Code SQL statements in RPG/400 applications

The RPG/400^® licensed program supports both RPG II and RPG III programs.

SQL statements can only be used in RPG III programs. RPG II and AutoReport are NOT supported. All referrals to RPG in this guide apply to RPG III or ILE RPG only.

This topic describes the unique application and coding requirements for embedding SQL statements in a RPG/400 program. Requirements for host variables are defined.

For more information about programming using RPG, see the RPG/400 User's Guide and RPG/400 Reference manuals on the V5R1 Supplemental Manuals Web site.

• Define the SQL communications area in RPG/400 applications that use SQL
  The SQL precompiler automatically places the SQLCA in the input specifications of the RPG/400 program prior to the first calculation specification.
• Define SQL descriptor areas in RPG/400 applications that use SQL
  There are two types of SQL descriptor areas. One is defined with the ALLOCATE DESCRIPTOR statement. The other is defined using the SQLDA structure. In this topic, only the SQLDA form is discussed.
• Embed SQL statements in RPG/400 applications that use SQL
  SQL statements coded in an RPG/400 program must be placed in the calculation section.
• Use host variables in RPG/400 applications that use SQL
  All host variables used in SQL statements must be explicitly declared. LOB, ROWID, and binary host variables are not supported in RPG/400.
• Use host structures in RPG/400 applications that use SQL
  The RPG/400 data structure name can be used as a host structure name if subfields exist in the data structure. The use of the data structure name in an SQL statement implies the list of subfield names making up the data structure.
• Use host structure arrays in RPG/400 applications that use SQL
  A host structure array is defined as an occurrence data structure. An occurrence data structure can be used on the SQL FETCH statement when fetching multiple rows.
• Use external file descriptions in RPG/400 applications that use SQL
  The SQL precompiler processes the RPG/400 source in much the same manner as the ILE RPG compiler. This means that the precompiler processes the /COPY statement for definitions of host variables.
• Determine equivalent SQL and RPG/400 data types
  The precompiler determines the base SQLTYPE and SQLLEN of host variables based on the following table. If a host variable appears with an indicator variable, the SQLTYPE is the base SQLTYPE plus one.
• Use indicator variables in RPG/400 applications that use SQL
  An indicator variable is a two-byte integer.
• Differences in RPG/400 because of structure parameter passing techniques
  The SQL RPG/400 precompiler attempts to use the structure parameter passing technique, if possible.
• Correctly end a called RPG/400 program that uses SQL
  SQL run time builds and maintains data areas (internal SQLDAs) for each SQL statement which contains host variables.