SqlBuilder.On(string left, SqlBinaryOperator sqlOperator, ISqlBuilder sqlBuilder) Method

.NET Standard 2.x

Creates an ISqlJoinCondition object which represents a search condition that can be used when building the ON clause. Specifies a SQL expression on the left of the operator and a SQL subquery on the right.

Namespace: SnapObjects.Data

Assembly: SnapObjects.Data.dll

Syntax

 public static ISqlJoinCondition On(string left, SqlBinaryOperator sqlOperator, ISqlBuilder sqlBuilder);

Parameters

left System.String

A SQL expression on the left of the operator.

SqlBinaryOperator SnapObjects.Data.SqlBinaryOperator

An enumeration value of SqlBinaryOperator, which is the operator to test the two expressions on the left and right.

sqlBuilder SnapObjects.Data.ISqlBuilder

An ISqlBuilder object which represents a SQL subquery on the right of the operator.

Returns

SnapObjects.Data.ISqlJoinCondition

Returns the ISqlJoinCondition object which can be used to add more search conditions to the ON clause.

Examples

The following code example uses the On method to set the condition to join the "Department" table with the "Course" table.

using SnapObjects.Data;
using System;

namespace Appeon.ApiDoc.SqlBuilderExamples
{
    public class OnExample
    {
        private SchoolContext _context;

        public OnExample(SchoolContext dataContext)
        {
            // Sets Data Context.
            _context = dataContext;
        }

        public void Example6()
        {
            var sqlQueryBuilder = new SqlQueryBuilder();

            // Gets the largest department ID, and uses it as a parameter for the JOIN condition.
            var sqlBuilder = new SqlQueryBuilder();
            sqlBuilder.SelectRaw("max(DepartmentID)")
                .From("Department");

            // Defines a JOIN ON condition.
            var join = SqlBuilder
               .On("Department.DepartmentID",
                    SqlBinaryOperator.LessThan, sqlBuilder);

            // Creates a SQL statement.
            var query = sqlQueryBuilder
                .Select("Department.DepartmentID")
                .Select("Department.Name")
                .Select("Course.Title")
                .From("Department")
                .Join("Course")
                .On(join);

            // Converts to raw SQL for the database corresponding to the data context.
            string sql = query.ToSqlString(_context);

            Console.WriteLine(sql);

            /*This code example produces the following output:     
             
            SELECT
            [Department].[DepartmentID],
            [Department].[Name],
            [Course].[Title]
            FROM [Department] JOIN [Course]
            ON [Department].[DepartmentID] < (SELECT
                MAX([DepartmentID])
            FROM [Department])
            */
        }
    }
}

Applies to

.NET Standard

2.x