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Module Mysql


module Mysql: sig  end
This module provides access to MySQL databases, roughly following the C API


Database connections




Opening a connection



type dbd
database connection handle


type db = {
   dbhost : string option; (*database server host*)
   dbname : string option; (*database name*)
   dbport : int option; (*port*)
   dbpwd : string option; (*user password*)
   dbuser : string option; (*database user*)
}
Login information for a database. database. Use None for default values

val defaults : db
Login information using all defaults
val connect : db -> dbd
connect db connects to the database db and returns a handle for further user
val quick_connect : ?host:string ->
       ?database:string ->
       ?port:int -> ?password:string -> ?user:string -> unit -> dbd
Shortcut for connecting to a database with mostly default field values


Altering a connection 


val change_user : dbd -> db -> unit
change_user dbd db tries to change the current user and database. The host and port fields of db are ignored.
val quick_change : ?user:string -> ?password:string -> ?database:string -> dbd -> unit
Another shortcut
val select_db : dbd -> string -> unit
select_db Switch to a new db, using the current user and password.
val disconnect : dbd -> unit
disconnect dbd releases a database connection dbd. The handle dbd becomes invalid
val ping : dbd -> unit
ping dbd makes sure the connection to the server is up, and re-establishes it if needed.


Information about a connection 


val list_dbs : dbd -> ?pat:string -> unit -> string array option
list_db Return a list of all visible databases on the current server
val client_info : dbd -> string
Return the MySQL client library version
val host_info : dbd -> string
Return information about the server connection
val server_info : dbd -> string
Return the MySQL server version
val proto_info : dbd -> int
Return the protocol version being used


Errors 


exception Error of string
When most of the API functions fail, they raise this exception with a description of the failure.

