How to combine firstname and lastname in SQL and search with LIKE in C#

How to combine firstname and lastname in SQL and search with LIKE in C#

Assuming you have a Customers table in your SQL database with FirstName and LastName columns, you can combine them into a single FullName column using the CONCAT function in SQL:

SELECT CONCAT(FirstName, ' ', LastName) AS FullName FROM Customers

This will return a result set that includes a FullName column that contains the concatenated first and last names.

To search for customers based on their full name using the LIKE operator, you can use a parameterized SQL query in your C# code:

string searchTerm = "John Smith"; string query = "SELECT CONCAT(FirstName, ' ', LastName) AS FullName FROM Customers WHERE CONCAT(FirstName, ' ', LastName) LIKE @searchTerm"; using (SqlConnection connection = new SqlConnection(connectionString)) { SqlCommand command = new SqlCommand(query, connection); command.Parameters.AddWithValue("@searchTerm", "%" + searchTerm + "%"); connection.Open(); SqlDataReader reader = command.ExecuteReader(); while (reader.Read()) { string fullName = reader["FullName"].ToString(); // Do something with the full name } reader.Close(); }

In this example, we define a searchTerm variable that contains the search term we want to look for in the customers' full names. We then construct a parameterized SQL query that selects the customers' full names and filters them based on the search term using the LIKE operator.

We use the AddWithValue method to add a parameter to the SQL query, which is set to the search term with wildcard characters (%) added to the beginning and end of the string. This ensures that we get partial matches for the search term.

We then execute the SQL query using a SqlConnection object, read the results using a SqlDataReader, and extract the full names from the FullName column of the result set.

Examples

  1. How to search for a person by combining firstname and lastname using LIKE in SQL with C#?

    • Code Implementation:
      string searchTerm = "John Doe"; var query = "SELECT * FROM People WHERE CONCAT(firstname, ' ', lastname) LIKE @SearchTerm"; var result = context.Database.SqlQuery<Person>(query, new SqlParameter("@SearchTerm", "%" + searchTerm + "%")).ToList();
    • Description: Searches for a person by combining firstname and lastname using LIKE in a SQL query executed with Entity Framework in C#.

  2. How to handle case-insensitive searches for combined firstname and lastname with LIKE in C#?

    • Code Implementation:
      string searchTerm = "john doe"; var query = "SELECT * FROM People WHERE CONCAT(firstname, ' ', lastname) COLLATE SQL_Latin1_General_CP1_CI_AS LIKE @SearchTerm"; var result = context.Database.SqlQuery<Person>(query, new SqlParameter("@SearchTerm", "%" + searchTerm + "%")).ToList();
    • Description: Performs a case-insensitive search for a person by combining firstname and lastname using LIKE in a SQL query.

  3. How to handle wildcard characters when searching for a person by combined name in C#?

    • Code Implementation:
      string searchTerm = "Jo* Doe"; searchTerm = searchTerm.Replace("*", "%"); var query = "SELECT * FROM People WHERE CONCAT(firstname, ' ', lastname) LIKE @SearchTerm"; var result = context.Database.SqlQuery<Person>(query, new SqlParameter("@SearchTerm", searchTerm)).ToList();
    • Description: Allows the use of wildcard characters (e.g., *) in the search term when combining firstname and lastname using LIKE.

  4. How to search for a person by combined name with firstname and lastname in a specific order in C#?

    • Code Implementation:
      string searchTerm = "John Doe"; var query = "SELECT * FROM People WHERE CONCAT(firstname, ' ', lastname) = @SearchTerm"; var result = context.Database.SqlQuery<Person>(query, new SqlParameter("@SearchTerm", searchTerm)).ToList();
    • Description: Searches for a person with a specific combined name (e.g., "John Doe") using an exact match in the SQL query.

  5. How to perform a partial search for a person by combined name in C#?

    • Code Implementation:
      string searchTerm = "John"; var query = "SELECT * FROM People WHERE CONCAT(firstname, ' ', lastname) LIKE @SearchTerm"; var result = context.Database.SqlQuery<Person>(query, new SqlParameter("@SearchTerm", "%" + searchTerm + "%")).ToList();
    • Description: Performs a partial search for a person by combining firstname and lastname using LIKE with a wildcard for partial matches.

  6. How to search for a person by combining firstname and lastname in SQL and limit the number of results in C#?

    • Code Implementation:
      string searchTerm = "John Doe"; var query = "SELECT TOP 10 * FROM People WHERE CONCAT(firstname, ' ', lastname) LIKE @SearchTerm"; var result = context.Database.SqlQuery<Person>(query, new SqlParameter("@SearchTerm", "%" + searchTerm + "%")).ToList();
    • Description: Limits the search results to the top 10 when searching for a person by combined firstname and lastname using LIKE in SQL.

  7. How to handle null values when combining firstname and lastname for search in C#?

    • Code Implementation:
      string searchTerm = "John Doe"; var query = "SELECT * FROM People WHERE CONCAT(ISNULL(firstname, ''), ' ', ISNULL(lastname, '')) LIKE @SearchTerm"; var result = context.Database.SqlQuery<Person>(query, new SqlParameter("@SearchTerm", "%" + searchTerm + "%")).ToList();
    • Description: Handles null values for firstname or lastname when combining them for search using LIKE in SQL.

  8. How to search for a person by combined name with firstname and lastname and specify a case-sensitive comparison in C#?

    • Code Implementation:
      string searchTerm = "John Doe"; var query = "SELECT * FROM People WHERE CONCAT(firstname, ' ', lastname) COLLATE SQL_Latin1_General_CP1_CS_AS LIKE @SearchTerm"; var result = context.Database.SqlQuery<Person>(query, new SqlParameter("@SearchTerm", "%" + searchTerm + "%")).ToList();
    • Description: Performs a case-sensitive search for a person by combining firstname and lastname using LIKE in a SQL query.

  9. How to search for a person by combined name with firstname and lastname and exclude specific records in C#?

    • Code Implementation:
      string searchTerm = "John Doe"; var query = "SELECT * FROM People WHERE CONCAT(firstname, ' ', lastname) LIKE @SearchTerm AND Id NOT IN (1, 2, 3)"; var result = context.Database.SqlQuery<Person>(query, new SqlParameter("@SearchTerm", "%" + searchTerm + "%")).ToList();
    • Description: Excludes specific records (e.g., with Id values 1, 2, 3) when searching for a person by combined firstname and lastname using LIKE.

  10. How to search for a person by combined name with firstname and lastname and order the results in C#?

    • Code Implementation:
      string searchTerm = "John Doe"; var query = "SELECT * FROM People WHERE CONCAT(firstname, ' ', lastname) LIKE @SearchTerm ORDER BY lastname, firstname"; var result = context.Database.SqlQuery<Person>(query, new SqlParameter("@SearchTerm", "%" + searchTerm + "%")).ToList();
    • Description: Orders the search results by lastname and firstname when searching for a person by combined firstname and lastname using LIKE.

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