Using the SQLCA

The SQLCA is used for communicating information between the application program and ALLBASE/SQL. SQL places information in the SQLCA each time it is called. Since there is no guarantee that information from one call to SQL will be present after the next call to SQL, any information needed from the SQLCA must be obtained after each call to ALLBASE/SQL.

Every ALLBASE/SQL Pascal main program must have the SQLCA declared in the global declaration section. You can use the INCLUDE command to declare the SQLCA:

   EXEC SQL INCLUDE SQLCA;

When the Pascal preprocessor parses this command, it inserts the following type definition into the modified source file:

   sqlca: Sqlca_Type

You can also use this type definition in the global declaration section of your source file instead of using the INCLUDE command to declare the SQLCA.

The Pascal preprocessor generates the following record declaration for sqlca_type in the type include file. This portion of the type include file contains some conditional statements. The entire type include file can be found in the chapter, "Using the ALLBASE/SQL Pascal Preprocessor." (It is recommended that you initialize the SqlcaId element to blanks, one time, before the first SQL statement in your program.)

     SQLCA_TYPE = record                                                   

       SQLCAID : packed array [1..8] of char;                              

       SQLCABC : integer;                                                  

       SQLCODE : integer;                                                  

       SQLERRM : string[255];                                              

       SQLERRP : packed array [1..8] of char;                              

       SQLERRD : array [1..6] of integer;                                  

   $if 'XOPEN_SQLCA'$                                                      

       SQLWARN0, SQLWARN1, SQLWARN2,                                       

       SQLWARN3, SQLWARN4, SQLWARN5,                                       

       SQLWARN6, SQLWARN7 : char;                                          

   $else$                                                                  

       SQLWARN : packed array [0..7] of char;                              

   $endif$                                                                 

       SQLEXT  : packed array [1..8] of char;                              

       end;

The following elements in this record are available for you to use in status checking. The other elements are reserved for use by ALLBASE/SQL only.

   SQLCA.SQLCODE or SQLCODE

   SQLCA.SQLERRD[3]

   SQLCA.SQLWARN[0] or SQLCA.SQLWARN0

   SQLCA.SQLWARN[1] or SQLCA.SQLWARN1

   SQLCA.SQLWARN[2] or SQLCA.SQLWARN2

   SQLCA.SQLWARN[3] or SQLCA.SQLWARN3

   SQLCA.SQLWARN[6] or SQLCA.SQLWARN6

In conformance with XOPEN standards, SQLCODE can be used to address this particular element, and each SQLWARN element can be addressed without the use of square brackets. If you choose to use XOPEN standards addressing, you must include the following compiler directive in your source code:

   $ SET `XOPEN_SQLCA=TRUE'$

(Note, use this compiler directive only if you are using XOPEN standards addressing.)

The SQLCA must be passed whenever you call a subprogram that executes SQL commands. The recommended method of doing so is to declare the SQLCA globally in the main program. This is true even though your main program contains no other SQL statement. The SQLCA must be a VAR parameter to these subprograms in order to save space and attain the best performance.




	NOTE: 300/400 Series 300 and Series 400 systems do not allow subprograms.

Table 5-1 SQLCA Status Checking Fields

FIELD NAME	SET TO	CONDITION
SQLCA.SQLCODE or SQLCODE	0 Less than 0 100	No error occurred during command execution Error, command not executed No rows qualify for DML operation (does not apply to dynamic commands)
SQLCA.SQLERRD[3]	Number of rows put into output host variables Number of rows processed 0 0	Data retrieval operation Data change operation Error in single row data change operation SQLCODE equals 100
SQLCA.SQLWARN[0] or SQLCA.SQLWARN0	W	Warning, command not properly executed
SQLCA.SQLWARN[1] or SQLCA.SQLWARN1	W	At least one character string value was truncated when being stored in a host variable
SQLCA.SQLWARN[2] or SQLCA.SQLWARN2	W	At least one null value was eliminated from the argument set of an aggregrate function
SQLCA.SQLWARN[3] or SQLCA.SQLWARN3	W	For dynamic commands only, when the number of host variables in a SELECT or FETCH is unequal to the number of columns in the table being operated on
SQLCA.SQLWARN[6] or SQLCA.SQLWARN6	W	The current transaction was rolled back

SQLCODE

SQLCODE can contain one of the following values:

0, when an SQL command executes without generating a warning or error condition.
A negative number, when an SQL command cannot be executed because an error condition exists.