type error_code =
| Aborting_connection
| Access_denied_error
| Alter_info
| Bad_db_error
| Bad_field_error
| Bad_host_error
| Bad_null_error
| Bad_table_error
| Blob_cant_have_default
| Blob_key_without_length
| Blob_used_as_key
| Blobs_and_no_terminated
| Cant_create_db
| Cant_create_file
| Cant_create_table
| Cant_create_thread
| Cant_delete_file
| Cant_drop_field_or_key
| Cant_find_dl_entry
| Cant_find_system_rec
| Cant_find_udf
| Cant_get_stat
| Cant_get_wd
| Cant_initialize_udf
| Cant_lock
| Cant_open_file
| Cant_open_library
| Cant_read_charset
| Cant_read_dir
| Cant_remove_all_fields
| Cant_reopen_table
| Cant_set_wd
| Checkread
| Columnaccess_denied_error
| Commands_out_of_sync
| Con_count_error
| Conn_host_error
| Connection_error
| Db_create_exists
| Db_drop_delete
| Db_drop_exists
| Db_drop_rmdir
| Dbaccess_denied_error
| Delayed_cant_change_lock
| Delayed_insert_table_locked
| Disk_full
| Dup_entry
| Dup_fieldname
| Dup_key
| Dup_keyname
| Dup_unique
| Empty_query
| Error_on_close
| Error_on_read
| Error_on_rename
| Error_on_write
| Field_specified_twice
| File_exists_error
| File_not_found
| File_used
| Filsort_abort
| Forcing_close
| Form_not_found
| Function_not_defined
| Get_errno
| Got_signal
| Grant_wrong_host_or_user
| Handshake_error
| Hashchk
| Host_is_blocked
| Host_not_privileged
| Illegal_grant_for_table
| Illegal_ha
| Insert_info
| Insert_table_used
| Invalid_default
| Invalid_group_func_use
| Invalid_use_of_null
| Ipsock_error
| Key_column_does_not_exits
| Key_not_found
| Kill_denied_error
| Load_info
| Localhost_connection
| Mix_of_group_func_and_fields
| Multiple_pri_key
| Namedpipe_connection
| Namedpipeopen_error
| Namedpipesetstate_error
| Namedpipewait_error
| Net_error_on_write
| Net_fcntl_error
| Net_packet_too_large
| Net_packets_out_of_order
| Net_read_error
| Net_read_error_from_pipe
| Net_read_interrupted
| Net_uncompress_error
| Net_write_interrupted
| Nisamchk
| No
| No_db_error
| No_raid_compiled
| No_such_index
| No_such_table
| No_such_thread
| No_tables_used
| No_unique_logfile
| Non_uniq_error
| Nonexisting_grant
| Nonexisting_table_grant
| Nonuniq_table
| Normal_shutdown
| Not_allowed_command
| Not_form_file
| Not_keyfile
| Null_column_in_index
| Old_keyfile
| Open_as_readonly
| Out_of_memory
| Out_of_resources
| Out_of_sortmemory
| Outofmemory
| Parse_error
| Password_anonymous_user
| Password_no_match
| Password_not_allowed
| Primary_cant_have_null
| Ready
| Record_file_full
| Regexp_error
| Requires_primary_key
| Server_gone_error
| Server_handshake_err
| Server_lost
| Server_shutdown
| Shutdown_complete
| Socket_create_error
| Stack_overrun
| Syntax_error
| Table_cant_handle_auto_increment
| Table_cant_handle_blob
| Table_exists_error
| Table_must_have_columns
| Table_not_locked
| Table_not_locked_for_write
| Tableaccess_denied_error
| Tcp_connection
| Textfile_not_readable
| Too_big_fieldlength
| Too_big_rowsize
| Too_big_select
| Too_big_set
| Too_long_ident
| Too_long_key
| Too_long_string
| Too_many_delayed_threads
| Too_many_fields
| Too_many_key_parts
| Too_many_keys
| Too_many_rows
| Too_many_tables
| Udf_exists
| Udf_no_paths
| Unexpected_eof
| Unknown_character_set
| Unknown_com_error
| Unknown_error
| Unknown_host
| Unknown_procedure
| Unknown_table
| Unsupported_extension
| Update_info
| Update_without_key_in_safe_mode
| Version_error
| Wrong_auto_key
| Wrong_column_name
| Wrong_db_name
| Wrong_field_spec
| Wrong_field_terminators
| Wrong_field_with_group
| Wrong_group_field
| Wrong_host_info
| Wrong_key_column
| Wrong_mrg_table
| Wrong_outer_join
| Wrong_paramcount_to_procedure
| Wrong_parameters_to_procedure
| Wrong_sub_key
| Wrong_sum_select
| Wrong_table_name
| Wrong_value_count
| Wrong_value_count_on_row
| Yes
Possible error codes from a failed operation that doesn't throw an exception


type status =
| StatusOK (*The query was successful*)
| StatusEmpty (*The query was successful, but found no results*)
| StatusError of error_code (*There was some problem with the query*)
The status of a query

val status : dbd -> status
status dbd returns the status of the last action on dbd
val errno : dbd -> error_code
errno dbd returns the error_code for the last action on dbd. Useful when you know there's an error, to avoid an extra layer of matching in status
val errmsg : dbd -> string option
errmsg dbd returns an error message in case the last operation on dbd failed


Queries




Making a query



type result
handle to access the result of a query

val exec : dbd -> string -> result
exec dbd str executes a SQL statement and returns a handle to obtain the result. Check status for errors!


Getting the results of a query 


val fetch : result -> string option array option
fetch result returns the next row from a result as Some a or None in case there is no next result. The array a contains the values from the current row, where NULL values are denoted by None. Use column to fetch single values by field name instead of by position
val to_row : result -> int64 -> unit
to_row result row sets the current row.
Raises Invalid_argument if the row is out of range.
val size : result -> int64
size result returns the size of the actual result set (number of rows)

iter result f applies f to each row of result in turn, starting from the first. iter_col applies f to the value of the named column in every row.

The iter versions return unit, the map versions return a list of the results of all the function applications. If there were no rows in the result, returns an empty list.

The iter forms are all tail-recursive, so they can be used with any size of results. The map forms are tail-recursive, but take up space with the list they build.

val iter : result -> f:(string option array -> unit) -> unit
val iter_col : result -> key:string -> f:(string option -> unit) -> unit
val iter_cols : result -> key:string array -> f:(string option array -> unit) -> unit
val map : result -> f:(string option array -> 'a) -> 'a list
val map_col : result -> key:string -> f:(string option -> 'a) -> 'a list
val map_cols : result -> key:string array -> f:(string option array -> 'a) -> 'a list
val column : result -> key:string -> row:string option array -> string option
Returns one field of a result row based on column name.


