Fix ExecuteDelete with optional navigation generating invalid MySQL (error 1093)

[Copilot]

ExecuteDelete filtered through an optional reference navigation produces a LEFT JOIN, which IsValidSelectExpressionForExecuteDelete rejected (only InnerJoinExpression was accepted). EF Core then falls back to subquery pushdown — DELETE FROM t WHERE Id IN (SELECT Id FROM t ...) — which MySQL rejects with error 1093.

MySQL's multi-table DELETE syntax supports LEFT JOIN, so the fix is to accept LeftJoinExpression alongside InnerJoinExpression.

Changes

• MySqlQueryableMethodTranslatingExpressionVisitor.cs: Widen the join-type check from t is InnerJoinExpression to t is InnerJoinExpression or LeftJoinExpression

Repro

public class Child
{
    public int Id { get; set; }
    public int? ParentId { get; set; }   // optional FK
    public Parent? Parent { get; set; }
}

// Generates invalid subquery DELETE on MySQL 8
await ctx.Children.Where(c => c.Parent!.Id == parentId).ExecuteDeleteAsync();

Before (invalid — error 1093):

DELETE `c` FROM `Children` AS `c`
WHERE `c`.`Id` IN (
    SELECT `c0`.`Id` FROM `Children` AS `c0`
    LEFT JOIN `Parents` AS `p` ON `c0`.`ParentId` = `p`.`Id`
    WHERE `p`.`Id` = @parent_Id)

After (valid multi-table DELETE):

DELETE `c` FROM `Children` AS `c`
LEFT JOIN `Parents` AS `p` ON `c`.`ParentId` = `p`.`Id`
WHERE `p`.`Id` = @parent_Id

• Fixes ExecuteDelete through an optional reference navigation generates invalid MySQL (error 1093) #412