C# win forms supports how many combo boxes?
the c # win forms supports three types of combo boxes they are simple combo, drop down combo and drop down list . in simple combo edit table combo is there.it always in search mode.in drop down combo edit table combo is there and search takes place if combo is enabled.in drop down list non-editable combo is there and search takes place if combo box is expanded.
Observation :- if the combo box type is drop down list in order to get the item selected by the user selected items property should be used. if the combo box type is other than drop down list then text property should be used to get the value .
To do :- Add a window form. design the form as per the requirements Properties :- label one -text- simple combo. combo box one — drop down style — simple. label two — text- drop down. label three — text — drop down list. button one -text -submit name- btnsubmit . button two — text — close name.btnclose.
Introduction to database connectivity :- The Database it is used to maintain the data perm.such that the data can be reused and managed is an Effected manner.it can be categorized in two categories.
one is ISAM Index sequential access Mode Db :- these are stand alone data bases. for example Ms-access Excel etc. second one is Virtual sequential Access Mode :- these are client server based database for :- SQL Server,Oracle etc.
Data base connectivity before .net :- In this application, application divided in to three objects one is DAO, RDO, and ADO in DAO -jet engines connecting to ISAM DB .In RDO — ODBC drivers connecting to both ISAM Data base and VSAM data base.and in ADO — OLE data base provides connecting to only VSAM data base.
Overview :- DAO Data Access Object : it is a special data model introduced to interact with ISAM database using JET Engines.Limitations :- If used to interact with VSAM data base then securing related problems will raise. RDO Remote Data Objects : it is a special data model introduced to interact with VSAM data base using ODBC open data base connectivity drivers. Limitation :- If used to interact with the ISAM data base performance related issues will be raised . ADO Activex Data Objects :- It is very power full data model.