Namespace eQuantic.Core.Data.Query

Db: Query function markers — call them inside a filter lambda and the interpreter translates them to the store's native function (LIKE, EXTRACT/YEAR, …) through the dialect's function registry. Every marker also has a real C# implementation with the same semantics, so a dialect that has no translation degrades the clause to the gated client-side residual instead of failing — the same rule applies to the markers you write yourself: give them a real body, register a translation with Functions.Map(...), and they behave exactly like these.

Union: The entry point for composing a typed UNION/UNION ALL: each branch reads one entity type, optionally filtered, projected into the common result shape — an anonymous type or a member-init POCO whose members are entity members or constants (constants tag which branch a row came from). Combine branches with All<TResult>(params UnionBranch<TResult>[]) (keep duplicates) or Distinct<TResult>(params UnionBranch<TResult>[]) (SQL UNION semantics), and run the query on a unit of work that implements IUnionQueryRunner.

UnionBranch: One composed union branch: the entity type, its filters and its projection into the common shape.

UnionQuery<TResult>: A runnable union: the branches, the combine mode, and the combined ordering and paging.

UnionSource<TEntity>: A union branch under composition: the entity source, its filters, and finally its projection.