Metainformation about a result set



type dbty =
| IntTy
| FloatTy
| StringTy
| SetTy
| EnumTy
| DateTimeTy
| DateTy
| TimeTy
| YearTy
| TimeStampTy
| UnknownTy
| Int64Ty
| BlobTy
| DecimalTy
The type of a database field. Each of these represents one or more MySQL data types.


type field = {
   name : string; (*Name of the field*)
   table : string option; (*Table name, or None if a constructed field*)
   def : string option; (*Default value of the field*)
   ty : dbty; (*The type of data stored in the field*)
   max_length : int; (*Maximum width of field for the result set*)
   flags : int; (*Flags set*)
   decimals : int; (*Number of decimals for numeric fields*)
}
The type that describes a field of a table or result

val pretty_type : dbty -> string
Turn a field-type type into a string for printing
val affected : dbd -> int64
affected result returns the number of rows changed by the last UPDATE, or deleted by the last DELETE, or added by the last INSERT, or the number of rows returned by the last SELECT
val fields : result -> int
fields result returns the number of fields in a row
val names : result -> string array
names result returns an array of the field names for the current result
val types : result -> dbty array
types result returns an array with the MySQL types of the current result
val fetch_field : result -> field option
Returns the information on the next field
val fetch_fields : result -> field array option
Returns information on all the fields
val fetch_field_dir : result -> int -> field option
Returns information on a specific field, with the first field numbered 0


Working with MySQL data types 


val escape : string -> string
escape str returns the same string as str in MySQL syntax with special characters quoted to not confuse the MySQL parser

xxx2ml str decodes a MySQL value of type xxx into a corresponding OCaml value

val int2ml : string -> int
Use for all MySQL signed integer types but BIGINT
val decimal2ml : string -> string
val int322ml : string -> int32
val nativeint2ml : string -> nativeint
val int642ml : string -> int64
val float2ml : string -> float
Use for MySQL FLOAT, DOUBLE and REAL types
val str2ml : string -> string
Use for MySQL CHAR and VARCHAR types
val enum2ml : string -> string
val blob2ml : string -> string
Use for all MySQL BLOB and TEXT types
val set2ml : string -> string list
val datetime2ml : string -> int * int * int * int * int * int
val date2ml : string -> int * int * int
val time2ml : string -> int * int * int
val year2ml : string -> int
val timestamp2ml : string -> int * int * int * int * int * int

Not yet supported: DECIMAL and NUMERIC

val opt : ('a -> 'b) -> 'a option -> 'b option
opt f v applies f to optional value v. Use this to fetch data of known type from database fields which might be NULL: opt int2ml str
val not_null : ('a -> 'b) -> 'a option -> 'b
not_null f v applies f to Some v. Use this to fetch data of known type from database fields which never can be NULL: not_null int2ml str

ml2xxx v encodes v into MySQL syntax.

val ml2str : string -> string
val ml2blob : string -> string
val ml2int : int -> string
val ml2decimal : string -> string
val ml322int : int32 -> string
val ml642int : int64 -> string
val ml2float : float -> string
val ml2enum : string -> string
val ml2set : string list -> string
val ml2datetime : int * int * int * int * int * int -> string
val ml2datetimel : year:int -> month:int -> day:int -> hour:int -> min:int -> sec:int -> string
val ml2date : int * int * int -> string
val ml2datel : year:int -> month:int -> day:int -> string
val ml2time : int * int * int -> string
val ml2timel : hour:int -> min:int -> sec:int -> string
val ml2year : int -> string
val ml2timestamp : int * int * int * int * int * int -> string
val ml2timestampl : year:int -> month:int -> day:int -> hour:int -> min:int -> sec:int -> string
val values : string list -> string
values vs takes a list of strings and returns a string "(a,b,c ..)" where values are separated by comma and the whole list is enclosed into parentheses. This is useful to construct SQL `insert ... values ( .. )' statements