100, when no row qualifies for one of the following commands, but no error condition exists:

   SELECT                                 FETCH

   INSERT                                 BULK FETCH

   UPDATE (non-dynamic execution only)    UPDATE WHERE CURRENT

   DELETE (non-dynamic execution only)    DELETE WHERE CURRENT

   BULK SELECT

Note that when you prepare and execute UPDATE or DELETE commands and no rows qualify for the operation, SQLCODE is not set to 100. You can use SQLCA.SQLERRD[3] to detect this condition, as discussed later in this chapter.

Negative SQLCODE values are the same as the numbers associated with their corresponding messages in the ALLBASE/SQL message catalog. For example, the error message associated with an SQLCODE of -2613 is:


   Precision digits lost in decimal operation MULTIPLY.  (DBERR 2613)

SQLCODE is set by all SQL commands except the following directives:

   BEGIN DECLARE SECTION

   DECLARE

   END DECLARE SECTION

   INCLUDE

   WHENEVER

When SQLCODE is -4008, -14024, or a greater negative value than -14024, ALLBASE/SQL automatically rolls back the current transaction. When this condition occurs, ALLBASE/SQL also sets SQLWARN[6] to W. Refer to the discussion later in this chapter on SQLWARN[6] for more on this topic.

More than one SQLCODE is returned when more than one error occurs. For example, if you attempt to execute the following SQL command, two negative SQLCODE values result:


   EXEC SQL ADD PUBLIC, GROUP1 TO GROUP GROUP1;

The following SQLCODES associated with the two errors are:

———-2308, which indicates the reserved name PUBLIC is invalid.

———-2318, which indicates you cannot add a group to itself.

To obtain all SQLCODEs associated with the execution of an SQL command, you execute the SQLEXPLAIN command until SQLCODE is 0:

       if SQLCA.SQLCODE = 100 then

         writeln('No rows qualified for this operation.');

       else

         if SQLCA.SQLCODE < 0 then SQLStatusCheck;

       .

       .

       .

   procedure SQLStatusCheck;

   begin

     repeat

     EXEC SQL SQLEXPLAIN :SQLMessage;

     writeln(SQLMessage);

     until SQLCA.SQLCODE = 0;

   end;

The procedure named SQLStatusCheck is executed when SQLCODE is a negative number. Before executing SQLEXPLAIN for the first time, the program has access to the first SQLCODE returned. Each time SQLEXPLAIN is executed subsequently, the next SQLCODE becomes available to the program, and so on until SQLCODE equals 0.

This example explicitly tests the value of SQLCODE twice: first to determine whether it is equal to 100, then to determine whether it is <0. If the value 100 exists, no error will have occurred and the program will display the message, "No rows qualify for this operation."

It is necessary for the program to display its own message in this case because SQLEXPLAIN messages are available to your program only when SQLCODE contains a negative number or when SQLWARN[0] contains a W.

The SQLCODE is also used in implicit status checking in the following situations:

ALLBASE/SQL tests for the condition SQLCODE less than 0 when you use the SQLERROR option of the WHENEVER command.
ALLBASE/SQL tests for the condition SQLCODE equal to 100 when you use the NOT FOUND option of the WHENEVER command.

In the following situation, when ALLBASE/SQL detects a negative SQLCODE, the code routine at label 2000 is executed. When ALLBASE/SQL detects an SQLCODE of 100, the code routine at label 4000 is executed instead, as follows:

   EXEC SQL WHENEVER SQLERROR GOTO 2000;

   EXEC SQL WHENEVER NOT FOUND GOTO 4000;

WHENEVER commands remain in effect for all SQL commands that appear physically after them in the source program until another WHENEVER command for the same condition occurs.

The scope of WHENEVER commands is fully explained later in this chapter under "Implicit Status Checking Techniques."

