ado net c# example

Today I reviewed the ADO and summed up their knowledge.ADO is a set of classes that expose data access services to. NET programmers. Provides access to a variety of relational data, XML, and application data.All data access classes are located in System.Data.dll. The System.Data contains a dataset and other support classes, and the System.Data.SqlClient data provider is dedicated to the SQL Server database.

In versions earlier than 2.0, a connection is usually opened and closed for each database server request, and only one command can be executed at the same time, that is, asynchronous processes are not supported, opening a connection to the database server is a resource-consuming operation. It would be nice if you can reuse the connection and support asynchronous processes... now, Mars in 2.0 and support for asynchronous processes can implement this .... The result set of multiple active result s

ADO. NET generic database category, general database ado.net The examples in this article share the ADO. NET generic database category for your reference. The details are as follows: Using System; using System. collections. generic; using System. linq; using System. text; using System. threading. tasks; using System. d

Methods and Techniques for using ADO. NET The following code illustrates how to use the SqlDataAdapter object to generate a DataSet or able command. It retrieves a group of product categories from the SQL Server Northwind database. Using System. Data; Using System. Data. SqlClient; Public DataTable RetrieveRowsWithDataTable () { Using (SqlConnection conn = new SqlConnection (connectionString )) { Conn. Open

[Transfer] http://www.bitscn.com/pdb/dotnet/200807/147205.html If youProgramThe SQL statement or stored procedure executed in only returns the computed "single value", for example: Select count (*) from employee data table Or only the "first" column value of the "first" record meeting the condition will be returned. For example: Select email from employee data table where name = 'David' We can use

In these days of self-study, now summarize some of the knowledge points in C # connected to the database:1. To connect to a database using connection:(1). Add namespace System.Data.SqlClient (Note: Beginners often forget)(2) Define the connection string. When connecting to a SQL Server database:server= server name; database= database name; uid= username; pwd= password; for example, to connect to the Student

try-- If an exception occurs, enter the catch code segment.Begin catchRollback transaction -- roll back the transactionSelect error_message () as [Message] -- output error messageEnd catch The preceding Code fails after execution. The error message is: "The unique key constraint 'uq _ users_username' is violated '. Duplicate keys cannot be inserted in the object 'dbo. users ". Note that in SQL Server, if the transaction is not explicitly declared, the system will allocate a recessive transac

We know that in ADO you can use TransactionScope to commit or cancel multiple SqlConnection (multiple database connections) of SQL statements into one thing, but use TransactionScope with extra care, because when transacti Onscope in special cases need to start MSTDC (Distributed transaction Management), then we see when TransactionScope need to start mstdc?First of all, the code in this example and the dat

Database Operations mainly involve executing commands and reading data. 1. Connection To access the database, you must first establish a connection with the database. In ADO. net, the connection object is used to establish a connection with the database. For example, the code used to establish a connection to the mycharge database on the sqlserver Server: Di

The following example shows how to call a stored procedure in ADO. net. I chose only one method. To tell the truth, I don't like a variety of methods to handle problems. This divergent approach does not seem necessary in programming. Select your preferred method. Here, SQL server has a sample database northwind. Take the region table in northwind as an

=192.168.121.130) (port=1521)) (CONNECT_DATA= (SERVICE_NAME=ORCL))); Persist Security info=true; User Id=scott; Password=tiger; ";where Oracle database server ip:192.168.121.130Servicename:orclUser name: ScottPassword: Tiger4. View the instance name of Oracle, log in with SYS as DBA, execute the statement select name from V$database;5,c# CodeUsing system;using system.collections.generic;using system.configuration;using Oracle.ManagedDataAccess.Client;

ado| data In the development based. NET Platform database application, we generally use dataset, as the core class of Ado.net it provides us with powerful functions, and the whole looks like a small database in memory, including the DataTable, DataView, DataRow, DataColumn, constraint and DataRelation. I was a little excited when I saw it. Here are some examples of some of my experiences to illustrate the o

errors in SQL execution1. Critical XXX not supported2. There is a grammatical error near xxxThe SQL statement is wrong3. Invalid column name xxxThe SQL statement is wrong4. command requires an already opened connectionConnection not openViii. Example: Administrator login (based on account number and password, query people)public int Adminlogin (string username, string password){int count =-1;SQL statementsString sql = "Select COUNT (1) from Admin WHE

Using ADO. Net with parameterized stored procedures ADO. net class that deals with input and output stored procedure parameters is dbcommand. this shouldn't come as a big surprise-dbcommand is responsible for executing commands on the database, so it makes sense that it shoshould also deal with their parameters. (

From http://www.codeproject.com/KB/grid/ExcelAdapter.aspx On the recent project I worked on, I had a requirement to load data from an Excel spreadsheet to a database on a regular basis. my goal was to load the data from Excel to a ADO. net dataset and run my business rules. I couldn't find any articles addressing this problem and so I decided to write one. There are two projects added in the source code

Tags: string existence blog Results stitching is the parameter representation selectUsing string concatenation to stitch the SQL statement required parameters into the SQL statement to be executed (parameters are generally only SQL statement filter), the user's malicious input may result in a different query resultsExample: A login example (username and password are the user's input username and password)."SELECT COUNT (*) from t_users where Username=

ADO. NET1.vb.net:Vb.net does not support database operations. NET Framwork SDK for database programming class libraries and Microsoft MDAC implementation, where ADO. NET is. NET Framwork SDK is an important part. It is a general term for class libraries used to operate Numer

Today, when studying other technologies, I checked the latest implementations of SQLite in. net. We found such a good thing. The home page is translated as follows: System. Data. SQLiteIs an originalSQLiteEnhanced version.It will be an original versionSqlite3.dllCompletely alternative(You can even rename itSqlite3.dll ).It does not need to be linked. NetRun, so it can be detached from. NetIndependent release,However, it is embedded with a completeAd

Previous http://www.bkjia.com/kf/201112/112880.html DataSet class The DataSet object can be regarded as a Cache, which can keep the data queried from the database and even display the whole database. DataSet can not only store multiple tables, but also obtain data Table structures such as primary keys through the DataAdapter object and record the association between data tables. The DataSet object can be called ADO.

When you generate an ADO. NET Entity Data Model (Entity Data Model) through a database, the number of entity classes generated may be less than the number of data tables. The following describes two possible causes. 1. All columns of the data table can be empty. When a data table has a primary key, the object data model uses the primary key as the entity key to identify an object. If the data table does n