Using the Data Access Controls: DAO & ADO

Transcription

1 Using the Data Access Controls: DAO & ADO

2 VB & Database Systems New Technologies in VB6 ActiveX Data Objects (ADO) DataList and DataCombo replace DBList and DBCombo. The DataGrid is the successor to DBGrid. The Chart control is now data bound. New Hierarchical FlexGrid The Data Report is a new ActiveX designer Data Formatting and Data Validation DHTML and Data Access

3 DAO Control Previous versions of VB used the Data Access Object Control: DAO. DAO is/was particularly good for MS- Access and MS-SQL-Server databases. DAO has limitations in dealing with non- Microsoft databases.

4 DAO Connections VB- Program DAO Control MS Jet Engine MS-Access Database SQLPassThrough-Mode ODBC ORACLE

5 Terminology RECORDSET Represents the data in a table, or the result of a SQL select statement. You can use recordsets to view, update, or delete data in the base tables.

6 Using the Old DAO Control Data Aware Text Boxes Data Aware OLE Container DAO Data Access Control MOVE: First, Last, Next, Previous

7 Making the DAO Application Make the following form Control Names: txtfirstname txtlastname txtid lblid olephoto datemployee

8 datemployee: DAO Change the following attributes of datemployee Name: datemployee DatabaseName:Nwind.mdb RecordSource: Employees Caption: Employees

9 Data Aware Controls Change the Text-boxes and OLE box to: C o n t r o l N a m e D a t a S o u r c e D a t a F ie ld T e x t1 tx tl a s tn a m e d a te m p lo y e e L a s tn a m e T e x t2 tx tf ir s tn a m e d a te m p lo y e e F ir s tn a m e T e x t3 tx ti D d a te m p lo y e e E m p lo y e e I D O L E 1 o le P h o to d a te m p lo y e e P h o to S iz e M o d e 1 - S tre c h

10 The New ADO Control VB6 recommends using the ADO control instead of the older DAO-RDO. ADO works well with local desktop DBMS software and remote database servers. You need the Professional/Enterprise edition of VB.

11 ADO Control & OLE DB

12 Example1. ADO + JetEngine Use the ADO control to show records in the MS-Access BIBLIO.MDB database. Use the native Jet-Engine connection. Data Aware Text Boxes ADO Control

13 Example1. ADO + JetEngine Objects and Property Settings for the Authors Project. O b je c t P r o p e r t y S e t t in g F o rm C a p tio n A u th o rs : A D O & Je te n g in e A D O D C 1 N a m e C a p tio n a d o A u th o r A u th o rs T e x t1 N a m e D a ta S o u r c e D a ta F ie ld tx ti D a d o A u th o r A u _ I D T e x t2 T e x t3 N a m e D a ta S o u r c e D a ta F ie ld N a m e D a ta S o u r c e D a ta F ie ld tx tn a m e a d o A u th o r A u th o r tx ty e a r B o r n a d o A u th o r Y e a rb o rn

14 Example1. ADO + JetEngine ConnectionString The ConnectionString can be set up at design and run time. It tells VB how to get to the database. The Options are: Jet Engine OLE DB (native to Microsoft Access) ODBC (generic)

15 Example1. ConnectionString Adjust the property page of adoauthor Set CommadType: 2-adCmdTable Click on ConnectionString button

16 Example1. Use Connection String Click on Option3 Push BUILD

17 Example1. Jet 3.51 Provider Pick: JET 3.51 OLE DB Provider Click on Next

18 Example1. Database Name Click on button to locate file Select Biblio.mdb Test the connection, then push OK.

19 Example1. RecordSource Push on the adoauthor RecordSource attribute Choose the Authors table Apply, then OK

20 Example1. Save & Run Save all your files. Execute the application.

21 Example2. Using ODBC Open Data Base Connectivity (ODBC) is a software protocol to allow client applications -written in any language- to gain access to a database system.

22 Example2. ODBC Making ODBC connections in VB is a convenient practice because the steps involved are the same for all types of compliant database systems. VB Program ADO ODBC Databases MS-Access MS-SQL Server Oracle Sybase IBM - DB2 SAP...

23 Example2. ODBC Data Source Odbc Data Source A named Open Database Connectivity (ODBC) resource that specifies the location, driver type, and other parameters needed by an ODBC driver to access a database.

24 Example2. Adding an ODBC Data Source Bring the ODBC-Administrator from the Control Panel Choose the 32bit ODBC manager

25 Example2. Adding an ODBC Data Source Click on the Add button Select driver

26 Example2 1- Name the source: mybibliolink 2- Add a comment 4- Locate the file 5- Push OK 3- Click Select