ISqlQueryBuilder.Union(string sqlRaw, string builderAlias) Method

.NET Standard 2.x

Uses UNION to combine the result set of the current SQL SELECT statement with the result set of another raw SQL SELECT statement; and specifies an alias for the raw SQL SELECT statement.

Namespace: SnapObjects.Data

Assembly: SnapObjects.Data.dll

Syntax

  ISqlQueryBuilder Union(string sqlRaw, string builderAlias);

Parameters

sqlRaw System.String

The raw SQL SELECT whose result set is to be combined with the result set of the current SQL query.

builderAlias System.String

The alias of the raw SQL SELECT statement.

Returns

SnapObjects.Data.ISqlQueryBuilder

Returns the current ISqlQueryBuilder object.

Examples

The following code example demonstrates how to use the Union(ISqlQueryBuilder queryBuilder, string builderAlias) method to merge the result sets of two or more SQL SELECT statements and sets an alias for it; it sorts the records in default order and does not include duplicate rows. These SELECT statements must have the same number of columns of the same data type and in the same selected order.

using SnapObjects.Data;
using System;

namespace Appeon.ApiDoc.ISqlQueryBuilderExamples
{
    public class UnionExample
    {
        private SchoolContext _context;

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

        public void Example4()
        {

            // Declares SqlQueryBuilder. 
            var sqlbuilder = new SqlQueryBuilder();

            sqlbuilder.Select("courseid", "courseid")
                .Select("url", "address")
                .From("OnlineCourse", "online");

            // The SELECT statement to be merged with is a raw SQL string.
            // Make sure the column number, data type, and the selected order are the same for these statements.
            // Sets the alias of the merged statement as "test".
            sqlbuilder.Union("select courseid as courseid, location as address" +
                " from OnsiteCourse", "test");

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

            Console.WriteLine(sql);
            
            /*This code produces the following output:
            
            SELECT
            [courseid] AS [courseid],
            [url] AS [address]
            FROM [OnlineCourse] AS [online]
            UNION (SELECT
            [courseid] AS [courseid],
            [location] AS [address]
            FROM [OnsiteCourse])
            */
        }
    }
}

Applies to

.NET Standard

2.x