isCOBOL Evolve : Language Reference : Embedded SQL Statements : PREPARE
PREPARE
The PREPARE statement encodes a dynamic SQL statement string and assigns it a name.
General format
EXEC SQL [ AT Database ]
 
  PREPARE { Prepared-Statement } [ INTO Sql-Descriptor ] FROM Sql-String
          { Host-Var }
 
END-EXEC
Syntax rules
1. Prepared-Statement is a Nonnumeric Literal, as defined in the Definitions section of the Preface of this document.
2. Host-Var must be USAGE HANDLE
3. Sql-String is a host variable or a Nonnumeric Literal, as defined in the Definitions section of the Preface of this document.
4. Sql-Descriptor is a IBM DB2 SQLDA implementation . This syntax is compiled only under the -csdb2 option.
General rules
1. Database identifies the active connection that will execute the query and must be previously defined using a Format 4 DECLARE statement. By default, when the AT clause is used, the active connection is switched to the connection identified by Database and all the next statements will work on that connection; under the -csora option, instead, the connection is switched only for the current statement.
2. Sql-String may contain question marks (?) that will be replaced by constant values or host variables when the statement is executed using the USING clause.
3. Host-Var should be released throgh a FREE statement before reusing it to store another prepared statement.
Examples
Prepare 2 statements, one to insert a row and one to count how many records meet a criteria
*> insert_rec and count_recs do not need to be defined prior to
*> their use in the prepare statements
*> min-key and the-count could be pic 9(4) each
 
exec sql
     prepare insert_rec from 
        "insert into cust_table values (2010,'Evan Raymond','New York')"
end-exec
 
exec sql
     execute insert_rec
end-exec
 
exec sql
     prepare count_recs from 
        "select count(*) from cust_table where cust_code > ?"
end-exec
move 1990 to min-key
exec sql
     execute count_recs using :min-key 
             into :the-count
end-exec
 
display "Count of records with key > " min-key " : " the-count