CommandText for IUpdatable/ISelectInsertable/IValueInsertable

• IUpdatable<T>
• ISelectInsertable<T, TTarget>
• IValueInsertable<T>

For each of the above, is there a way to get the command text for before they are executed & without modifying the database?

I know I can get the text of the last command from a DataConnection by using LastQuery after the command has been executed, but I need it before.

IQueryable<T>.ToString() seems to work for select commands.

The following works using transactions with rollback calls, but this it far from ideal and obvious wouldn’t be used production code:

public static class DataConnectionExtensions {

    public static string LastQueryUpdatable = string.Empty;
    public static string LastQuerySelectInsertable = string.Empty;
    public static string LastQueryValueInsertable = string.Empty;

    public static string LastQuery<T>(this DataConnection dataConnection, IUpdatable<T> updatable) {
      var sql = $"Cannot get {nameof(LastQuery)} for {updatable}";
      using(var t = dataConnection.BeginTransaction()) {
        updatable.Update();
        sql = dataConnection.LastQuery;
        t.Rollback();
      }
      LastQueryUpdatable = sql;
      return sql;
    }

    public static string LastQuery<T, TTarget>(this DataConnection dataConnection, ISelectInsertable<T, TTarget> selectInsertable) {
      var sql = $"Cannot get {nameof(LastQuery)} for {selectInsertable}";
      using(var t = dataConnection.BeginTransaction()) {
        selectInsertable.Insert();
        sql = dataConnection.LastQuery;
        t.Rollback();
      }
      LastQuerySelectInsertable = sql;
      return sql;
    }

    public static string LastQuery<T>(this DataConnection dataConnection, IValueInsertable<T> valueInsertable) {
      var sql = $"Cannot get {nameof(LastQuery)} for {valueInsertable}";
      using(var t = dataConnection.BeginTransaction()) {
        valueInsertable.Insert();
        sql = dataConnection.LastQuery;
        t.Rollback();
      }
      LastQueryValueInsertable = sql;
      return sql;
    }

}

[to11mtm]

Just adding for another use case…

Sometimes I have to make SQL for certain Insert or update statements that are not executed via code (i.e. for Rollout/rollback type scripts.) Getting these strings lets me use Linq2Db in Linqpad to generate the SQL for these scripts.

[sdanyliv]

Good point, maybe it is good to add additional API for script generation, for example with inlined parameters. I’m also doing such SQL generation, but usually copy SQL from debugger.