What if ExecuteScalar returns null?
ExecuteScalar: If the first column of the first row in the result set is not found, a null reference (Nothing in Visual Basic) is returned. If the value in the database is null, the query returns DBNull. ExecuteScalar() is null, which is then casted to a null string and assigned to getusername .
What is the return value of ExecuteScalar?
Return Value of ExecuteNonQuery is Int32. Return Value of ExecuteScalar is System. Object. When we manipulate database data in ADO.NET code, ExecuteReader, ExecuteScalar and ExecuteNonQuery are three basic methods extensively used to run queries.
What is ExecuteScalar ()?
ExecuteScalar() in SqlCommand Object is used for get a single value from Database after its execution. It executes SQL statements or Stored Procedure and returned a scalar value on first column of first row in the Result Set.
What does ExecuteNonQuery return?
Although the ExecuteNonQuery returns no rows, any output parameters or return values mapped to parameters are populated with data. For UPDATE, INSERT, and DELETE statements, the return value is the number of rows affected by the command. For all other types of statements, the return value is -1.
What is difference between ExecuteReader ExecuteNonQuery and ExecuteScalar?
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.
What is use of ExecuteScalar method?
Use the ExecuteScalar method to retrieve a single value (for example, an aggregate value) from a database. This requires less code than using the ExecuteReader method, and then performing the operations that you need to generate the single value using the data returned by a SqlDataReader.
What is ExecuteScalar and ExecuteNonQuery?
9 Answers
- ExecuteScalar is typically used when your query returns a single value.
- ExecuteReader is used for any result set with multiple rows/columns (e.g., SELECT col1, col2 from sometable ).
- ExecuteNonQuery is typically used for SQL statements without results (e.g., UPDATE, INSERT, etc.).
What is the difference between ExecuteScalar and ExecuteNonQuery?
Why does ExecuteNonQuery return?
4 Answers. ExecuteNonQuery returns the number of rows affected. For UPDATE, INSERT, and DELETE statements, the return value is the number of rows affected by the command.
What is the use of ExecuteScalar () method Mcq?
– ExecuteScalar: This method returns single value. Its return type is Object. If you call ExecuteScalar method with a SQL statement that returns rows of data, the query executes but returns only the first column of the first row returned by the query.
What is difference between ExecuteNonQuery and executeQuery?
Moreover the executeQuery() is not used in . net but it is used in JAVA. ExecuteNonQuery: Executes Insert, Update, and Delete statements (DML statements) and returns the number of rows affected.
What does ExecuteNonQuery () method return?
Why does executescalar ( 0 ) always return 0?
That should do the trick. One additional suggestion is not to use count (0); instead use count (0). ‘*’ brings all data in the view; which is an unnecessary performance decrement for count function. It returns 0 because your SQL request isn’t valid.
What is the example of executescalar in SQL?
The example is passed a string representing a new value to be inserted into a table, and a string to use to connect to the data source. The function returns the new Identity column value if a new row was inserted, 0 on failure.
What should executescalar ( ) return in SQL management studio?
That should return the number of rows in the EMPLOYEE table. To double check, use the SQL management studio to execute the same code against your SQL server and see what the result is. Is it possible that your application is configured to point a different database to the one that you are viewing?
When does executescalar return nothing in Visual Basic?
According to MSDN documentation for DbCommand.ExecuteScalar: If the first column of the first row in the result set is not found, a null reference (Nothing in Visual Basic) is returned. If the value in the database is null, the query returns DBNull.Value.
