ISqlExecutor.ScalarAsync<TValue>(ISqlQueryBuilder sqlQueryBuilder, params object[] parameters) Method

.NET Standard 2.x

Asynchronously executes the SQL SELECT statement created by an ISqlQueryBuilder object and returns the first column of the first row in the result set. All other columns and rows are ignored.

Namespace: SnapObjects.Data

Assembly: SnapObjects.Data.dll

Syntax

public Task<TValue> ScalarAsync<TValue>(ISqlQueryBuilder sqlQueryBuilder, params object[] parameters)

Type Parameters

TValue

The datatype of the first column in the result set.

Parameters

sqlQueryBuilder SnapObjects.Data.ISqlQueryBuilder

A SqlQueryBuilder object which can be used to generate a SQL SELECT statement.

parameters System.Object[]

(Optional) One or more ParamValue objects which contain the values corresponding to the SQL parameter identifier names.

You can also pass the arguments directly in the order in which they appear in the SQL SELECT statement generated by sqlQueryBuilder without using the ParamValue objects.

Returns

Task<TValue>

Returns a task that represents the asynchronous operation.

Remarks

You can use parameter placeholders in the raw SQL Statement. It is recommended to use the syntax for parameter placeholders that is specific to the data source. e.g., uses @parametername for SQL Server and uses :parametername for Oracle.

Examples

The following code example demonstrates how to use the ScalarAsync<TValue> (ISqlQueryBuilder, params object[]) method to execute the SQL statement generated by an ISqlQueryBuilder object.

using System;
using System.Threading;
using System.Threading.Tasks;
using SnapObjects.Data;

namespace Appeon.ApiDoc.ISqlExecutorExamples
{
    public class ScalarAsyncExample
    {
        private readonly SchoolContext _context;
        
        public ScalarAsyncExample(SchoolContext dataContext)
        {
            // Sets the data context.
            _context = dataContext;
        }

        public async void Example3()
        { 
            // Creates a SqlQueryBuilder.
            var builder = new SqlQueryBuilder();
            
            var idParam = SqlBuilder.Parameter<int>("id");
            
            // Builds the SQL SELECT statement.
            builder.Select("Title")
                .From("Course")
                .Where("CourseID", idParam);
                
            // Asynchronously Executes the SQL statement and the first column of the
            // first row in the result set.
            int id = 2042;
            string  title = await _context.SqlExecutor.ScalarAsync<string>(builder, id);
            
            Console.WriteLine("Title: {0}", title);
            
            /*This code produces the following output:
            
                Title: Literature
            */
        }
    }
}

Applies to

.NET Standard

2.x