What is ExecuteQuery in C#?

What is ExecuteQuery in C#?

ExecuteQuery(Type, String, Object[]) Executes SQL queries directly on the database. ExecuteQuery(String, Object[]) Executes SQL queries directly on the database and returns objects.

What is SqlCommand in C#?

SqlCommand in C# allow the user to query and send the commands to the database. SQL command is specified by the SQL connection object. Two methods are used, ExecuteReader method for results of query and ExecuteNonQuery for insert, Update, and delete commands. It is the method that is best for the different commands.

What is difference between ExecuteNonQuery and ExecuteQuery?

ExecuteReader() returns an object that can iterate over the entire result set while only keeping one record in memory at a time. ExecuteNonQuery() does not return data at all: only the number of rows affected by an insert, update, or delete.

How do I fix the ExecuteReader Connection property has not been initialized?

That said, there are a few things you should correct in your code.

  1. Use using statements for connections. It will automatically close your connection. C# Copy Code.
  2. Also use using for readers for the same reason. C# Copy Code.
  3. Use paramterized SQL commands.

Why do we use SqlCommand?

A SqlCommand object allows you to specify what type of interaction you want to perform with a database. For example, you can do select, insert, modify, and delete commands on rows of data in a database table.

What is the difference between execute update () and executeQuery (() methods?

executeUpdate() : This method is used for execution of DML statement(INSERT, UPDATE and DELETE) which is return int value, count of the affected rows. executeQuery() : This method is used to retrieve data from database using SELECT query.

How do you handle invalid attempt to read when no data is present?

You have to call dr. Read() before attempting to read any data. That method will return false if there is nothing to read.

What difference is between ExecuteScalar () and ExecuteNonQuery ()?

Solution 1. ExecuteScalar() only returns the value from the first column of the first row of your query. ExecuteReader() returns an object that can iterate over the entire result set. ExecuteNonQuery() does not return data at all: only the number of rows affected by an insert, update, or delete.

How do I write a dynamic SQL query?

Dynamic SQL – Simple Examples

  1. DECLARE.
  2. @sql NVARCHAR(MAX),
  3. @id NVARCHAR(MAX);
  4. — run query using parameters(s)
  5. SET @id = N’2′;
  6. SET @sql = N’SELECT id, customer_name FROM customer WHERE id = ‘ + @id;
  7. PRINT @sql;
  8. EXEC sp_executesql @sql;

What is the syntax of dynamic query?

Syntax for dynamic SQL is to make it string as below : ‘SELECT statement’; To run a dynamic SQL statement, run the stored procedure sp_executesql as shown below : EXEC sp_executesql N’SELECT statement’;

How can I tell if a database connection is successful C#?

Check database connection in MySQL using C#.

  1. Step 1: Add Reference of MySql.Data.dll.
  2. Step 2: Add a class file with named MYSQL.CS.
  3. Step 3: Add the following name space. using MySql. Data. MySqlClient;
  4. Step 5: To use above function please write the below code. Create instance of class: MYSQL mysql = new MYSQL();

When we should activate the function executeQuery?

executeQuery(): This method is used to execute statements that returns tabular data (example select). It returns an object of the class ResultSet.