SQLERRD[3]

SQLERRD[3] can contain one of the following values:

0, when SQLCODE is 100 or when one of the following commands causes an error condition:
INSERT UPDATE DELETE UPDATE WHERE CURRENT DELETE WHERE CURRENT
If an error occurs during execution of INSERT, UPDATE, or DELETE, one or more rows may have been processed prior to the error. In these cases, you may want to either COMMIT WORK or ROLLBACK WORK, depending on the application. For example, if all or no rows should be updated for logical data consistency, use ROLLBACK WORK. However, if logical data consistency is not an issue, COMMIT WORK may minimize re-preprocessing time.
A positive number, when SQLCODE is 0. In this case, the positive number provides information about the number of rows processed in the following data manipulation commands:
The number of rows inserted, updated, or deleted in one of the following operations:
BULK INSERT INSERT UPDATE DELETE UPDATE WHERE CURRENT DELETE WHERE CURRENT
The number of rows put into output host variables when one of the following commands is executed:
SELECT BULK SELECT FETCH BULK FETCH
A positive number when SQLCODE is less than 0. In this case, SQLERRD[3] indicates the number of rows that were successfully retrieved or inserted prior to the error condition:
BULK SELECT BULK FETCH BULK INSERT
As in the case of INSERT, UPDATE, and DELETE, mentioned above, you can use either a COMMIT WORK or ROLLBACK WORK command, as appropriate.

SQLCA.SQLWARN[0]

A W in SQLWARN[0] in conjunction with a 0 in SQLCODE indicates that the SQL command just executed caused a warning condition.

Warning conditions flag unusual but not necessarily important conditions. For example, if a program attempts to submit an SQL command that grants an already existing authority, a message such as the following would be retrieved when SQLEXPLAIN is executed:

   User peg already has DBA authorization.  (DBWARN 2006)

In the case of the following warning, the situation may or may not indicate a problem:

   A transaction in progress was aborted.  (DBWARN 2010)

This warning occurs when a program submits a RELEASE command without first terminating a transaction with a COMMIT WORK or ROLLBACK WORK. If the transaction did not perform any UPDATE, INSERT, or DELETE operations, this situation will not cause work to be lost. If the transaction did perform UPDATE, INSERT, or DELETE operations, the database changes are rolled back when the RELEASE command is processed.

You retrieve the appropriate warning message by using SQLEXPLAIN. Note that you cannot explicitly test sqlwarn[0] the way you can test SQLCODE, since sqlwarn[0] always contains W when a warning occurs.

An error and a warning condition may exist at the same time. In this event, SQLCODE is set to a negative number, and sqlwarn[0] is set to W. Messages describing all the warnings and errors can be displayed as follows:


       if SQLCA.SQLCODE <> 0 then

         repeat

         DisplayMessage;

         until SQLCA.SQLCODE = 0;

       .

       .

       .

   procedure DisplayMessage;

   begin

     EXEC SQL SQLEXPLAIN :StatusMessage;

     writeln(StatusMessage);

   end;

If multiple warnings but no errors result when ALLBASE/SQL processes a command, SQLWARN[0] is set to W and remains set until the last warning message has been retrieved by SQLEXPLAIN or another SQL command is executed. In the following example, DisplayWarning is executed when this condition exists.


   if ((SQLCA.SQLCODE = 0) and (SQLCA.SQLWARN[0] = 'W')) then

     repeat

     DisplayWarning;

     until SQLCA.SQLWARN[0] <> 'W';

     .

     .

     .

   procedure DisplayWarning;

   begin

     EXEC SQL SQLEXPLAIN :StatusMessage;

     writeln(StatusMessage);

   end;

When you use the SQLWARNING option of the WHENEVER command, ALLBASE/SQL checks for a W in SQLWARN[0]. You can use the WHENEVER command to do implicit status checking (equivalent to that done explicitly above) as follows:

   EXEC SQL WHENEVER SQLWARNING GOTO 3000;

   EXEC SQL WHENEVER SQLERROR GOTO 2000;

SQLCA.SQLWARN[1]

A W in sqlwarn[1] indicates truncation of at least one character string value when the string was stored in a host variable. Any associated indicator variable is set to the value of the string length before truncation, for example:

For example:

   EXEC SQL SELECT  PartNumber,

                    PartName

              INTO :PartNumber

                   :PartName :PartNameInd

              FROM  PurchDB.Parts

             WHERE  PartNumber = :PartNumber;

If PartName was declared as a character array of 20 bytes, and the PartName column in the PurchDB.Parts table has a length of 30 bytes, then SQL performs the following tasks:

SQLWARN[1] is set to W.
PartNameInd is set to 30 (the length of PartName in the table).
SQLCODE is set to 0.

