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    DB2 11 for z/OS: SQL Basic Training for Application Developers
    DB2 11 for z/OS: SQL Basic Training for Application Developers
    DB2 11 for z/OS: SQL Basic Training for Application Developers
    Ebook167 pages1 hour

    DB2 11 for z/OS: SQL Basic Training for Application Developers

    By Robert Wingate

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    About this ebook

    This book will teach you the basic information and skills you need to develop applications with DB2 SQL on IBM mainframe computers running z/OS. The instruction, examples and sample programs in this book are a fast track to becoming productive as quickly as possible using SQL with the COBOL and PLI programming languages. The content is easy to read and digest, well organized and focused on honing real job skills.

    LanguageEnglish
    PublisherRobert Wingate
    Release dateMay 29, 2019
    ISBN9781393950325
    DB2 11 for z/OS: SQL Basic Training for Application Developers
    Author

    Robert Wingate

    Robert Wingate is a computer services professional with over 30 years of IBM mainframe and distributed programming experience. He holds several IBM certifications, including IBM Certified Application Developer - DB2 11 for z/OS, and IBM Certified Database Administrator for LUW. He lives in Fort Worth, Texas.  

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      Book preview

      DB2 11 for z/OS - Robert Wingate

      Introduction

      Congratulations on your purchase of DB2 11 for z/OS: SQL Basic Training for Application Developers!  This book will teach you the basic information and skills you need to develop applications with DB2 SQL on IBM mainframe computers running z/OS. The instruction, examples and sample programs in this book are a fast track to becoming productive as quickly as possible using DB2 SQL. The content is easy to read and digest, well organized and focused on honing real job skills.

      Thanks for your purchase and if you find this SQL basic training guide useful, please leave a positive review at the place you purchased it.  I’ll really appreciate that.

      Best of luck with your DB2 career! 

      Robert Wingate

      IBM Certified Application Developer – DB2 11 for z/OS

      C:\Users\kz4hz\Documents\IBM Books\DB2 for zOS 11.0 SQL Basic Training\Kobo\DB2 11 for zOS SQL Basic Training REV1 KOBO_files\image001.jpg

      Data Manipulation Language Basics

      Overview

      Data Manipulation Language (DML) is used to add, change and delete data in a DB2 table.  DML is one of the most basic and essential skills you must have as a DB2 professional.  In this section we’ll look at the five major DML statements:  INSERT, UPDATE, DELETE, MERGE and SELECT.

      I realize that some sources do not consider the SELECT verb to be DML because it does not change the data. However I include it because it does in fact manipulate data by retrieving and displaying it. Also, you won’t get far working with SQL without knowing the SELECT statement.  So we cover it.

      Database, Tablespace and Schema Conventions

      Throughout this book we will be using a database called DBHR which is for a fictitious human relations department in a company.  The main tablespace we will use is TSHR.  Finally, our default schema will be HRSCHEMA.  In some cases we will explicitly specify the schema in our DDL or SQL.  If we don’t explicitly specify a schema, it means we have defined the HRSCHEMA schema as the CURRENT SCHEMA so we don’t need to specify it. 

      If you are following along and creating examples on your own system, you may of course use whatever database and schema is available to you on your system.  If you want the basic DDL to create the objects named above, it is as follows:

      CREATE DATABASE DBHR

      STOGROUP SGHR

      BUFFERPOOL BPHR

      INDEXBP IBPHR

      CCSID UNICODE;

      CREATE TABLESPACE TSHR

      IN DBHR

      USING STOGROUP SGHR

      PRIQTY 50

      SECQTY 20

      LOCKSIZE PAGE

      BUFFERPOOL BPHR2;

      CREATE SCHEMA HRSCHEMA

      AUTHORIZATION USER001;   This should be your DB2 id, whatever it is.

      DML SQL Statements

      Data Manipulation Language (DML) is at the core of working with relational databases. You need to be very comfortable with DML statements:  INSERT, UPDATE, DELETE, MERGE and SELECT.  We’ll cover the syntax and use of each of these.  For purposes of this section, let’s plan and create a very simple table. Here are the columns and data types for our table which we will name EMPLOYEE.

      image.jpg

      The table can be created with the following DDL:

      CREATE TABLE HRSCHEMA.EMPLOYEE(             

      EMP_ID INT NOT NULL,                 

      EMP_LAST_NAME VARCHAR(30) NOT NULL,

      EMP_FIRST_NAME VARCHAR(20) NOT NULL,

      EMP_SERVICE_YEARS INT NOT NULL WITH DEFAULT 0,           

      EMP_PROMOTION_DATE DATE,           

      PRIMARY KEY(EMP_ID)) ;              

      We also need to create a unique index to support the primary key:

      CREATE UNIQUE INDEX NDX_EMPLOYEE  

      ON EMPLOYEE (EMP_ID);       

      INSERT Statement

      The INSERT statement adds one or more rows to a table.  There are three forms of the INSERT statement and you need to know the syntax of each of these.   

      1.      Insert via Values

      2.      Insert via Select

      3.      Insert via FOR N ROWS

      Insert Via Values

      There are actually two sub-forms of the insert by values.  One form explicitly names the target columns and the other does not. Generally when inserting a record you explicitly specify the target columns, followed by a VALUES clause that includes the actual data values to apply to the new record. Let’s use our EMPLOYEE table for this example:

      INSERT INTO EMPLOYEE

      (EMP_ID,            

       EMP_LAST_NAME,     

       EMP_FIRST_NAME,    

       EMP_SERVICE_YEARS, 

       EMP_PROMOTION_DATE)

      VALUES (3217,       

      'JOHNSON',          

      'EDWARD',           

      4,                  

      '01/01/2017')       

      Note that the specified values must be ordered in the same sequence that the columns are named in the query.

      A second sub-form of the INSERT statement via values is to omit specifying the target fields and simply provide the VALUES clause.  You can do this only if your values clause includes values for ALL the columns in the correct positional order as defined in the table. 

      Here’s an example of this second sub-form of insert via values:

      INSERT INTO EMPLOYEE  

      VALUES (7459,         

      'STEWART',            

      'BETTY',              

      7,                    

      '07/31/2016')         

      Note that EMP_ID is defined as a primary key on the table. If you try inserting a row for which the primary key already exists, you will receive a -803 error SQL code. 

      Here’s an example of specifying the DEFAULT value for the EMP_SERVICE_YEARS column, and the NULL value for the EMP_PROMOTION_DATE.

      INSERT INTO EMPLOYEE 

      (EMP_ID,             

      EMP_LAST_NAME,       

      EMP_FIRST_NAME,      

      EMP_SERVICE_YEARS,   

      EMP_PROMOTION_DATE)  

      VALUES (9134,        

      'FRANKLIN',          

      'ROSEMARY',          

      DEFAULT,             

      NULL);               

      When you define a column using WITH DEFAULT, you do not necessarily have to specify the actual default value in your DDL.  DB2 provides implicit default values for most data types and if you just specify WITH DEFAULT and no specific value, the implicit default value will be used. 

      In the EMPLOYEE table we specified WITH DEFAULT 0 for the employee’s service years.  However, the implicit default value is also zero because the column is defined as INTEGER.  So we could have simply specified WITH DEFAULT and it would have the same result as specifying WITH DEFAULT 0. 

      The following table denotes the default values for the various data types. 

      image.jpg

      Before moving on to the Insert via Select option, let’s take a look at the data we have in the table

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