• An alternative database interface language

• NOT a database management system

• High level, simple statement formats

• A language used for:

• Data Definition (DDL)

• Data Manipulation (DML)

• Completely interchangeable data methods

• SQL tables may be accessed with native language

• DDS created files can be access with SQL

• Great for selecting and manipulating groups of data • If you want to update/delete all the records in a file matching a certain

criteria, use SQL. SQL can change or delete a group of records in a single statement, whereas native I/O would require you to loop through a file and issue individual update or delete statements.

• Columnar functions allow for column/field manipulation during the record selection phase • SQL has many columnar functions designed to tally, total, summarize,

manipulate, and calculate columns of data. Many program features such as substringing, averaging, and math functions can be performed during the record selection phase. Columns can even be returned that don't exist in the file, such as counts, calculations, literals, and dates.

• Aggregate data • if you wanted to find a list of all the different zip codes in a mailing

address file and count how many addresses were in each zip code, SQL can easily accomplish this in a single statement. In native I/O you would have to loop through a file and increment counter fields or use arrays and/or multiple-occurrence data structures to aggregate like data.

• Interactive SQL

STRSQL

Quick ad-hoc queries

• Embedded SQL

Alternative to native file I/O

Allows for SQL functionality in RPG or COBOL

• STRSQL (Green Screen)

• System i Navigator

• Most Common SQL Statements

The SELECT statement is used to select data from a database. The result is

stored in a result table, called the result-set.

The UPDATE statement is used to update existing records in a table.

The DELETE statement is used to delete rows in a table.

• SELECT *

FROM EMPLOYEE

• SELECT EMPNO, LASTNAME, BIRTHDATE, SALARY

FROM EMPLOYEE

WHERE SALARY > 30000

• SELECT LASTNAME, SALARY, BONUS, COM

FROM EMPLOYEE

WHERE SALARY > 22000 AND BONUS = 400

OR BONUS = 500 AND COM < 1900

ORDER BY LASTNAME

• UPDATE table_name

SET column1=value, column2=value2,...

WHERE some_column=some_value

• Be careful when updating records !!!

If you omit the WHERE, all records get

updated

• Example: UPDATE EMPLOYEE

SET SALARY = SALARY + 1000

WHERE WORKDEPT = 'C01'

• DELETE FROM table_name

WHERE some_column=some_value

• BE CAREFUL WHEN DELETING RECORDS!

Like the UPDATE statement, if you omit the

WHERE clause, all records get deleted.

BACK IT UP!

• Example:

DELETE FROM TESTEMP

WHERE EMPNO = '000111'

• Static SQL

The simplest form of embedding SQL in RPG or COBOL

The SQL statement is hard coded in your program

• Dynamic SQL

The SQL statement is assembled at run-time

Requires more resource at run-time for preparing the statement

Makes an application very dynamic

Can become very sophisticated

• Most variables defined in RPG or COBOL can be used in a SQL

statement

• Variables are preceded by a colon, ( : ).

• Example:

To use RPG or COBOL’s variable field name

ITMNBR in SQL use it as :ITMNBR

COST OF ON HAND INVENTORY

ITEM# DESCRIPTION COST QTY OH COST OH

20001 Telephone, one line 15.00 10 150.00

20002 Telephone, two line 89.00 5 445.00

20003 Speaker Telephone 85.00 6 510.00

20004 Telephone Extension Cord 1.10 25 27.50

20005 Dry Erase Marker Packs 2.25 428 963.00

20006 Executive Chairs 325.00 10 3,250.00

20007 Secretarial Chairs 55.00 13 715.00

20008 Desk Calendar Pads 5.00 56 280.00

20009 Diskette Mailers .20 128 25.60

20010 Address Books 6.00 1,680 10,080.00

20011 Desk lamp, brass 20.00 3 60.00

20012 Blue pens 20.00 7 140.00

20013 Red pens 100.00 14 1,400.00

20014 Black pens 150.00 25 3,750.00

20015 Number 2 pencils 2.50 150 375.00

20016 Number 3 pencils 4.50 25 112.50

20017 Two Drawer File Cabinets 5.50 15 82.50

20018 Manilla folders 4.00 50 200.00

20019 Hanging file folders 3.00 150 450.00

20020 Metal desk 125.00 2 250.00

::::: :::::::::::::::::::: :::: ::::: ::::::

20045 Blue paper, 8 1/2 X 11 2.95 75 221.25

20046 Continuous 8,5 X 11 paper 20.00 24 480.00

20047 Yellow paper, 8 1/2 X 11 2.95 199 587.05

20048 3 hole white paper 3.35 35 117.25

20049 3 hole lined paper 3.85 10 38.50

20050 Heavy duty stapler 9.15 5 45.75

TOTAL COST OF INVENTORY ON HAND: 51,755.90

• Step 1 – calculate average Item cost

• Read all item records and calculate the ITMCOST average

• Put the average result in AVGCOST

• Step 2 – Select Item cost > Average cost

• Re-Read all item records again and compare the ITMCOST to AVGCOST

• If the ITMCOST > AVGCOST calculate the amount of ITMCOST * ITMQTYOH to ITMCOSTOH and print the record, if NOT read next records

• Print a total of ITMCOSTOH after all records have been read.

• select avg(itmcost) from item_pf

0001.00 010313

0002.00 FItpCost2 O E Printer OflInd(PrtOver) 150612

0003.00 Drecend s n 150614

0004.00 DITEMDS E DS EXTNAME(ITEM_PF:ITEM_FMT) 091212

0005.00 Drata s 5 2 150612

0006.00 020125

0007.00 /Free 020125

0008.00 150614

0009.00 Write Heading; 020125

0010.00 010313

0011.00 EXEC SQL select avg(itmcost) into :rata from item_pf; 150614

0012.00 150614

0013.00 EXEC SQL DECLARE C1 CURSOR FOR SELECT itmnbr, 150614

0014.00 itmdescr, itmcost, itmqtyoh, itmcost * itmqtyoh as 150614

0015.00 OnHand from item_pf where itmcost > :rata; 150614

0016.00 150614

0017.00 EXEC SQL OPEN C1; 091212

0018.00 150614

0019.00 EXEC SQL FETCH C1 INTO :itmnbr, :itmdescr, :itmcost, :itmqtyoh, 150614

0020.00 :itmcostoh; 150614

0021.00 150612

0022.00 DoW not recend; 150327

0023.00 If PrtOver; // Check for overflow 020128

0024.00 Write Heading; 020125

0025.00 PrtOver = *Off; 020125

0026.00 Endif; 020125

0027.00 010313

0028.00 Write Detail; // Print detail record format 150614

0029.00 150612

0030.00 EXEC SQL FETCH C1 INTO :itmnbr, :itmdescr, :itmcost, :itmqtyoh, 150614

0031.00 :itmcostoh; 150614

0032.00 // *** Check whether no more recors to be processed 150614

0033.00 150327

0034.00 recend = (SQLCODE <> 0); 150614

0035.00 150327

0036.00 Enddo; 150614

0037.00 150612

0038.00 EXEC SQL select sum(itmcost * itmqtyoh) into :totcostoh from item_pf 150614

0039.00 where itmcost > :rata; 150614

0040.00 150614

0041.00 EXEC SQL CLOSE C1; 091212

0042.00 Write Total; // Print total record format 030731

0043.00 *InLR = *On; 020125

0044.00 /End-free 020125