Any valid PL/I host variable can be used in a SQL statement. This does not mean that
all variables are valid, however. Host variables must meet certain requirements before
PP2 can accept them as usable in SQL statements. See “Host Variable Declaration” on page 197.
Any valid PL/I variable name can be used as a host variable name, including names
with embedded underscores ( _ ). Variable names must be unique within an application,
even if they are within different blocks or procedures. PP2 does not recognize the
PL/I scope concept rules and thus uses the first variable definition it encounters.
A warning is issued when the same variable name is used more than once, if it cannot
be qualified by a structure name.
If a base level variable is declared and the name is also declared in a structure,
but the referenced field is not qualified, the precompiler uses the base level variable
declaration.
With the following structure:
DCL FIELD1 CHAR(6);
DCL 01 STRUCTURE1,
02 FIELD1 CHAR(10),
02 FIELD2 CHAR(3);
EXEC SQL
SELECT FIELDA
INTO :FIELD1
FROM TABLE1
WHERE FIELDB = ’ABC’;
The precompiler uses the address and definition of FIELD1, length 6, to receive the
data. Qualify the reference to FIELD1 in the SELECT to STRUCTURE1.FIELD1 if that is
the intended field. This is the only instance where the duplicate field name is not
considered ambiguous. The order of declaration makes no difference as to the variable
used.
Host variables that are not SQL strings can represent data values only. Do not use
them to represent database, table, view, macro or column names.
Specify host variable attributes in any order that is acceptable to the PL/I compiler.
Legal PL/I abbreviations can be used for attributes in the attribute specifications.
A host variable reference in a SQL statement must be within the scope of the variable.
PP2 does not enforce this rule because no scope checking is performed. At compilation
and execution time, however, if the reference is not within the scope, unexpected
results can occur.
Begin each host variable declaration with the keyword DECLARE or DCL. Exceptions are
structure definitions where subsequent variables are a part of the structure, or in
specifying multiple variables with a single declare (that is, DCL VAR1 CHAR(6), VAR2
CHAR(3);).
The only arrays recognized by PP2 are indicator arrays.
Host variables can be AUTOMATIC, BASED, CONTROLLED or STATIC.
PICTURE clauses are not considered valid definitions for variables used in SQL statements.
Host variables having the same attributes can be declared using a list format (that
is, DCL (VAR1,VAR2,VAR3) CHAR(6) ; ).
The DEFINES clause is valid for a variable declaration only if:
The variable is an 01 level
The variable name is valid
The variable definition is valid (that is, the PIC clause)
The variable is not an array