the databaseinformation.Primary Goal of a DBMS: Provide a convenient and efficient environment inwhich store and retrieve information.

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