SWI-Prolog -- odbc

Documentation
- Reference manual
- Packages
  - SWI-Prolog ODBC Interface
    - The ODBC layer
      - Running SQL queries
        
        Parameterised queries
        
        odbc_prepare/4
        
        odbc_prepare/5
        
        odbc_execute/3
        
        odbc_execute/2
        
        odbc_cancel_thread/1
        
        odbc_free_statement/1

Availability::- use_module(library(odbc)).(can be autoloaded)

odbc_prepare(+Connection, +SQL, +Parameters, -Statement, +Options)

Create a statement from the given SQL (which may be a format specification as described with odbc_query/3) statement that normally has one or more parameter-indicators (?) and unify Statement with a handle to the created statement. Parameters is a list of descriptions, one for each parameter. Each parameter description is one of the following:

default

Uses the ODBC function SQLDescribeParam() to obtain information about the parameter and apply default rules. See section 2.7 for details. If the interface fails to return a type or the type is unknown to the ODBC interface a message is printed and the interface handles the type as text, which implies the user must supply an atom. The message can be suppressed using the silent(true) option of odbc_set_connection/2. An alternative mapping can be selected using the > option of this predicate described below.

SqlType(Specifier, ...)

Declare the parameter to be of type SqlType with the given specifiers. Specifiers are required for char, varchar, etc. to specify the field-width. When calling odbc_execute/[2-3], the user must supply the parameter values in the default Prolog type for this SQL type. See section 2.7 for details.

PrologType > SqlType

As above, but supply values of the given PrologType, using the type-transformation defined by the database driver. For example, if the parameter is specified as

atom > date

The use must supply an atom of the format YYYY-MM-DD rather than a term date(Year,Month,Day). This construct enhances flexibility and allows for passing values that have no proper representation in Prolog.

Variable

Interpreted as default. It unifies Variable with the PrologType > SqlType as using the types derived.^{4 The current
version does not provide the field with in SqlType. Future
versions may improve on that.} This feature is first of all intended for debugging. Using odbc_debug(1), the library prints details on the derived types.

Options defines a list of options for executing the statement. See odbc_query/4 for details. In addition, the following option is provided:

fetch(FetchType): Determine the FetchType, which is one of auto (default) to extract the result-set on backtracking or fetch to prepare the result-set to be fetched using odbc_fetch/3.