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<HTML
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>SQL Communication Area</TITLE
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>GNADE User's Guide: GNADE, The GNat Ada Database Environment; Version 1.2.0; Document Revision $Revision: 1.26 $</TH
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><H1
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><A
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>SQL Communication Area</A
></H1
><P
>The GNU.DB.ESQL_SUPPORT package provides a so called SQL communication
area type. This area contains informations about the result of the
last query.
<PRE
CLASS="PROGRAMLISTING"
>Syntax:
<include_sqlca_clause> ::=
INCLUDE SQLCA </PRE
>
This statement will insert a SQLCA in the Ada 95 code. If this is
done in the declare section of a procedure as shown below, the SQLCA
will be declared local to the procedure.
<DIV
CLASS="EXAMPLE"
><P
><B
>Example 11-2. Local SQLCA in procedures</B
></P
><PRE
CLASS="PROGRAMLISTING"
> procedure Print_Departement(
departement : in Integer ) is
---
EXEC SQL BEGIN DECLARE SECTION END-EXEC
Name : CHAR(1..15) := (others=>32);
.............
Salary : DOUBLE_PRECISION := 0.0;
EXEC SQL END DECLARE SECTION END-EXEC
EXEC SQL INCLUDE SQLCA ; -- Make a private SQLCA
begin
.....
EXEC SQL AT DB01
DECLARE emp_cursor CURSOR FOR
SELECT EMPNO, FIRSTNAME, NAME, JOB, MANAGER, SALARY
FROM employees
WHERE deptno = :Depno ;
....
end;</PRE
></DIV
>
The application may access the contents by using the variable
name SQLCA in the application code. This method is
preferable in a multi thread environment, because it
avoids interferences between threads through the
global variables SQLCODE and SQLSTATE.</P
><P
>The SQLCA provides several fields containing usefull information about the
most recently executed query as shown below:</P
><PRE
CLASS="PROGRAMLISTING"
> type SQLCA_Type is record
Message : aliased String(1..255 );
State : aliased SQLSTATE_TYPE;
SqlCode : aliased SQLCODE_TYPE;
Affected_Rows : aliased Integer := 0;
end record; </PRE
><P
>The parameter Affected_Rows contains the number of rows affected by
the last query.</P
><P
>State and SqlCode do contain the result code of the last
query. The SqlCode should not be used any more because the
State information contains more information.</P
><P
>The field Message contains a string generated by the underlying
dbcs containing information bout the most recent error.</P
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