Open Client and Open Server support tables with more than 255 columns and column sizes in excess of 255 bytes or 255-byte binary data.
To support wide tables, the client sends a login packet to the server along with a capability packet. Possible ct_capability parameters include:
CS_WIDETABLE – a request capability that a client sends to the server indicating the client has the capability to receive larger data table formats.
CS_NOWIDETABLE – a response capability that a client sends to the server to have the server disable wide table support for this particular connection.
If the version of the application is set to CS_VERSION_125 or later, Client-Library always sends CS_WIDETABLE capability to the server; the application does not have control of the request capability. However, the application can set CS_NOWIDETABLE response capability before the connection is established to specifically request the server not to enable wide table capabilities.
The syntax of ct_capability is:
CS_RETCODE ct_capability (connection, action, type, capability, value)
CS_CONNECTION *connection;
CS_INT action;
CS_INT type;
CS_INT capability;
CS_VOID *value;
where the values of type are CS_WIDETABLE or CS_NOWIDETABLE.
If you do not want to enable wide table support, you can set the CS_NOWIDETABLE response capability before calling the ct_connect routine. This must be done before connecting to the server.
...
CS_BOOL boolv = CS_TRUE
...
retcode = ct_capability (*conn_ptr, CS_SET, CS_CAP_RESPONSE, CS_NOWIDETABLES, &boolv);
...
ct_dynamic() with CS_CURSOR_DECLARE supports the flags CS_PREPARE, CS_EXECUTE, and CS_EXEC_IMMEDIATE to prepare and execute dynamic SQL statements that reference the 1024-column limit of Adaptive Server Enterprise 12.5.
ct_param() can be used to pass as many as 1024 arguments to a dynamic SQL statement.
If the column data you are retrieving is in excess of CS_MAX_CHAR (256 characters or 256 binary data), you must edit the CS_DATAFMT structure field datafmt.maxlength definition to the maximum length, in bytes, of the data that you are retrieving. Otherwise, you get a truncation error.
If you expect wider columns in the client program, change the column array size in the application program.
For example, if the application expects a column that is 300 bytes wide, then the column should mention CS_CHAR col1[300] at an appropriate place. Assign an appropriate length-of-character datatype, to the maxlength parameter of the CS_DATAFMT structure for RPC applications if the column is more than 255 bytes. The following is recommended for the CS_DATAFMT parameter:
datafmt.datatype = CS_LONGCHAR_TYPE datafmt.maxlength = sizeof(col1)
The following example is a small ctlib program using the pubs2 database.
Alter the authors table and add a column “comment” declare as a varchar(500):
1>alter table authors add comment varchar(500) null 2>go
Update the new column within the table:
1>update authors set comment = replicate (substring(state,1,1), 500) 2>go /* This SQL command will update the comment column with a replicate of 500 times the first letter of the state for each row. */
Modify the example.h file to set the “new limits” capabilities:
#define EX_CTLIB_VERSION CS_VERSION_155
Update the exutils.h file and reset the MAX_CHAR_BUF to 16384 (16K).
Recompile and link ctlib using 15.5 headers and libraries.
Execute and test on an Adaptive Server Enterprise version 12.5 or later Xk page size server.
If you set CS_VERSION_155, you see the following (only displays the last 2 rows):
Heather McBadden 95688 CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC Anne Ringer 84152 UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU
Update the example.h file and reset ctlib to CS_VERSION_120. Recompile and link using OCS-15_5 headers and libraries.
If you execute the same program without setting CS_VERSION_155
first, you retrieve only the first 255 bytes of the comment column
and cannot retrieve wide columns, even if you are using version
12.5 or later of Adaptive Server Enterprise and OCS 15.5
libraries.
Open Client message:
Message number: LAYER = (1) ORIGIN = (4) SEVERITY = (1) NUMBER = (132) Message String: ct_fetch(): user api layer: internal common library error: The bind of result set item 4 resulted in truncation. Error on row 21. Heather McBadden 95688 CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC CCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC
Open Client message:
Message number: LAYER = (1) ORIGIN = (4) SEVERITY = (1) NUMBER = (132) Message String: ct_fetch(): user api layer: internal common library error: The bind of result set item 4 resulted in truncation. Error on row 22. Anne Ringer 84152 UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU
Wide-table support is activated automatically if:
The client is set to CS_VERSION_125 or later
It is linked with Open Client Server 12.5 or later, and
The Adaptive Server Enterprise to which it is connected has the capabilities to handle wide tables.
If the Client-Library application’s version string is not set to CS_VERSION_125 or later, and it is linked to an Open Client and Open Server 12.5 or later, the application does not support the extended limits and there is no behavioral change.
If the Open Client and Open Server version 15.0 or 15.5 connects to a pre-12.5 Adaptive Server Enterprise, the server returns a capability bit of 0, indicating that it does not support wide tables; the connection is still made but there are no behavioral changes.
If a pre-12.5 version of Open Client and Open Server connects to an Adaptive Server Enterprise 15.0, the new limits are not enabled. However, if the Adaptive Server Enterprise determines that it must send a wide-table format to an older client, the data is truncated and sent.
Adaptive Server Enterprise version 11.0 and later returns
a mask length of 0 for any mask length in excess of 7 bytes. If
the connection request receives a capability mask of 0, you see
this error message:
ct_connect(): protocol specific layer: external error: “This server does not accept new larger cpability mask, the original cap mask will be used.”
and the extended limits are not enabled.
The CS_RES_NOXNLMETADATA response capability improves server and client application performance by optimizing the information type and structure that server applications send to client applications. You can use CS_RES_NOXNLMETADATA to inform your server to not send metadata such as Column Label, Catalog Name, Schema Name, and Table Name when this information is not needed.
By default, CS_RES_NOXNLMETADATA is on for applications in which the version is set to CS_VERSION_125, CS_VERSION_150, or CS_VERSION_155.
