Using OpenESQL to Map COBOL to DBMS Data Types

Transcription

1 There is an easy way in Net Express to determine the correct mapping of COBOL data types to the appropriate DBMS's data types. This issue arises frequently and by using the OpenESQL assistant tool the correct data mapping can be obtained easily. This document will cover how this is accomplished. The easiest way to identify the correct COBOL data types to associate with specific DBMS's data types is to use the Host Variable Declaration feature of Net Express s Open ESQL Assistant. 1. Open a Net Express project. 2. There are options that can be specified under Options>Embedded SQL that influences what data types will be generated by the assistant. 3. These are under the section DCLGEN options. The SQL Type option is an extension provided by OpenESQL to make it easier to declare host variables that more closely reflect the type of data in a Page 1 of 10

2 SQL table. This is especially helpful for handling variable length character data, binary data and dates. It is recommended to use this option whenever possible. Page 2 of 10

3 4. From the Tools menu select OpenESQL Assistant 5. From the list of data sources, double click on the data source that points to the appropriate DBMS. Another window will appear with the data source you selected highlighted. Click OK to proceed. Page 3 of 10

4 6. You may be required to logon. Page 4 of 10

5 7. After a successful connection, a list of database tables will be displayed. Double click on the table whose database columns you want mapped to host variable data types. Page 5 of 10

6 8. Another window will appear requesting the type of query you wish to create. You can select anything, highlight the SQL verb and hit OK. Page 6 of 10

7 9. The OpenESQL assistant will now display the generated COBOL code for the SQL verb you selected. 10. The right hand window has 6 tabs, depress the Auxiliary code tab and click Host Variable Declaration. This causes a copybook to be generated in your project. The copybook name is the name of your table with a.cpy extension. In this example be the generated copybook will be named AUTHORS.CPY Page 7 of 10

8 11. The copybook will contain the following sections: 1. A DECLARE TABLE section that describes the structure of the table, the column name and associated DBMS data type. For the AUTHORS table the DECLARE TABLE was generates as the following: EXEC SQL DECLARE authors TABLE ( au_id id(11) NOT NULL,au_lname varchar(40) NOT NULL,au_fname varchar(20) NOT NULL,phone char(12) NOT NULL,address,city,state,zip varchar(40) varchar(20) char(2) char(5),contract bit(1) NOT NULL ) END-EXEC. 1. A group level item will contain all the host variables associated with each column in the table and its declared COBOL data type. This group level name will be DCL concatenated with the table name, for our example 'DCLauthors': The following was generated with SQL TYPE turned off in the Options. *> COBOL DECLARATION FOR TABLE authors 01 DCLauthors. 03 au-id PIC X(11). Page 8 of 10

9 03 au-lname PIC X(40). 03 au-fname PIC X(20). 03 phone PIC X(12). 03 address PIC X(40). 03 city PIC X(20). 03 state PIC X(2). 03 zip PIC X(5). 03 contract PIC S9(04) COMP-5. The following was generated with SQL TYPE selected in the Options. *> COBOL DECLARATION FOR TABLE authors 01 DCLauthors. 03 au-id SQL TYPE IS CHAR(11). 03 au-lname SQL TYPE IS CHAR(40). 03 au-fname SQL TYPE IS CHAR(20). 03 phone SQL TYPE IS CHAR(12). 03 address SQL TYPE IS CHAR(40). 03 city SQL TYPE IS CHAR(20). 03 state SQL TYPE IS CHAR(2). 03 zip SQL TYPE IS CHAR(5). 03 contract PIC S9(04) COMP-5. This section contains the COBOL data types that map to the corresponding DBMS's data types. Merely associate the column from the DECLARE table section with the associated host variable to determine the correct COBOL data type. Page 9 of 10

10 For example, CONTRACT is defined in SQL SERVER as a bit (as identified in #11.1 above), the correct declaration for the corresponding host variable CONTRACT is a PIC S9(04) COMP-5. This is the method used to associate a DBMS data type with the appropriate COBOL data type. 1. A group level item will contain all the NULL indicators for each column in the table. This group level name will be '-NULL' appended to 'DCL' concatenated with the table name, for our example 'DCLauthors-NULL': *> COBOL INDICATOR VARIABLES FOR TABLE 01 DCLauthors-NULL. 03 address-null PIC S9(04) COMP city-null PIC S9(04) COMP state-null PIC S9(04) COMP zip-null PIC S9(04) COMP-5. Page 10 of 10