Orville.PostgreSQL.Execution.Delete

Functions for working with executable DELETE statements. The Delete type is a value that can be passed around and executed later. The Delete is directly associated with the presence of a returning clause and how to decode any rows returned by that clause. This means it can be safely executed via executeDelete or executeDeleteReturnEntities as appropriate. It is a lower-level API than the entity delete functions in Orville.PostgreSQL.Execution.EntityOperations, but not as primitive as Orville.PostgreSQL.Expr.Delete.

Since: 1.0.0.0

Documentation

data Delete readEntity returningClause

Represents a DELETE statement that can be executed against a database. A Delete has a SqlMarshaller bound to it that, when the delete returns data from the database, will be used to decode the database result set when it is executed.

Since: 1.0.0.0

deleteFromDeleteExpr :: Delete readEntity returningClause -> DeleteExpr

Extracts the query that will be run when the delete is executed. Normally you don't want to extract the query and run it yourself, but this function is useful to view the query for debugging or query explanation.

Since: 1.0.0.0

executeDelete :: MonadOrville m => Delete readEntity NoReturningClause -> m Int

Executes the database query for the Delete and returns the number of rows affected by the query.

Since: 1.0.0.0

executeDeleteReturnEntities :: MonadOrville m => Delete readEntity ReturningClause -> m [readEntity]

Executes the database query for the Delete and uses its SqlMarshaller to decode the rows (that were just deleted) as returned via a RETURNING clause.

Since: 1.0.0.0

deleteFromTableReturning :: TableDefinition key writeEntity readEntity -> Maybe BooleanExpr -> Delete readEntity ReturningClause

Builds a Delete that will delete all of the writable columns described in the TableDefinition and return the data as seen by the database. This is useful for getting database-managed columns such as auto-incrementing identifiers and sequences.

Since: 1.0.0.0

deleteFromTable :: TableDefinition key writeEntity readEntity -> Maybe BooleanExpr -> Delete readEntity NoReturningClause

Builds a Delete that will delete all of the writable columns described in the TableDefinition without returning the data as seen by the database.

Since: 1.0.0.0

rawDeleteExpr :: ReturningOption returningClause -> AnnotatedSqlMarshaller writeEntity readEntity -> DeleteExpr -> Delete readEntity returningClause

Builds a Delete that will execute the specified query and use the given SqlMarshaller to decode it. It is up to the caller to ensure that the given DeleteExpr makes sense and returns a result that the SqlMarshaller can decode.

This is the lowest level of escape hatch available for Delete. The caller can build any query that Orville supports using the expression-building functions, or use RawSql.fromRawSql to build a raw DeleteExpr. It is expected that the ReturningOption given matches the DeleteExpr. This level of interface does not provide an automatic enforcement of the expectation, however failure is likely if that is not met.

Since: 1.0.0.0