将SQL（左外部联接）转换为LINQ

Question

I am having trouble converting a Oracle Sql Query with multiple LEFT OUTER JOIN to LINQ. My attempts don't return the expected results. Could somebody help to convert the SQL Query below to LINQ.

string currentCulture = Culture.GetCulture();
string query = @"SELECT *
               FROM CTGLBL g, CTTGLBL ct, CTLANG lang
               WHERE g.sysctglbl = ct.sysctglbl(+) AND 
                     ct.sysctlang = lang.sysctlang (+) AND
                     NVL(lang.activeflag, 1)= 1 AND
                     (ISOCODE LIKE '" + currentCulture + "%' OR ISOCODE IS NULL)";

ISOCODE belongs to CTLANG Table.

ps. I can't use tools like LINQPAD or Linqer.

Answer 1

But a better practice for your sql (and here converted to linq) is to use join to join tables and not the where :

string currentCulture = Culture.GetCulture();

var result = from g in CTGLBL
             join ct in CTTGLBL on g.sysctglbl equals ct.sysctglbl into ctj
             from ct in ctj.DefaultIfEmpty()
             join lang in CTLANG on ct.sysctlang equals lang.sysctlang into langj
             from lang in langj.DefaultIfEmpty()
             where (lang == null ?  1 : (lang.activeflag ?? 1)) == 1 &&
                 (lang?.ISOCODE.StartsWith(currentCulture) || lang?.ISOCODE == null)
             select new { g, ct, lang };

You can also have a "nested select" for your CTLANG like this:

string currentCulture = Culture.GetCulture();

var result = from g in CTGLBL
             join ct in CTTGLBL on g.sysctglbl equals ct.sysctglbl into ctj
             from ct in ctj.DefaultIfEmpty()
             join lang in CTTGLBL.Where(lang => lang.activeflag ?? 1 == 1 &&
                                                  (lang.ISOCODE.Contains(currentCulture) ||
                                                   lang.ISOCODE == null))
             on ct.sysctlang equals lang.sysctlang into langj
             from lang in langj.DefaultIfEmpty()
             select new { g, ct, lang };

Answer 2

(What I see is a left join, not right)

Assuming you have the proper relations between the tables in your schema, with SQL server (Linq TO SQL) this would work, not sure if it would supported for Oracle:

string currentCulture = Culture.GetCulture();

var data = from g in db.CTGLBL
           from ct in g.CTTGLBL.DefaultIfEmpty()
           from lang in g.CTLANG.DefaultIfEmpty()
           where !g.CTLANG.Any() || 
                 ( lang.activeflag == 1 &&
                   lang.ISOCODE.StartsWith(currentCulture))
           select new {g, ct, lang};