module Dbi:Generic database interface.sig
..end
Making a connection to a specific type of database:
module DB = Dbi_postgres
let dbh = new DB.connection "database_name"
Simple usage, returning one row:
let sth = dbh#prepare "SELECT name FROM employees WHERE empid = ?" in
sth#execute [`Int 100];
let [`String name] = sth#fetch1 in ...
Simple usage, returning multiple rows:
let sth = dbh#prepare "SELECT firstname, name FROM employees\n WHERE salary > ?" in
sth#execute [`Int 10000];
sth#iter(function
| [(`Null | `String _) as fname, `String name] ->
do_something_with fname name
| _ -> assert false);
Advanced usage, reusing prepared statements:
let sth =
dbh#prepare "INSERT INTO employees(name, salary) VALUES (?, ?)" in
List.iter(fun (name, salary) ->
sth#execute [`String name; `Int salary];
let id = sth#serial "" in
Printf.printf "Employee %s has been assigned ID %d\n" name id
) employees_list;
type
date = {
|
year : |
|
month : |
|
day : |
type
time = {
|
hour : |
|
min : |
|
sec : |
|
microsec : |
|
timezone : |
typedatetime =
date * time
module Decimal:sig
..end
typesql_t =
[ `Bigint of Big_int.big_int
| `Binary of string
| `Bool of bool
| `Date of date
| `Decimal of Decimal.t
| `Float of float
| `Int of int
| `Interval of datetime
| `Null
| `String of string
| `Time of time
| `Timestamp of datetime
| `Unknown of string ]
val sql_t_to_string : sql_t -> string
sql_t_to_string t
returns a string representation of t
following the Ocaml conventions. The aim is to offer an easy way
to print sql_t
values.val sdebug : sql_t list -> string
sdebug ss
can be used to debug the return value from a #fetch1
,
#map
or other query. It converts the sql_t list
type into a
printable form which may be printed on stderr
to aid in debugging
the actual types returned by the database.val intoption : int option -> sql_t
intoption(Some i)
returns `Int i
and
intoption None
returns `Null
.val stringoption : string option -> sql_t
stringoption(Some s)
returns `String s
and
stringoption None
returns `Null
.type
precommit_handle
type
postrollback_handle
val string_escaped : string -> string
escape_string s
escapes the string s
according to SQL rules
and surrounds it with single quotes. This should be hardly needed
as the data provided through the sql_t types will automatically be
escaped for you.val placeholders : int -> string
placeholders n
returns a string of the form "(?, ?, ..., ?)" containing
n
question marks.
Invalid_argument
if n <= 0
.exception SQL_error of string
class virtual statement :connection ->
object
..end
class virtual connection :?host:string -> ?port:string -> ?user:string -> ?password:string -> string ->
object
..end