spec_sql_list_objects: spec_sql_list_objects

In DBItest: Testing DBI Backends

spec_sql_list_objects

Description

spec_sql_list_objects

Value

dbListObjects() returns a data frame with columns table and is_prefix (in that order), optionally with other columns with a dot (.) prefix. The table column is of type list. Each object in this list is suitable for use as argument in dbQuoteIdentifier(). The is_prefix column is a logical. This data frame contains one row for each object (schema, table and view) accessible from the prefix (if passed) or from the global namespace (if prefix is omitted). Tables added with dbWriteTable() are part of the data frame. As soon a table is removed from the database, it is also removed from the data frame of database objects.

The same applies to temporary objects if supported by the database.

The returned names are suitable for quoting with dbQuoteIdentifier().

Failure modes

An error is raised when calling this method for a closed or invalid connection.

Specification

The prefix column indicates if the table value refers to a table or a prefix. For a call with the default prefix = NULL, the table values that have is_prefix == FALSE correspond to the tables returned from dbListTables(),

The table object can be quoted with dbQuoteIdentifier(). The result of quoting can be passed to dbUnquoteIdentifier(). (We have to assume that the resulting identifier is a table, because one cannot always tell from a quoted identifier alone whether it is a table or a schema for example. As a consequence, the quote-unquote roundtrip only works for tables (possibly schema-qualified), but not for other database objects like schemata or columns.) The unquoted results are equal to the original table object. (For backends it may be convenient to use the Id class, but this is not required.)

Values in table column that have is_prefix == TRUE can be passed as the prefix argument to another call to dbListObjects(). For the data frame returned from a dbListObject() call with the prefix argument set, all table values where is_prefix is FALSE can be used in a call to dbExistsTable() which returns TRUE.

See Also

Other sql specifications: spec_sql_append_table, spec_sql_create_table, spec_sql_exists_table, spec_sql_list_fields, spec_sql_list_tables, spec_sql_quote_identifier, spec_sql_quote_literal, spec_sql_quote_string, spec_sql_read_table, spec_sql_remove_table, spec_sql_unquote_identifier, spec_sql_write_table

DBItest documentation built on Oct. 18, 2022, 9:09 a.m.