IQueryAndOrBuilder<TModel>.OrWhereNotExists(ISqlBuilder sqlBuilder) Method

.NET Standard 2.x

Adds the OR logical operator and a search condition to the WHERE clause; and uses the NOT EXISTS operator to test if the record returned from a subquery does not exist.

Namespace: SnapObjects.Data

Assembly: SnapObjects.Data.dll

Syntax

  IQueryAndOrBuilder<TModel> OrWhereNotExists(ISqlBuilder sqlBuilder);

Parameters

sqlBuilder SnapObjects.Data.ISqlBuilder

An ISqlBuilder object which represents a SQL subquery on the right of the NOT EXISTS operator.

Returns

IQueryAndOrBuilder<TModel>

Returns anIQueryAndOrBuilder<TModel> object which can be used to add more search conditions to the current WHERE clause.

Examples

The following code example demonstrates how to use the OrWhereNotExists method to add an OR NOT EXISTS condition to the WHERE clause. In this example, the NOT EXISTS condition specifies that the data must not exist in the result set of a subquery.

using Appeon.ApiDoc.Models.School;
using SnapObjects.Data;
using System;
using System.Threading.Tasks;

namespace Appeon.ApiDoc.IQueryAndOrBuilderExamples
{
    public class OrWhereNotExistsExample
    {
        private SchoolContext _context;
        
        public OrWhereNotExistsExample(SchoolContext dataContext)
        {
            // Sets Data Context
            _context = dataContext;
        }

        public async Task<int> Example()
        {
            // Get a QueryBuilder.
            var Builder = _context.SqlModelMapper.GetQueryBuilder<Department>();
            
            // Defines a subquery.
            var subsqlbuilder = new SqlQueryBuilder();
            subsqlbuilder.Select("1")
                .From("Department")
                .Where("departmentid", SqlBuilder.Parameter<int>("id"));
                
            var subsqlbuilder2 = new SqlQueryBuilder();
            subsqlbuilder2.Select("1")
                .From("Department")
                .Where("departmentid", SqlBuilder.Parameter<int>("id2"));
                
            // Specifies the WHERE EXIST condition:
            // the data exists in the result set of the subquery.
            Builder.WhereNotExists(subsqlbuilder)
                   .OrWhereNotExists(subsqlbuilder2);
                   
            // Data with departmentID = 3 does not exist
            // and Data with departmentID = 4  exists.
            var result = (await Builder.LoadAsync(3, 4)).ToList();
            
            if (result.Count != 0)
            {
                Console.WriteLine("Can execute LoadAsync.");
            }
            else
            {
                Console.WriteLine("Cannot execute LoadAsync.");
            }
            
            return result.Count;
            
            /*This code example produces the following output:   
             
                Can execute LoadAsync.
            */
        }
    }
}

Example Refer To

Model Class: Department

Applies to

.NET Standard

2.x