The SQLCA helps in the communication between DB2 and COBOL-DB2 program. The SQLCA has multiple fields which gives us different information regarding the last executed SQL query.The SQLCA is mandatory in a COBOL-DB2 program. However, if we do not give the SQLCA using the INCLUDE statement then the program compilation will fail and we will get the below error in the logs−“SQLCA is not defined as a data-name”

The DATE, TIME and TIMESTAMP DB2 data types occupy 4, 3 and 10 bytes respectively. The memory occupied by the CHAR data types is occupied as per the size given. Below table shows the equivalent COBOL data types for CHAR, DATE, TIME and TIMESTAMP.DB2 data typeDB2 BytesCOBOL equivalentCOBOL bytesCHAR(z)zPIC X(z)zDATE4PIC X(10)10TIME3PIC X(8)8TIMESTAMP10PIC X(26)26

The DCLGEN utility converts the table column from DB2 data types to host variables having equivalent COBOL data types. The SMALLINT and INTEGER is converted to COBOL signed numeric data types and DECIMAL is converted to COBOL signed numeric with implied decimal. Below are the equivalent COBOL data types for SMALLINT, INTEGER and DECIMAL.DB2 data typeDB2 BytesCOBOL equivalentCOBOL bytesSMALLINT2PIC S9(4) COMP2INTEGER4PIC S9(9) COMP4DECIMAL(x,y)INT(x/2)PIC S9(x-y)V9(y)INT(((p+q)/2) +1)

The main difference between INCLUDE and COPY statement is the PDS member with INCLUDE statement is expanded during pre-compilation while the PDS member with COPY statement is expanded during compilation.Since the DCLGEN member contains column names of the table (table structure) it is necessary to expand it during the pre-compilation. This is because at the time of precompilation all the SQL statements are validated, placed in DBRM and finally replaced by appropriate COBOL calls.If the DCLGEN members are given with COPY statement instead of INCLUDE statement, then it will result in DB2 warnings during pre-compilation as the pre-compiler would not ... Read More

A COBOL-DB2 program can query/update/insert/delete data from multiple DB2 tables. However, in order to achieve this, we must fulfill two main conditions.Notify the structure of the DB2 table to the COBOL-DB2 program. This includes all the columns and data types of these columns.The respective host variables for each column. The host variables are used in the program logic to move the data from DB2 to program and vice versa. There is one host variable for every table column based on its data type. For example, for a table column with data type CHAR(2), there should be a host variable with ... Read More

We use fields of SQLCA to enquire about the status of the most recently executed SQL query. The SQLCODE is one such field which can take the various values and each value indicates specific error code. For example, -180 error code represents incorrect timestamp format. However, in the logs we only get the error code and every time we have to refer to the IBM documentation to check the description of the error code.To overcome this problem, we use DSNTIAR. The DSNTIAR is an inbuilt utility which is provided by IBM to be used in a COBOL-DB2 program.This utility displays ... Read More

A COBOL-DB2 program can have multiple DB2 SQL statements. In order to implement the common error-trapping for all the SQL statements in a COBOL-DB2 program, we will use WHENEVER statement.The WHENEVER statement can direct the control to the error handling section or routine based on the value returned in SQLCODE field of SQLCA. For example, we can declare WHENEVER statement in COBOL-DB2 program as below−EXEC SQL    WHENEVER SQLERROR GOTO ERROR-ROUTINE END-EXECIn the above example, the SQLERROR parameter will be set only when the value of SQLCODE will be lesser than zero, which indicates that there was some error occurred ... Read More

SQLCA stands for SQL-Communication Area. It is a medium through which DB2 can communicate with the COBOL program. In a typical COBOL-DB2 program, there are many SQL statements used. The main purpose of SQLCA is to inform the COBOL program about the status and other details of the most recently executed SQL query.The SQLCA has a total length of 136 bytes and it is composed of various fields like SQLCODE, SQLERRD, SQLWARN, etc. Each of these fields give specific details of the last executed SQL query.For example, SQLCODE returns the DB2 error code (if any), SQLWARN returns the warning issued ... Read More

The non-clustered index is just the opposite of the clustered index. In a non-clustered index, it is not necessary that the data rows having similar index keys should reside in the same page. This index is suitable if we have to traverse through the table.For example, if we take the scenario where index keys of the table are the whole number - 2, 12, 14, etc. Then the non-clustered index structure would look like below−

In a CLUSTERED INDEX of a DB2 table, the data rows (table rows) with the similar index keys are stored in the same page. For example, If we have 4 index keys - T5623, T5611, Z9786 and Z9078. So the data rows with similar keys T5623 and T5611 will be stored in the same page and other similar keys Z9786 and Z9078 will be stored together on the other page.The Clustered index structure has 2 types of pages i.e., Index page and data page. The index page stores all the index key values and points to the data page so ... Read More