Using DAO Data Access Objects Code. This tutorial describes how you can use DAO code directly within your VB6 application instead of being tied to a Visual Basic control. Fu5lwO2k4XE/hqdefault.jpg' alt='Rename File In Vb6.0' title='Rename File In Vb6.0' />Originally Written By The. VBProgramer. Why. Use Code Instead of the Data Control The advantage of using. VB code. This method works well for small, one time projects that. The disadvantage of using. Also, forms built using the data control are not always easy to debug. If. you think your project needs to be modified or maintained by other programmers. The advantage of using. VB code to produce data entry forms is that you have total control. You decide when to open the database and. This. capability can be a real advantage in multiuser file sharing settings where. Another advantage of using VB code for your data entry forms is that. When you have a fully debugged set of data entry routines, you can quickly. Because the form rely on. The primary drawback for. VB code to create data entry forms is that you have to handle all. For example, locating and updating. Opening the database. Opening the recordset. Locating the requested record. Loading the input controls from. Handling all user actions during. Writing the updated controls back. You also need a way for the. In giving up the data control, you give up its. VCR style navigation arrows. Despite this added. VB code gives you much. Even though you have to do a good bit of. This document shows you how. Access database using code alone. This tutorial explains in great depth how the SQL language works. It has many examples and uses access databases to demonstrate the SQL syntax. These Excel VBA Interview questions are being posted keeping in mind that reader is aware of working with VBA, have some programming and MS Excel background and is. PDF files that contain the Visual Studio 2005 documentation. This tutorial demonstrates a full working application using nothing but DAO code no data control this has the advantage of full control in Visual Basic. Although Visual Basic 6. UnicodeUTF16 it has several limitations Ships with ANSI only controls Label, Textbox, etc. By badbrad Date 20091120 Missed one thing. Create a zero byte file in CWindows called MSJAVA. DLL to get around the Java install. The database is named. EMPLOYEE. MDB, and is based on the sample employee file used in the tutorials. EMPLOYEE. MDB contains three. Emp. Mast, Dept. Mast, and Job. Mast. The tables are. Emp. Mast table Field Name. Data. Type. Comments. Emp. Nbr. Auto. Number. Primary Key. Uniquely. Emp. First. Text 5. Employees first name. Emp. Last. Text 5. Employees last name. Dept. Nbr. Number Long IntegerForeign Key to PK of. Dept. Mast table. Identifies which department the employee works in. Job. Nbr. Number Long IntegerForeign Key to PK of. Job. Mast table. Identifies the employees job. Hire. Date. DateTime. Date the employee was. Dept. Mast table Field Name. Data. Type. Comments. Dept. Nbr. Number Long IntegerPrimary Key uniquely. The PK index was renamed idx. Dept. Nbr. PK. in the Access interface see below. Dept. Name. Text 5. The name of the. department. A non unique index was established on this field, and the index. Dept. Name. Location. Text 5. 0The departments location. Job. Mast table Field Name. Data. Type. Comments. Job. Nbr. Auto. Number. Primary Key uniquely. The PK index was renamed idx. Job. Nbr. PK. Job. Title. Text 5. 0The job title. A non unique index was established on this field, and the. Job. Title. Min. Rate. Number SingleThe minimum hourly rate. Avg. Rate. Number SingleThe average hourly rate. Max. Rate. Number SingleThe maximum hourly rate. How to Rename Indexes in the Access UINote that in the screen shot. Dept. Mast, Dept. Nbr was set up as the primary key, and. Dept. Name this will facilitate. Dept. Name contains a particular value. Dept. Mast table in Dept. Name sequence. To examine information. Indexes icon. looks like a lightning bolt on the Access toolbar. Clicking the Indexes icon. Indexes dialog box shown below to be displayed. Note that under. the Index Name column, I renamed the indexes. The Index Name for. Dept. Nbr field was changed from Primary. Key to idx. Dept. Nbr. PK. the Access default index name for the primary key field is. Primary. Key and the Index Name for the Dept. Name field was changed. Dept. Name to idx. Dept. Name the Access default index. Field Name. The DAO. Object Model. An essential part of. Access database applications is to gain a working. DAO Data Access Objects object model, shown on the following. An object model is a representation, or conceptual map, of an objects. The objects in the object model. The objects in the object. You can think of these levels as tiers. The topmost tier in the DAO object model is the JET database. DBEngine. The second tier consists of a high level. The third, fourth and fifth tiers, etc. You traverse the tiers to find the objects you. A group of similar objects. In general, the plural. Databases, Recordsets, etc. Database, Recordset, etc. Collection Syntax. To refer to an object in a. Collection. Name. ItemKey. or Collection. Name. ItemindexItem is the default method for all collections therefore. Item can always be dropped from the above syntax, reducing it to Collection. NameKey. or Collection. NameindexAn objects key is a. For example. the Dept. Nbr field in the collection of fields of a table could be referred to. FieldsDept. Nbr. The index refers to the objects. If the Dept. Nbr field is the first field in the. Fields collection, it could be referred to as Fields0. Note It is. generally preferable to use the key rather than the index to access items in a. Since the index for an item in a collection is subject to change. In looking at the DAO object. Each of these objects. However, in a typical VBDAO application. Most likely, you will use Workspace object indirectly, the Database. Recordsets, Table. Defs, and possibly Query. Defs. collections. The collections and objects used in the sample project. Good reference material for. Access help system. In addition, there. JET DAO. One of the best books on. Microsoft Jet Database Engine Programmers Guide. Dan Haught and Jim Ferguson Microsoft Press, 1. The DAO Data Access Objects Object Model. Using. DAO in Your VB Project VB projects that will. Access style JET database must include a reference to Microsoft DAO 3. Object Library. To include this reference, go to. VB Project menu and select References. From the resulting dialog box, check that reference. Note When you use the data. VB will set it. automatically. The. Sample Project prj. DAODemoThe sample project contains. Forms frm. Main. Menu. The main menu, or. Help. The form where help files. Dept. Maint. Used to add, change, or delete. Dept. Mast tablefrm. Job. Maint. Used to add, change, or. Job. Mast tablefrm. Emp. Maint. Used to add, change, or. Emp. Mast tablefrm. Report. Menu. Allows the user to select. Style Works 2000 Universal Com Serial Port more. Crystal report to be printed. Modules Standard module containing. Common. We will look at each form in. In the general. declarations section, you see the statement. Public gobj. Emp. DB As DatabaseDatabase is a. Once the Microsoft DAO 3. Download Install Configure Bandwidthd. Object. Library has been included in your project, variables defined as any of the. DAO object model Database, Table. Def, Recordset. Field, etc. In addition to the. Center. Form routine and the Get. App. Path function, there are two database related. In this project, each. Open. Emp. Database sub when the form is. Close. Emp. Database sub when the form is unloaded. The Open. Database Method. The Sub Open. Emp. Database. contains the single statement Set gobj. Emp. DB. Open. DatabaseGet. App. Path EMPLOYEE. MDBRecall that gobj. Emp. DB was. declared as a Database variable, which is a specific type of object. Unlike standard VB variables such as Integer and String. Set statement. The Set statement establishes a valid reference to an object variable. Open. Database is a method of the Workspace object. Workspaces collection and of course Workspaces is a collection of the. DBEngine object. A Workspace object exists for each active session of the Jet. A session delineates a sequence of operations.
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