SQLEXPLAIN retrieves the message:

             Character string truncation during storage in host variable.

             (DBWARN 2040)

SQLCA.SQLWARN[2]

A W in sqlwarn[2] indicates that at least one null value was eliminated from the argument set of an aggregrate function.

For example:

   EXEC SQL SELECT  MAX(OrderQty)

              INTO :MaxOrderQty

              FROM  PurchDB.OrderItems;

If any OrderQty values are null:

SQLWARN[2] is set to W.
SQLCODE is set to 0.

SQLEXPLAIN retrieves the message:

             NULL values eliminated from the argument of an aggregate

             function.   (DBWARN 2041)

SQLCA.SQLWARN[3]

A W in sqlwarn[3] indicates that the number of columns specified in a dynamic SELECT or FETCH statement is unequal to the number of columns indicated in the sqld field of the SQLDA. Under normal circumstances, this error does not occur, because the DESCRIBE command sets the sqld field correctly. Look at this example:

   EXEC SQL PREPARE DynamicCommand from 'SELECT PartNumber, PartName

                                           FROM PurchDB.Parts;';



   EXEC SQL DESCRIBE DynamicCommand INTO SQLDA; /*SQLDA.SQLD is always set

                                                at DESCRIBE by ALLBASE/SQL.*/

   EXEC SQL DECLARE DynamicCursor FOR DynamicCommand;

   EXEC SQL OPEN DynamicCursor;

   /* Set up the SQLDA for a fetch. */

   begin

     with SQLDA do

       begin

         SqlBufLen := sizeof(DataBuffer);

         SqlNRow := SqlBufLen DIV SqlRowLen;

         SqlRowBuf := waddress(DataBuffer);

         Sqld := 1;   /* Oops!  sqlda.sqld is incorrectly reset by the program. */

                      /* You should NEVER do this. */

                      /* Only ALLBASE/SQL should set this field. */

       end;

   end;

   .

   /* Do the fetch. */

   EXEC SQL FETCH DynamicCursor USING DESCRIPTOR SQLDA;

The FETCH will fail and ALLBASE/SQL performs the following tasks:

SQLWARN[3] is set to W.
SQLCODE is set to -2762.

SQLEXPLAIN retrieves the message:

             Select list has ! items and host variable buffer has !.

             (DBERR 2762)

SQLCA.SQLWARN[6]

When an error occurs that causes ALLBASE/SQL to roll back the current transaction, SQLWARN[6] is set to W. ALLBASE/SQL automatically rolls back transactions when SQLCODE is equal to -4008, or equal to or less than -14024.

When such errors occur, ALLBASE/SQL does the following:

Sets SQLWARN[6] to W.
Sets SQLWARN[0] to W.
Sets SQLCODE to a negative number.

If you want to terminate your program any time ALLBASE/SQL has to roll back the current transaction, you can just test sqlwarn[6].


   if SQLCA.SQLCODE < 0 then

     if SQLCA.SQLWARN[6] = 'W' then

       begin

       SQLStatusCheck;

       TerminateProgram;

       end

     else

       SQLStatusCheck;

In this example, the program executes procedure SQLStatusCheck when an error occurs. The program terminates whenever ALLBASE/SQL has rolled back a transaction, but continues if an error has occurred but was not serious enough to cause transaction roll back.

Using the SQLCA

Technical documentation

» Table of Contents

» Index

SQLCODE

SQLERRD[3]

SQLCA.SQLWARN[0]

SQLCA.SQLWARN[1]

SQLCA.SQLWARN[2]

SQLCA.SQLWARN[3]

SQLCA.SQLWARN[6]